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Recently, there has been a shift in the global healthcare paradigm, which is prioritizing a more patient-centric approach causing an increase in the demand for rapid and point-of-care (PoC) biomolecular detection. Electrochemical (EC) signal transduction has been used to great effect to meet some of this demand by constructing biosensors with high sensitivity and low limit-of-detection (LOD). However, signal generation in EC biosensors requires input bias potentials to activate electrochemical redox reactions. This means EC systems are inherently built-in with high background noise that limits the performance of biosensors. Biosensors with photoelectrochemical (PEC) signal transduction have recently shown great promise in being able to deliver biomolecular detection on par with, if not better than, EC biosensors. PEC biosensing directly improves upon EC signal transduction by combining EC signal readout with optical excitation as the bias input, and generally being able to achieve similar performance with simpler bioassay designs. In this scheme, the input and output of the signal transduction are decoupled from each other, significantly reducing background signal in biosensors to enhance their sensitivity. Despite being highly effective, PEC biosensors have yet to find commercial breakthrough as they have so far only shown quantitative analysis on a limited set of biomarkers and have not shown to be PoC-capable. In this thesis, we developed new strategies to improve PEC signal transduction so that it could be applied to build robust ultrasensitive PoC biosensors with high dynamic range, simple operation, and low LOD for detecting a wide variety of different disease biomarkers. The most popular photoactive materials used in the fabrication of PEC biosensors are TiO2 nanomaterials on account of their availability, chemical stability, high catalytic efficiency, tunable morphology, and ideal band energy levels for driving useful EC reactions. However, unmodified TiO2 suffers from several drawbacks that limit its photocurrent generation efficiency, such as poor visible range absorbance due its wide bandgap and fast charge carrier recombination. Alongside the additional difficulty of biofunctionalization, PEC biosensors fabricated from TiO2 nanomaterials are limited in their bioanalytic performance. In order to make improvements on PEC biosensors, we modified the surface of TiO2 nanomaterials by chelating them with catecholate molecules. The surface modification with catecholates formed charge transfer complexes on TiO2, which resulted in enhanced photoexcitation due to enhanced electron injection attributable to intermolecular orbital excitations in the catecholate molecules. The catecholate ligands also added improved colloidal stability and additional functional groups that aided with biofunctionalization. This resulted in multifunctional TiO2 nanoparticles with improved photocurrent signal generation and enhanced visible range photoabsorption. We took this one step further by taking advantage of the high binding affinity of catecholates on TiO2 surfaces to create novel synthesis methods that created high surface area nanostructures. Photoelectrodes fabricated from these new TiO2 nanostructures had nanoporous morphology and were able to capture biomolecules more efficiently. Using our novel TiO2 nanomaterials, we fabricated signal-off biosensors that were able to detect DNA biomarkers and IL-6 protein (cancer and inflammatory biomarker) in urine with an LOD of 1.38 pM and 3.6 pg mL-1, respectively. We further explored hybrid semiconductor structures by combining TiO2 nanomaterials with other materials such semiconductors with different bandgaps or plasmonic metal nanoparticles (NP). Using the aforementioned catechol-assisted synthesis techniques, we were able to produce different morphologies of TiO2 nanomaterials with distinct phases: anatase TiO2 nanorod assemblies and rutile TiO2 NP. The two different TiO2 nanomaterials have different bandgaps and can be used to form semiconductor heterostructures. By combining rutile TiO2 NPs with DNAzymes, a type of synthetic functional nucleic acid, we created a photoactive molecular switch that worked by making and breaking heterostructures between the two TiO2 nanomaterials. We used DNAzymes specific to E. coli bacteria to develop a highly sensitive signal-on bacterial detection platform that was able to detect E. coli in lake water samples with an LOD of 18 CFU mL-1. Using catecholate-assisted photoreduction synthesis, we developed an efficient and novel method for decorating TiO2 NP with silver (Ag) NP. The resultant nanomaterial featured TiO2 NP surfaces modified with Hematoxylin (HTX) dyes and covered with sub-nanometer sized silver NP. The band structure of TiO2/HTX/Ag NP hybrid material involved high energy electron generation through decay of surface plasmons in the Ag NP and then enhancing the photoelectron injection process between HTX and TiO2. This significantly enhances the photoexcitation and photoabsorbtion, resulting in the material with the highest photocurrent generation as presented in this thesis. By taking advantage of thiol-metal bonds, we used the TiO2/HTX/Ag NP material system in the fabrication of a highly sensitive signal-off microRNA (prostate cancer biomarker) sensor with an LOD of 172 fM in urine. Special attention was paid to the design of PEC bioassays in this work so that they are miniaturized and easy to use, and thus suitable for PoC applications. Because PEC signal transduction generates ultrahigh signals compared to other transduction methods, it allows bioassay designs to remain simple without sacrificing performance. This allowed us to create bioassays with very few operational steps, that excel in reliability and ease-of-use. To further improve PoC capability, we explored multiplexing with the biosensor made from TiO2/HTX/Ag NP. Here we were able to demonstrate multiplexing with PEC signal transduction for the first time. Another major barrier to PEC biosensors becoming widespread is the requirement of large benchtop instrumentation such as potentiostats and light sources. To address this challenge, we designed a portable smartphone-interfacing potentiostat with a built-in LED light source to support PEC biosensing. This device, named the PECsense was as versatile as any commercial potentiostats, having features such as adjustable recording periods, variable illumination periods, automatic data processing and being able to record both anodic and cathodic photocurrents. The PECsense was demonstrated to be used successfully as a signal reader in a PEC DNA detection assay. Ultimately, we designed several ultrasensitive PEC biosensors used for the detection of four different diagnostic biomarkers. Combined with the exploration of miniaturized design, multiplexing and portable signal-reading, our designed PEC biosensors were made PoC-capable. The work in this thesis presented innovations in areas of nanotechnology, material synthesis, solid-state physics, biotechnology and embedded systems for the advancement of biomolecular detection and PoC diagnostics. Thesis Doctor of Philosophy (PhD) Biosensors show great promise for use in point-of-care diagnostics and health monitoring systems. Such deceives combine biorecongition with signal transduction for analyzing biologically relevant targets. Photoelectrochemical (PEC) mode of signal reading, particularly those based on TiO2 nanomaterials, have shown great promise in delivering point-of-care biosensors that have excellent diagnostic performance. In this thesis, our goal was to develope new techniques for creating low-cost, easy-to-use and ultrasensitive photoelectrochemical biosensors. To achieve this goal, our work here can broadly be split into three objectives. Firstly, we focused on developing new material synthesis methods to improve traditional TiO2 nanomaterials so they can be more useful in PEC biosensors. These methods involved combining TiO2 with organic molecules known as catecholates and metal nanoparticles. This work created material systems that are able to generate high signals and more easily interface with biomolecules for improving PEC biosensor sensitivity. For the second objective, we used our newly developed enhanced TiO2 nanomaterials as the foundation for designing various bioassays for the detection of a wide range of different biological targets such as DNA, RNA, proteins and bacteria. This served to demonstrate the robustness of PEC signal reading as a tool for various markers of diseases. Despite PEC biosensors being a powerful tool in healthcare, they have seen very little commercial breakthrough, which can primarily be attributed to needing bulky benchtop instruments and light sources for signal reading. For the last objective, we worked on designing a handheld smartphone-operated signal-reader for PEC biosensing with its own built-in light source.

In an electrochemical sensor, the sensing performance is mainly dependent on the mass transport of the analyte towards the working electrode-electrolyte interface and working electrode properties. Carbon nanomaterials like carbon nanotubes are widely employed to modify the working electrode properties for sensitive detection. A simulation model is formulated to investigate the effects of modifying a planar bare electrode with carbon nanotubes on electrochemical detection of fenitrothion (FT, an organophosphate). The model revealed that porous electrodes caused the change in mass transport regime and influenced FT’s electrochemical response. The results aided in understanding the influence of the porous electrode on analyte detection and thus assisted in the fabrication of an ultrasensitive electrochemical sensor. Simulation supported synthesis of a highly sensitive ink to produce highly porous and electrocatalytic electrodes. Activated carbon (AC) possesses high porosity and surface area, but they suffer from lower electrical conductivity. To enhance their conductivity, AC was co-doped with nitrogen and sulfur. Multiwalled carbon nanotubes were incorporated to further improve their porosity and electrocatalytic properties. The synthesized nitrogen-sulfur co-doped activated carbon coated multiwalled carbon nanotube (NS-AC-MWCNT) ink produced highly porous electrocatalytic electrodes. The sensor revealed a 4.9 nM limit of detection (LOD) under optimized conditions. However, it failed to overcome the enzymatic sensors’ performances. The ultrasensitive performance was achieved by incorporating a detecting agent in the ink that instilled analyte capture ability. Metal oxides like ZrO2, MnO2, and MgO possessed affinity towards organophosphate (fenitrothion), heavy-metal ion (lead), and nutrient (nitrite). Metal oxides were modified with 3,4-dihydroxylbenzaldehyde (DHBA) – Chitosan (CHIT) to produce well dispersed and uniformly coated stable electrodes. The ZrO2-DHBA-CHIT/NS-AC-MWCNT sensor achieved a remarkable limit of detection of 1.69 nM for FT. The sensor's performance exceeded the enzymatic-based sensors. The commonly found chemical interferents had negligible interference. The sensor produced reliable and satisfactory performance in lake and tap water. The MnO2-DHBA-CHIT/NS-AC-MWCNT/GCE and MgO-DHBA-CHIT/NS-AC-MWCNT/GCE sensors produced an enormous improvement in the sensor performance compared to unmodified electrodes for lead and nitrite detection. The preliminary results on detecting other pollutants like lead and nitrite showed the importance of the methodology in providing a platform for a new class of metal oxide-based sensors. Thesis Doctor of Philosophy (PhD) The growing population and rapid industrial development are affecting the water quality worldwide. The major water pollutants are organophosphates, heavy metal ions, and nutrients. These water pollutants are harmful, and their bioaccumulation poses a major health concern. In the USA alone, water quality issues are predicted to cost $210 billion annually. Therefore, sensors to detect water pollutants are developed to monitor their environmental footprints. Electrochemical sensors are popularly used to detect water pollutants owing to their low-cost and high sensitivity. The objective of this dissertation was to fabricate highly sensitive and specific electrochemical sensors to detect organophosphate (e.g., fenitrothion, FT), heavy metal ion (e.g., lead), and nutrient (e.g., nitrite). The sensors were fabricated with ink based on nanomaterials like carbon nanotubes and detecting agents like metal oxides. The fabricated sensors achieved very high sensitivity and specificity and can detect water pollutants in lake and tap water.

Polymer coatings are thin films of polymer deposited on different substrates for various applications. Such surface coatings can serve a functional purpose (adhesives, photographic films), protective purpose (anticorrosion), or decorative purpose (paint). Additionally, their composite coatings containing ceramic, or metal particles are often used to enhance durability, functionality, or aesthetics. Electrophoretic deposition (EPD) and dip coating are two promising methods for the fabrication of polymer and composite coatings due to the ease of fabrication, low cost, and high-volume production. EPD involves the electrophoresis of charged particles and their deposition on the electrode surface, which requires the colloidal particles to be charged in a stable suspension as a precursor solution for deposition. Many polymers cannot be deposited by EPD directly because of their charge neutrality and poor dispersion. Therefore, it is critical to develop efficient charging dispersants to modify electrically neutral polymers for their EPD. The approach was inspired by the strong solubilization power of bile acids in the human body. Two types of bile salts, cholic acid sodium salt and sodium chenodeoxycholate, and three types of biosurfactants, carbenoxolone sodium salt, glycyrrhizic acid, and 18β-glycyrrhetinic acid, which share similar structures with bile salts, were discovered for charging, dispersion, and EPD of different materials. The electrically neutral polymers (PTFE and PVDF), chemically inert materials (diamond, nanodiamond, graphene, carbon dots, carbon nanotubes and Zr-doped hydrotalcite (MHT)), and their composites can be well dispersed in suspension and deposited using these bio-surfactants as dispersants. It was found that the unique chemical structures of these biomolecules play vital roles in the surface modification and EPD of different materials. Moreover, the deposited polymer (PVDF, PTFE) and composite (PTFE-MHT) coatings can provide outstanding corrosion protection for stainless steel. The biomimetic and versatile strategy opens a way for the deposition of other electrically neutral materials through EPD. These findings also provide a promising strategy for selecting new dispersants for EPD. The deposition of high molecular weight (MW) polymers such as poly(ethyl methacrylate) (PEMA) at high concentrations in non-toxic solvents continues to be a challenge for dip coating. In this work, we firstly proposed using water-isopropanol as a co-solvent to dissolve high MW PEMA at high concentrations. It was found that water molecules can solvate carbonyl groups of PEMA and facilitate their dissolution. This method avoided the usage of toxic solvents and a long-time heating procedure for their removal. Moreover, it allows the fabrication of high-quality PEMA and composite coatings containing different flame retardant materials (FRMs), including double hydroxide LiAl2(OH)7.2H2O (LiAlDH), huntite, halloysite and hydrotalcite, through the dip coating method. A novel solid state synthesis method was proposed to fabricate LiAlDH, which is promising for the fabrication of other advanced DHs. Such composite coatings combined advanced properties of PEMA and functional properties of FRMs, such as corrosion inhibition and FR properties. Thesis Doctor of Engineering (DEng) Polymer and composite coatings have been utilized for a wide range of applications due to their barrier properties, scratch and abrasion resistance, chemical resistance, and biocompatibility. Various techniques have been developed to fabricate polymer and composite coatings, such as electrophoretic deposition (EPD) and the dip coating method. However, limitations remain. EPD unitizes an electrical field to drive charged particles in a suspension toward conductive substrates to achieve film deposition. This process requires a stable suspension with charged particles, therefore, the electroneutral polymers present difficulties in their EPD. In addition, dissolving high molecular weight polymers at high concentrations in a non-toxic solvent is currently challenging, which is vital to utilize dip coating technique. The objective of this work was to develop advanced charging dispersants for EPD of electroneutral polymers and non-toxic solvents for dip coating of high molecular weight polymers. New biomimetic and versatile approaches have been developed for EPD of different electrically neutral polymers, chemically inert materials, and their composite coatings. A non-toxic co-solvent was proposed to dissolve high molecular weight polymer at high concentration for dip coating of the polymer and its composite coatings containing flame retardant materials. The results presented in this work showed the formation of high-quality films with multifunctionality and paved new strategies for further developments.

Supercapacitors (SCs) have generated significant interest due to their advantages including lightweight, rapid charge-discharge, good rate capability and high cyclic stability. Electrodes are one of the most important factors influencing the performance of SCs. MXene is a promising candidate for supercapacitor electrodes, which is a relatively new material with formula Mn+1XnTx, where M is a transitional metal, X stands for C or N, and Tx is surface terminations. Due to its multi-layered structure, high surface area and rich redox chemistry, good electrochemical performance can be expected. To further enhance the conductivity of the MXene electrodes, multi-walled carbon nanotubes (MCNT) were applied as the conducting additive. The as-fabricated composite electrodes showed reduced resistance and enhanced electrochemical performance. Advanced co-dispersants such as cationic celestine blue (CCB) and anionic catechol violet (ACV) were employed to improve the dispersion of components. CCB and ACV can adsorb strongly on the MXene and MCNT surface to form a homogenous suspension and thus improve the mixing between them. Another advanced dispersant 3,4,5-trihydroxybenzamide (THB) also showed adsorption on both MXene and MCNT particles, favored their dispersive mixing and improved electrochemical performance. Iron oxides are promising materials for negative electrodes for supercapacitors. The attempt to combine highly capacitive Fe3O4 with MXene-MCNT composites proved the synergistic effect of individual components. Investigation of Zn-doped FeOOH as high active mass loading anode with MCNT as conducting additive allowed for enhanced performance. Zn-Fe double hydroxide materials are promising for the fabrication of advanced supercapacitor electrodes. A safe and neutral Na2SO4 electrolyte was was beneficial for the development of asymmetric devices with enlarged voltage window. For cathodes working in an overlapping window with Zn-FeOOH anode, polypyrrole coated carbon nanotube electrode was fabricated with a comparable capacitance. The advanced dopant eriochrome cyanine R (ECR) allowed for the uniform thickness of PPy coating on MCNT and enhanced charge transfer between PPy and MCNT was achieved. Enhanced capacitive properties of cathodes and anodes at high active mass loading working in complimentary voltage windows allowed for fabrication of high-performance supercapacitor, which was a promising device for practical applications. Thesis Doctor of Philosophy (PhD) To reduce the consumption of fossil fuel and meet the surging demand of electric energy, intensive attention has been drawn to new energy storage device, such as capacitors, batteries and supercapacitors. Owing to their higher energy density compared with conventional capacitors and higher power density compared with batteries, supercapacitors are attracting tremendous research interest. The advantages of supercapacitors are fast charge-discharge rate, high power and energy density and excellent cyclic stability. The objective of this work was to fabricate high-performance supercapacitor devices based on the development of advanced electrode materials. MXene and Fe-based composite materials were synthesized by conceptually new colloidal approach and some efficient dispersants were developed during the process. The enlarged voltage window and superior performance were recorded for asymmetric supercapacitors. The results presented in this work showed much more promising performance compared with that reported in the literature and paved the way for future research.

The global market for fluoropolymers, including polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), is growing rapidly due to their copious applications in the construction, automotive, medical, chemical, and electrical industries. Fluoropolymers owe their popularity partly to their excellent chemical and thermal stability and useful mechanical, piezoelectric, and ferroelectric properties. They are made into films or coatings that are used for corrosion protection or surface property enhancement. Electrophoretic deposition (EPD) has generated increasing interest in manufacturing advanced films for various applications due to its low cost, versatility, simple apparatus, and good film quality compared with other deposition techniques like dip coating, spin coating, electrospinning, or spay coating. Moreover, EPD facilitates uniform deposition on the substrates of complex shapes at a high deposition rate. The aim of this research is to develop novel biomimetic strategies for fabricating polymer films and their composite films with multifunctional particles through EPD. This method involves the electrophoresis of charged particles in a stable colloidal suspension towards an electrode, forming deposition. Fluoropolymers, however, are electrically neutral and chemically inert, and their EPD presents difficulties. Therefore, successful EPD depends on understanding how to modify the surface of polymer particles using advanced biosurfactants to impart charge and form a well dispersed, stable colloidal suspension. One strategy is to leverage the unique dispersing power of bile acids and salts as biosurfactants for EPD of PTFE and PVDF films and composite films. When doing so, it was found that the amphiphilic structure of bile salts such as sodium deoxycholate (DChNa) facilitated adsorption on the chemically inert, hydrophobic surfaces of PTFE, diamond, and carbon dots. In this strategy, DChNa acted as a charging, dispersing, film-forming agent for the co-deposition of PTFE composite films from an aqueous suspension. Water insoluble bile acids (BAs) were found to be biosurfactants for the EPD of PTFE and PVDF from organic solvents, in which lithocholic acid (LCA) was used as a co-dispersant for the fabrication of composite PTFE-diamond coatings and PTFE coatings provided corrosion protection for stainless steel in 3% NaCl solutions. The dispersing performance of four other bile acids, chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and cholic acid (ChA), was analyzed and compared with LCA on the deposition performance of PVDF. It was found that the PVDF deposition yield obtained using different BAs increased in the order of LCA

Surface modifications of bone-interfacing biomedical devices can increase their longevity by promoting bond formation and new bone growth, while reducing the toxic effects of corrosion and wear particles. Coatings which contain biocompatible polymers, bioceramics, drugs, and functional molecules are one route to achieve this. Here, a biomimetic approach is developed for the fabrication of poly(ethyl methacrylate) (PEMA) coatings. For the first time it is shown that PEMA can be solubilized in non-toxic solvents by naturally occurring bile acids. Their unique chemical structure and amphiphilicity allows for efficient solubilization of polymer macromolecules. Advancements in colloidal sciences enable a facile deposition method termed “dip coating” to be utilized. The feasibility of highly concentrated solutions of high molecular mass PEMA was a key factor for film deposition by dip coating. Singular layers or multilayered PEMA films could be deposited. Heat-treated PEMA films provided corrosion protection to stainless steels. This inexpensive and simple technique can be up scaled to larger manufacturing levels, leading to mass production and clinical development of novel coatings for biomedical applications. Additional challenges in the fabrication of composite coatings by dip coating were successfully addressed using bile acids. To produce high quality composite coatings by dip coating, a stable suspension is required. Particle aggregation leads to uneven coatings, poor adhesion, and weakened mechanical properties. It was shown that bile acids could act as dispersing agents to mediate this. PEMA coatings containing inorganic materials hydroxyapatite, silica, titania, and diamond were fabricated. The inorganic component of the films could be increased to 50 wt.%. Model drugs tetracycline and ibuprofen were used for the creation of drug-loaded PEMA coatings. Lastly, composite coatings containing functional molecules including heparin and nanocellulose were created. Overall, these coatings provide corrosion resistance to metallic orthopedic implants, while enhancing potential biocompatibility of the device. The biomimetic approach developed in this investigation was motivated by the role of bile acids and bile salts as solubilizers of cholesterol and other molecules within the digestive system of mammals. A solubilization mechanism has been proposed. This work paves the way for the fabrication of future composite coatings containing other high molecular mass polymers, inorganic nanomaterials, and functional materials or drugs. Thesis Master of Applied Science (MASc) Biomedical devices have various properties they must possess to perform their function within the body without harming the patient. Coatings applied to these devices can mitigate the body’s response by reducing corrosion, preventing wear, and promoting bond formation. This increases the lifespan of the device and prevents invasive revision surgeries. Advances in materials engineering and colloidal sciences can help achieve these goals. Materials selection for novel coatings can be inspired by the composition of real bone - consisting of a polymer matrix with embedded inorganic nanomaterials. Additionally, manufacturing techniques that avoid high temperatures are desirable. Therefore, advances in colloidal sciences which enable coatings to be fabricated by a simple and inexpensive method known as dip coating is of paramount importance. This work used natural biosurfactants bile acids to aid in fabrication of coatings for biomedical devices using advanced polymer poly(ethyl methacrylate) and functional inorganic materials.

Electrochemical supercapacitors (ESs) are one of the most modern energy storage systems that offer a balance between power and energy densities in which the energy storage mechanisms could be an electrostatic double layer (EDLCs) and pseudocapacitive. In this thesis, hybrid asymmetric supercapacitors have been developed to optimize the advantages for different types of (ESs) such as high conductivity, stability, fast charge-discharge, and relatively high performance. These developments include high active mass loading electrodes based on multiwall carbon nanotubes (MWCNTs) and transition metal oxides with incubation of low binder percentage and a high mass loading of 40 mg cm-2 that guarantees high electrochemical performance at a wide potential range for different electrodes, especially the cathodic one. Novel synthesis techniques and different multi-dispersants have been demonstrated; a conception colloidal fabrication method has been developed to improve the morphology/dispersion for composites of Fe3O4/MWCNTs (M-CNTs) and NiFe2O4/MWCNTs. Firstly, an advanced synthesis method called particle extraction through a liquid-liquid interface (PELLI) has been developed to enhance the dispersion of the nanoparticles M-CNTs. Furthermore, palmitic acid (PA) has been used as a surfactant in the bottom-up (PELLI) to reduce the agglomeration of M-CNTs with high Gamma (𝛾𝛾) ratio (nanoparticles/MWCNTs). Moreover, different synthesis methods have been developed in the presence of celestine blue dye (CB) as a co-dispersant with advanced electrostatic interaction and coagulation mechanism that ensured well- dispersed of (Fe3O4, NiFe2O4) coated (MWCNTs) at high mass loading. Subsequently, more optimizations have been done to analyze the effect of different adsorption mechanisms by using other co-dispersant agents such as pyrocatechol violet (PV), azure A chloride (AA), and m-cresol purple (CP). Finally, cyclic voltammetry, galvanic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic stability have been done for the fabricated electrodes and devices in neutral aqueous electrolytes that showed a relevant electrochemical performance in a large potential range. Thesis Doctor of Philosophy (PhD) The rapid increase in human population has caused many economic problems, one of them the enormous energy consumption rate as compared to the limitations of sources available for clean and renewable energy sources. Energy storage systems can be classified into different types, e.g., chemical, electrochemical, thermal, and mechanical systems. Popular electrochemical energy storage systems, such as batteries and capacitors, are used for many important daily applications but have difficulties while optimizing power and energy densities. Here, electrochemical supercapacitors (ESs) are considered potential energy storage systems that could balance power and energy densities with fast charge-discharge and a long lifetime. The purpose of this research is to advance nanocomposite materials for electrochemical supercapacitor applications, where we use new colloidal approaches to fabricate high-performance electrochemical supercapacitor electrodes and devices. Our results reveal that these devices can have exceptional performance that facilitates new routes for their development.

Supercapacitor electrodes were fabricated at a high active mass loading and exhibited enhanced electrochemical capacitance. A conceptually new salting-out extraction processing technique for the synthesis of dispersed Mn3O4-carbon nanotube (CNT) nanocomposites was developed, alleviating the need for hydrophobic solvents. The choice of isopropyl alcohol and NaCl for the extraction process offer advantages of an easy upscaling of this process. The salting out technique was shown to work with Octanohydroxyamic acid (OHA) and Lauryl Gallate (LG) as extractors and dispersants, critical to the success of the extraction. Mechanisms for surface adsorption on Mn3O4 and CNT for both OHA and LG are discussed. A secondary project was also undertaken, to investigate the use of chlorogenic acid and 3,4,5 – trihydroxybenzamide, as co-dispersing agents for MnO2 and CNTs. These molecules are used due to their unique structural properties, which are discussed. The electrodes fabricated using these co-dispersants showed significant increases in their specific capacitances and SEM imaging indicated improved mixing, compared to samples prepared without dispersants. A specific capacitance of 6.5 F g-1 was achieve at low electrical resistance, attributed to the microstructure of electrodes prepared with the co-dispersant molecules. Thesis Master of Applied Science (MASc) The ever-growing realization that our energy consumption as a civilization is not sustainable, has fueled people around the globe to imagine and design new methods of energy storage, in attempts to mitigate this issue. From the foundational works of scientists, it has become clear to see that there is not “one right answer”. Instead, the unique benefits and drawbacks of energy storage technologies should be balanced and applied in situations where their properties permit a high efficacy. The intention of this work is to assist in the development of new materials to be used for energy storage devices called electrochemical supercapacitors. Novel colloidal processing techniques were developed, leading to the fabrication of high-performance electrodes, and providing further insight to the structure-properties relationship of organic extractors and co-dispersing agents for the design of nanocomposites.

In a world that relies heavily on electricity and portable energy, the development of high performing energy storage devices is crucial. The ongoing push for energy storage devices such as batteries and supercapacitors to store more energy and charge/discharge faster has become exponentially stronger over the past decade. In order to meet the high demands, new materials and processing techniques must be developed. A particle extraction through the liquid-liquid interface (PELLI) technique was used with a versatile extracting molecule, Octyl Gallate (OG). It was found that OG was able to extract a variety of materials including oxides, oxyhydroxides, and pure silver. The advantage of PELLI is that it circumvents the drying stage that occurs in many electrode synthesis techniques where metal oxides are synthesized in aqueous then dried and mixed with conductive additives dispersed in organic solvent. This drying stage causes a practically irreversible agglomeration which hinders mixing with conductive additives as well as reduces the surface area of the material, limiting its electrochemical performance. Using hydroxamates such as octanohydroxamic acid and bufexamac, a novel PELLI technique was developed based on the use of OHA as an extracting agent as well as a capping agent. In addition, a preliminary investigation was started on advanced negative electrode material for supercapacitors. FeOOH-based electrodes exhibit high capacitance but low cyclic stability. Zn2+ ions were introduced during synthesis forming a doped Zn/FeOOH electrode which showed a significant increase in cyclic stability. Thesis Master of Applied Science (MASc)

In this thesis, an advanced colloidal fabrication technique, called particle extraction through liquid-liquid interface (PELLI), has been developed to fabricate components of positive and negative electrodes of electrochemical capacitors (ECs). This new colloidal strategy is applied to create stable suspensions for the electrophoretic deposition (EPD) of thin films and advanced inks for screen printing applications. Bottom-up and top-down PELLI strategies were developed to extract MnO2 particles synthesized in an aqueous phase to the organic phases of 1-butanol and dichloromethane, respectively. During both extraction processes, hexadecylamine with amine functional group was used as the extractor for transferring the MnO2 particles. Compared to the top-down PELLI technique, the bottom-up PELLI synthesized particles of relatively small sizes, which is beneficial for fabricating MnO2-multiwalled carbon nanotube (MWCNT) binary composite EC electrodes with enhanced electrochemical performance. Hence, the subsequent work was carried out using the bottom-up strategy for PELLI. Head-tail extractors with a single functional group, such as carboxylic acid and phosphonate, and head-tail-head (HTH) multifunctional extractors with functional groups of both carboxylic acid and phosphonate were used as the vehicles for transferring MnO2 from the synthesis media to the device processing media to achieve a good suspension of MnO2-MWCNT to fabricate positive EC electrodes. Advanced FeOOH-MWCNT negative electrodes were also prepared by PELLI strategies using HT and HTH extractors. The experimental results showed that both positive and negative electrodes prepared by HTH extractors exhibit the highest electrochemical performance. Moreover, stable suspensions of MnO2 particles synthesized by PELLI with multifunctional HTH extractors were prepared to fabricate advanced thin films by EPD and also MnO2-carbon black printing inks for screen printing of thin EC electrodes. Subsequently, to fabricate efficient polypyrrole (PPy) based composite negative electrodes, for the first time, non-agglomerated FeOOH particles were prepared with PELLI using tetradecylamine as extractor. Introduction of PPy enhances the electrochemical performance of the binary composite of PPy coated MWCNT in a potential range of -0.8 - +0.1V. Advanced asymmetric ECs devices with MnO2-MWCNT positive electrodes and PPy-FeOOH-MWCNT negative electrodes were fabricated. These devices with comparable capacitance for both the positive and negative electrodes and high active mass loading were found to have high electrochemical performance in a wide working voltage window of 1.6V in aqueous electrolyte. Thesis Doctor of Engineering (DEng)

An investigation of electrochemical storage device materials has been undertaken in four parts. The bulk and interfacial resistance of Na+ beta-alumina tubes were separated using a galvanostatic charge-discharge method. Sodium silicide was characterized to better understand its synthesis. BiMn2O5 was produced using a sol-gel method and tested for pseudocapacity. Different lithium ion anode and cathode materials were deposited using a new electrophoretic deposition method. A novel galvanostatic charge-discharge method was developed for the determination of bulk and interface resistance in Na+ beta-alumina solid electrolytes [BASE]. Dense and duplex BASE tubes were tested by varying the exposed surface area. The results of dense BASE tube pairs were used to determine the bulk and interfacial resistance components, while duplex BASE tubes were tested to determine the reduction in interfacial resistance. It was found that duplex tubes had reduced the interfacial resistance by 75%, when compared to a uniformly dense electrolyte. Sodium silicide was characterized using various methods to better understand the phase and the Na-Si phase diagram. EMF experiments using Na+ BASE tubes was used to determine the activity in the silicon rich region of the phase diagram, which showed a sodium activity of 0.5 at 550°C. TGA/DSC was used to determine phase transformation temperatures, as well as the heat of formation for NaSi, which was recorded to be below 1 kJ mol-1. A sol-gel precipitation method was used to produce fine BiMn2O5 powders used for supercapacitors. The powders resulting from a consistent method were tested for pseudocapacitance using bulk and thin film electrodes. Bulk electrodes had a gravimetric capacitance of 10 F g-1, while thin film electrodes only reached 2.6 F g-1. Lithium ion battery anode (Li4Ti5O12) and cathode (LiFePO4, LiMn2O4, LiMn1.5Ni0.5O4) materials were electrophoretically deposited with the assistance of PAZO-Na and CMC-Na. Cathodes were successfully deposited on aluminium substrates, and were tested in the potential window 2 – 4.3 V. The LiFePO4 cathodes showed capacity of 146.7 mAh g-1 at C/10, while showing capacity retention of 103% after 50 cycles. Thesis Doctor of Philosophy (PhD) The goal of this work is to examine materials used in different types of electrochemical storage devices. The modification of resistive properties of β-alumina electrolytes are examined for use in high temperature sodium batteries. Electrophoretic deposition methods are used to rapidly make thin electrodes for lithium ion batteries and supercapacitors. The stoichiometric compound NaSi, a potentially safer and greener method of producing hydrogen gas, is characterized for a better understanding of its properties, and therefore production.

New electrochemical deposition methods for the preparation of organic-inorganic nanocomposite coatings were proposed. These methods are starts from the electrophoretic deposition (EPD) of ceramic nanoparticles and polymers. EPD is the motion that charged particles move towards the electrode in the applied electric field. Short processing time and process simplicity are the advantages of electrochemical deposition methods. Moreover, EPD methods for the fabrication of organic-inorganic of nanocomposites like ZnO films achieved non-agglomeration which is a promising method for the future industrial application. Electrode deposition was achieved by using 16-phosphonohexadecanoic acid (16PHA), octadecylphosphonic acid (ODPA), stearic acid (SA) and polyethylenimine (PEI) is used for dispersion. The characterization can be performed by XRD, SEM, Cyclic voltammetry, impedance spectroscopy, potentiodynamic studies, FTIR, TGA, DTA etc. For those organic-inorganic nanocomposites coatings, these various coatings are widely used in a great many aspects such as biomaterials, solar energy, aerospace, fuel cells, supercapacitors, and quantum dots. These materials, combine the properties of organic and inorganic components and exhibit advanced properties, which broaden application areas and improve the applications’ properties dramatically. The article is trying to illustrate the new electrochemical deposition methods for the fabrication of organic-inorganic nanocomposites and its principle. Thesis Master of Applied Science (MASc)

MnO2 continues to gain traction in the research and development of advanced supercapacitor materials due to its arsenal of advantages, such as high capacitance, low cost, natural abundance, and environmental benignity. However, its low conductivity has hindered its adoption into real-life applications. Compositing MnO2 with conductive additives has proved to be a promising route for the improvement of its power-energy characteristics. Four novel colloidal techniques were developed for the synthesis of MnO2-CNT composites with enhanced performance at high active mass loading. One strategy utilized a Schiff-based linkage of dispersants such as 3,4-Dihydroxybenzaldehyde (DHB) and Toluidine Blue O (TDB) to effectively mix and disperse MnO2 and CNT. Secondly, a co-dispersion technique was also investigated using Gallocyanine to improve dispersion and mixing of MnO2 and MWCNT. Third, a novel liquid-liquid extraction technique opened new avenues in agglomerate-free processing of individual components, which allowed enhanced electrode performance. Lastly, a morphology-modification strategy was also undertaken by synthesizing MnO2 nanorods with the use of advanced organic dispersants to control the aspect ratio and composite nanorods with MWCNT. The second major material investigated was polypyrrole (PPy), a polymer material with high conductivity, ease of synthesis, low-cost, and non-toxicity. However, its low cyclic stability was prevented it from being applied for real-world applications. Certain anionic and aromatic dopants have shown to improve the conductivity and cyclic stability. Therefore, one of the investigations in this work attempted to improve the performance of PPy-CNT composites by use of a novel anionic dopant, Sunset Yellow (SY). For all investigations electrodes with high mass loadings were produced to achieve high areal capacitance, thus ensuring the practicality of the techniques Thesis Master of Applied Science (MASc) Supercapacitors (SCs) and batteries are both electrochemical energy storage devices. While batteries excel at storing energy in high volumes, supercapacitors excel in charging (and discharging) at extremely high rates. It is desirable to obtain the best of both worlds in a single device; high energy volume and fast charging speeds. Although such a feat is not out of the realm of theoretical possibility, current projections forecast supercapacitors to compliment battery technologies instead of replacing them. Nonetheless, constant progression in the field of SCs is needed to sustain and proliferate their adoption into emerging markets. Therefore, the aim of this research was to assist in the endeavours to improve current SC technologies from a materials science standpoint.

Electrochemical supercapacitors (ESs) are currently under development for electronics and automotive applications due to their hybrid properties inherited from batteries and capacitors. ESs exhibit higher power densities than batteries and energy densities than capacitors, and offer long cyclic life and rapid charge-discharge suitable for many applications. A promising candidate of electrode materials is manganese dioxide (MnO2), which has the advantages of high theoretical capacitance, low cost and environmentally friendly. However, the low electronic and ionic conductivities of MnO2 have limited its performance for practical applications. It has been demonstrated in literature that composite materials, which consist of conductive additives such as multi-walled carbon nanotubes (MWCNTs) and MnO2 can address this problem, however further investigations are required to produce ESs with superior performance for real-world applications. In this dissertation, novel colloidal fabrication techniques have been developed and advanced dispersants were employed to fabricate advanced nanocomposite electrodes. MnO2-MWCNTs composite electrode was fabricated with use of multifunctional dispersant. The multifunctional dispersant cetylpyridinium chloride (CPC) showed good dispersion of MWCNTs and capability of forming complex with the precursor of MnO2, which improved the homogeneity of the composite and generated unique morphology. The MnO2-MWCNTs composite electrode fabricated exhibited remarkable areal capacitance at high active mass loadings. New scalable fabrication technique was developed for MnO2-MWCNTs by using high solubility sodium permanganate (NaMnO4) precursor. The fabricated composite electrode showed superior performance compared to electrodes fabricated by other colloidal techniques at similar mass loading. Liquid-liquid extraction was employed to address the problem of particles agglomeration upon drying. Bio-inspired advanced extractor lauryl gallate (LG) was used for liquid-liquid extraction of particles. LG has organic catechol group allowed for strong adsorption on inorganic particles. Using LG as an advanced extractor has facilitated the transfer of particles from aqueous to organic phase to prevent agglomeration associated with drying procedure and improved mixing with MWCNTs. Advanced dispersants from bile acid salts and charged aromatic dyes families such as sodium taurodeoxychloate (TDS) and tolonium chloride (TL) were used as MWCNTs dispersants, to fabricate composite electrode with alternative metal oxides such as Mn3O4 and V2O3. Furthermore, 3,4-dihydroxybenzaldhyde (DHB) was investigated as a dispersing agent for Mn3O4 and used to fabricate Mn3O4-MWCNTs composite electrode with TL by Schiff base formation. Mn3O4 offers the advantages of small particle size compared to MnO2, and can be converted to MnO2 by electrochemical cycling to enhance capacitive performance. V2O3 was considered as an alternative to MnO2 due to its metallic conductivity at room temperature. An activation procedure has been developed, which promoted the formation of capacitive V2O5 surface layer on conductive V2O3 to increase capacitance. The advanced dispersants have shown excellent dispersion of MWCNTs in aqueous solutions at low concentrations and facilitated the formation of homogeneous composite with Mn3O4 and V2O3. Activation procedures were developed for the Mn3O4 and V2O3 composite electrodes, and the electrodes with high active mass loadings showed exceptional performance after activation. Thesis Doctor of Philosophy (PhD) In modern society, the demand for clean and renewable energy have grown drastically and there is a need in development of advanced energy storage devices. Currently, the most common energy storage devices are batteries or conventional capacitors. Batteries can store a large amount of energy, however they are limited by their low power performance. Capacitors can charge and discharge rapidly, but the amount of energy stored is relatively low. Other than batteries and capacitor, electrochemical supercapacitors are emerging energy storage devices that offer the advantages of high power and energy density, fast charge-discharge and long lifetime. The objective of this work was to develop advanced nanocomposite electrode materials for electrochemical supercapacitor applications. New colloidal processing strategies have been developed and advanced dispersants were employed for the fabrication of high performance nanocomposites for electrochemical supercapacitor applications. The results presented in this work showed exceptional performances compared to literature data and paved a new way for further developments.

Development of a new generation of nanocomposite biomedical implant coatings that contain bioactive ceramics and polymers and tailored surface features, both of which promote cell adhesion, proliferation, and interlocking at the bone tissue/implant interface, is crucial to extending the lifespan of orthopaedic implants. Use of combined colloidal and electrochemical processing techniques, in particular electrophoretic deposition (EPD), have the ability to fabricate these new multi-component materials with relative ease. They also can be used to fabricate nanostructures and surface topography, that mimic the structure of human skeletal tissue at the nanoscale. Furthermore, colloidal-electrochemical processing techniques may also be easily upscaled, towards clinical product development and mass manufacturing, unlike many processing techniques commonly used in nanotechnology. Since the success of EPD depends on the use of a stable colloidal precursor, barriers to widespread use of colloidal-electrochemical methods for fabrication of these novel biomaterials, is the lack of efficient and biocompatible dispersants and extractors. One approach to developing suitable dispersing and extracting agents lies in deriving inspiration from the natural world, also known as biomimetics. Based on this approach, new extracting agents inspired by the chemical structure of mussel adhesive proteins (MAPs) were discovered for the efficient particle extraction and formation of organic-inorganic composite films, containing hydroxyapatite (HA) nanorods. Building upon this approach, we utilized catechol (CAT), the functional group in MAPs that allows for their ultra-strong adhesion, and functionalized amine-containing biopolymers. We used chitosan (CHIT) and poly-L-lysine (PLL) as model biopolymers and found that CAT functionalization imparted remarkable properties such as robust adhesion, stability across a wider pH range, and redox-capacitance. Future applications of these films were explored, including not only orthopaedic implant applications, but also electrochemical and photoelectrochemical sensing applications. Finally, biomimetic inspiration was derived from the human digestive system, to use bile acid salts (BAS) as powerful solubilizing, charging, dispersing and film-forming agents for the fabrication of composite coatings, containing water insoluble drugs. These coatings can be used for local drug delivery of anti-biotics, to prevent surgical infection post-implantation, and use of BAS surfactants paves the way for solubilization and dispersion of other hydrophobic functional drugs and molecules, as well as fabrication of functional composite films using EPD. Thesis Doctor of Engineering (DEng)

With many processing advantages, electrophoretic deposition (EPD) has been chosen as the fabrication technique for inorganic-organic nanocomposites. However, before the EPD process, avoiding the particles agglomeration is considered a necessary perquisite for the success of fabrication. In this research, two different liquid-liquid extraction methods, one is one-step and the other is two-step, were developed to solve the agglomeration problem of inorganic particles. The adsorption mechanisms of the extractors and extraction mechanisms were investigated during this work. The strong adsorptions provided by –OH groups of the extractors and further Schiff base reaction allowed for the process of extraction. In the fabrication, polyelectrolytes acted as the film forming and charging agents. Relatively stable suspensions with extracted inorganic particles were prepared for the EPD of inorganic-organic nanocomposites. The thickness of deposited films is proportional to the concentration of the suspension and deposition time. With the addition of flame retardant inorganic particles, the prepared nanocomposite films showed an enhanced flame retardant performance. Thesis Master of Applied Science (MASc)

The growing interest in the application of polypyrrole (PPy) for electrodes of electrochemical supercapacitors (ES) is attributed to the relatively high specific capacitance (SC), low cost, high electrical conductivity, advanced chemical and mechanical properties of PPy. However, it is found that swelling and shrinkage occurred during charge-discharge, resulting in higher impedance, gradual adhesion loss and poor cycling behavior of PPy electrode. Moreover, mass normalized capacitance decreased significantly with increasing electrode mass, especially at high charge-discharge rates. Therefore, it is challenging to achieve good electrochemical performance, cyclic stability and good capacitance retention at high charge-discharge rates for electrodes with mass loadings above 20 mg/cm2, which is required for many practical applications.To address this problem, PPy-MWCNT (multiwalled carbon nanotube) composites were prepared using polycharged aromatic anionic redox active molecules as dopants for PPy and dispersants for MWCNT. New dopants offer the advantages of their reduced movement during charge-discharge process and reduced PPy swelling because of large molecular size. In addition, polycharged dopants, containing several charged groups, can be linked to different polymer macromolecules, thus increasing interchain mobility of charge carriers and increasing PPy conductivity. Moreover, new dopants exhibit redox active properties and thus contribute to the total electrode capacitance. The reasons for adding MWCNTs are following: first, they can enhance charge storage properties of PPy by increasing the conductivity of composites, which is more obvious when the scan rate is high. Second, the network formed by MWCNTs can restrict the swelling of PPy and improve the cyclic stability.In this research, new promising PPy-MWCNT electrodes were fabricated. 7 different molecules were used as new dopants for chemical synthesis of PPy. The molecular size and functional groups of the anionic dopants and dispersants have great influence on the morphology and capacitive properties of PPy and PPy/MWCNT composites. Moreover, PPy-MWCNT-FeOOH composite was also prepared in order to shift the working voltage window of PPy/CNT composite to more negative direction, which can facilitate the utilization of PPy as negative electrode. The results showed that dopants with large size, multiple charges and high charge to mass ratio can decrease PPy particle size, reduce agglomeration and thus improve PPy capacitive properties. The highest SC of 118.26 F/g was achieved at 2 mV/s by using PMSS-SR31 doped PPy-MWCNT electrodes. The highest SC of 65.09 F/g at 100 mV/s was achieved by using Potassium Benzene-1,2-disofulnate doped PPy-MWCNT electrodes. Adding FeOOH to PPy-MWCNT composite with mass ration between PPy and FeOOH of 7/2 allowed for enhanced performance in a working voltage window of -0.8 - +0.1 V, which facilitated the utilization of PPy as a negative electrode in asymmetrical device. Thesis Master of Applied Science (MASc)

Electrochemical supercapacitors (ESs) have attracted great attention due to the advantages of long cycle life, high charge/discharge rate and high power density compared to batteries. Significant improvement in ES performance has been achieved via development of advanced nanostructured materials, such as MnO2 and composite MnO2-MWCNT and PPy-MWCNT electrodes. In this dissertation, advanced dispersants were developed and investigated for the dispersion, surface modification and electrophoretic deposition (EPD) of metal oxides, multiwalled carbon nanotubes (MWCNT) and polypyrrole (PPy) in different solvents. Nature-inspired strategies have been developed for the fabrication of MWCNT films and composites. The outstanding colloidal stability of MWCNT, dispersed using anionic bile acids, allowed the EPD of MWCNT. Composite MnO2-MWCNT films were obtained by anodic EPD on Ni plaque and Ni foam substrates. Good dispersion of MWCNT during Py polymerization was achieved and allowed the formation of PPy coated MWCNT. The film and bulk electrodes, prepared by EPD and slurry impregnation methods, respectively, showed high capacitance and good capacitance retention at high charge-discharge rates. The mechanisms of dispersion and deposition were investigated. Cathodic and anodic EPD of MWCNT, MnO2, Mn3O4 was achieved using positively and negatively charged dispersants. Co-deposition of MWCNT and MnO2 was performed using a co-dispersant, which dispersed both MWCNT and MnO2 in ethanol. Composite films were tested for ES applications. The efficient dispersion was achieved at relatively low dispersant concentrations due to strong adsorption of the dispersants on the particle surface, which involved the polydentate bonding. We found the possibility of efficient dispersion of MWCNT in ethanol using efficient anionic dispersants. The electrostatic assembly method has been developed, which offers the benefit of improved mixing of MnO2 and MWCNT. The use of different anionic and cationic dispersants allowed the fabrication of electrodes with enhanced capacitance and improved capacitance retention at high charge–discharge rates and high active mass loadings. The asymmetric devices, containing positive MnO2–MWCNT and negative AC–CB electrodes showed promising performance in a voltage window of 1.6 V. We proposed another novel concept based on electrostatic heterocoagulation of Mn3O4- MWCNT composites in aqueous environment. In this case, various dispersants were selected for adsorption and dispersion of MWCNT and Mn3O4 and this allowed the formation of stable aqueous suspensions of positively charged MWCNT and negatively charged Mn3O4, which facilitated the formation of advanced composites with improved mixing of the components. Testing results showed promising performance of Mn3O4–MWCNT composites for applications in electrodes of electrochemical supercapacitors. Thesis Doctor of Philosophy (PhD)

Electrochemical Supercapacitors (ESs) have been under investigation for decades as advanced energy storage devices. Selection and fabrication of electrode materials are of vital importance for ESs in terms of energy density, power density, cycling stability, specific capacitance, impedance and other capacitive properties. Among various kinds of materials that can be used for electrode fabrication for ES, Polypyrrole (PPy) is found to be promising due to high specific capacitance, high electric conductivity and low cost of fabrication of this material. The addition of advanced anionic dopant enables higher electric conductivity and the combination of PPy and multiwalled carbon nanotubes (MWCNT) enhances cycling stability of polymer backbone during testing process, which improves capacitive behavior of PPy and the composite materials. Since MWCNT has a relatively high aspect ratio making it difficult to be well dispersed, the selection of effective dispersing agents and dispersion of MWCNT consist an important part of this research. In this research, PPy and PPy/MWCNT composite materials were synthesized both in chemical and electrochemical ways. The anionic dopants included 4, 5-Dihydroxy-1, 3-benzenedisulfonic acid disodium salt monohydrate (Tiron) and 4-Formylbenzene-1, i M.A.Sc Thesis Jieming Li McMaster University Materials Science and Engineering 3-disulfonic acid disodium salt hydrate (FDS). And also three kinds of multifunctional dopants were used, that can act as dopant for PPy and dispersing agent for MWCNT at the same time, including Eriochrome Cyanine R (ECR), 4-Amino-5-hydroxy-2, 7-naphthalenedisulfonic acid monosodium salt hydrate (AHN) and 3-Hydroxy-4-nitroso-2, 7-naphthalenedisulfonic acid disodium salt (HNN). The molecular size and functional groups of the anionic dopants and dispersants have great influence on the morphology and capacitive properties of PPy and PPy/MWCNT composites. Higher specific capacitance and excellent capacitance retention were achieved by chemical synthesis, which also offers advantages for large scale production. The results showed that with dopants possessing larger molecular size and multiple charged groups, smaller particle size of PPy and improved capacitive properties could be obtained. The PPy/MWCNT mass ratio of 7 to 3 and Py monomer to dopant molecule molar ratio of 3 to 1 were found to be optimal. The use of Ni foam current collector enabled high mass loading of active materials, which facilitates the fabrication of advanced electrodes for supercapacitors. Thesis Master of Applied Science (MASc)

With a unique blend of power and energy densities, as well as long cycling lives, electrochemical supercapacitors are finding greater application in energy storage solutions. Among candidate materials for supercapacitors, MnO2 has garnered a great deal of attention. However, its low intrinsic electrical conductivity has proven to be a serious hindrance on performance when used in supercapacitor electrodes. Efficient use of conductive additives is a demonstrated, effective method to combat this problem, however there is still a great need for improvement. Two new colloidal processing techniques have been developed to mix chemically synthesized MnO2 and conductive multi-walled carbon nanotubes (MWCNT). The first strategy involved the linking of MnO2 and MWCNT through the formation of a Schiff base. 3,4-dihydroxybenzaldehyde (DB) was used to modify MnO2, while MWCNT were dispersed with the dye New Fuchsin (NF). These compounds were selected due to the presence of molecular features previously identified as conducive to strong adsorption and good colloidal dispersion, as well as the necessary functional groups required to form a Schiff base. The second involved the use of liquid-liquid extraction, primarily in an attempt to prevent post synthesis MnO2 particle agglomeration. Lauryl gallate (LG) was used as an extracting and dispersing agent for MnO2 synthesized via the reaction between aqueous potassium permanganate (KMnO4) and 1-butanol. LG facilitated the co-dispersion and mixing of both MnO2 and MWCNT in the 1-butanol phase. V2O3 was also investigated as a replacement for MnO2, as its high intrinsic electrical conductivity gives it a potential advantage over MnO2. In each of these three projects, electrodes were produced with exceptionally high areal normalized capacitances at high active mass loadings. The MnO2-MWCNT composites were used to fabricate full asymmetric supercapacitor devices that were able to deliver a useable amount of energy. Thesis Master of Applied Science (MASc) The modern world has an insatiable appetite for energy and must have access to it for stationary and mobile applications. To meet this demand, it is of paramount importance to develop new, high performance energy storage technologies. The energy requirements for different applications, however, necessitate storage devices that have suitable properties. The energy stored in a large pool of hot water is not in a suitable form to power a cellphone. The key goal of this work was to further develop one particular energy storage technology, called electrochemical supercapacitors. Novel processing techniques were developed and new materials investigated with the aim of producing supercapacitor electrodes that would exceed the performance of what is already available today. The materials that were produced exhibited very high performance and offered new insight and direction for further research in this exciting field.

Novel electrocchemical and chemical strategies have been developed for the fabrication of functional nanocomposites. New scientific and engineering contribution of this work to colloidal nanotechnology included the development of advanced chelating dispersing agents, such as various small organic molecules and chelating polymers. The unique feature of such dispersion agents is their strong adsorption on the surface of different materials, which allows superior dispersion. The chelating monomers of chelating polymers, such as PAZO and PMSS provided multiple adsorption sites for bonding to metal atoms on the particles surface. We analyzed and developed new fundamental adsorption and dispersion mechanisms. An important finding was the possibility of co-dispersion and co-deposition of advanced materials such as oxides, nitrides, complex oxides and minerals using universal dispersing agents and formation of composites by EPD method. It was found that Caffeic acid (CA) can be used as an efficient dispersing agent for the synthesis of ZnO nanorods of reduced size and a dispersing agent for the EPD of ZnO films. Another important achievement of this work was the application of tannic acid as an efficient capping and dispersing agent for synthesis and EPD of inorganic materials and composites. An important discovery was the use of lauryl gallate dispersant as a reducing agent for the synthesis of AgNp and a vehicle for particle dispersion and extraction in the liquid-liquid extraction method. Further advancements in our new technologies allowed us to develop composite films using anodic EPD using weak polyelectrolytes, such as alginate. The composite coatings exhibited protective and flame retardant properties. We analyzed the deposition mechanisms and kinetics as well as microstructure of the coatings. In another strategy, we developed electrochemical strategies for the deposition of composites, based on strong polyelectrolytes. The approach is based on the EPD of the polyelectrolyte molecules and electrosynthesis of EPD of ceramic particles. The electrostatic heterocoagulation mechanism was proposed for the deposit formation. We investigated the deposition kinetics, composition and microstructure of the composites prepared by the new strategies. The new electrochemical strategies can be used for the deposition of other composites, based on functional polymers with pH independent charge. New methods have been developed for the chemical synthesis of PPy based composites, using PMSS, PMSS–SR11 and PMSS–SR31 as anionic dopants for chemical polymerization and dispersants for MWCNT. The composites showed promising performance for application in electrodes of electrochemical supercapacitors. Good electrochemical performance was achieved at high active mass loadings. The electrodes showed high capacitance, large voltage window and low impedance. The analysis of electrochemical testing results and chemical structure of PMSS, PMSS–SR11 and PMSS–SR31 provided an insight into the influence of the anionic functional groups on the capacitance and capacitance retention a high charge-discharge rates. Thesis Master of Applied Science (MASc)

In this study, polypyrrole (PPy) prepared by chemical and electrochemical polymerization was investigated as the electrode of electrochemical supercapacitor (ES). New strategies were developed for the fabrication of nano-structured PPy and PPy based nano-composites, which included discovery of advanced anionic dopants and multi-functional nano-crystals, and development of co-dispersing agents. These methods improved the capacitive performance and cycle stability of PPy electrodes. The results indicated that high material loading and good capacitance retention of PPy was achieved using an electrochemical polymerization method and Ni plaque as the current collectors. Nano-crystalline (CTA)2S2O8 formed by a chemical precipitation method from solutions, containing anionic oxidant (S2O82-) and cationic surfactant (CTA+), could be used as the oxidant to synthesize PPy nano-fibers. We demonstrated that multi-wall carbon nanotubes (MWCNT) can be efficiently dispersed using such nano-crystals. Application of multi-functional nano-crystals is a conceptually new approach for the fabrication PPy coated MWCNT. Moreover, safranin and malachite green were found as universal dispersing and charging agents for cataphoretic deposition of graphene, MWCNT and PPy nano-fibers. It opens new strategies in colloidal and electrochemical processing of PPy nano-composites for ES electrodes. PPy coated MWCNT, prepared by the multi-functional nano-crystals (CTA)2S2O8, was employed for the fabrication of N-doped activated carbon-coated MWCNT (N-AC-MWCNT). The obtained N-AC-MWCNT was uniformly coated and possessed with high surface area. The use of N-AC-MWCNT enabled the fabrication of ES electrodes with high mass loading and high active material to current collector mass ratio. Symmetric and asymmetric ES cells, fabricated by N-AC-MWCNT and aqueous Na2SO4 electrolyte, showed high specific capacitance, good capacitance retention and large voltage window. The positive electrode of asymmetric ES, MnO2 coated MWCNT, was successfully prepared by the chemical reaction between KMnO4 and N-AC-MWCNT. The problem of degradation of MWCNT was avoided by the use of N-AC as the sacrificial carbon. Significant progress on ES technology has allowed for the development of capacitive dyes removal (CDR) methods using ES devices. In our study, porous carbon materials, N-doped activated carbon coated MWCNT (N-AC-MWCNT) and N-doped activated carbon nano-fibers (N-AC-NF), were developed as the electrodes for CDR applications. The experimental results indicated that capacitive performance of ES cells was influenced by the chemical structure, size, charge-to mass ratio, concentration and redox-active ligands of the dyes. CDR is a promising method for removal of various cationic and anionic dyes, which offers advantages of energy saving and simple electrode regeneration. Thesis Doctor of Philosophy (PhD)

Electrochemical supercapacitors (ECs) attract significant attentions for their unique characteristics of high power density, good cycling capability and low cost. This dissertation will focus on fabrication of composite materials for electrodes and devices of ECs. A conceptually new colloidal approach to the fabrication of metal oxide – multiwalled carbon nanotube (MWCNT) composites is proposed. The heterocoagulation of positively charged oxide nanoparticles and negatively charged MWCNT allows the fabrication of advanced nanocomposites with improved dispersion of individual components. The proof-of-principle was demonstrated by the fabrication of MnO2-MWCNT electrodes for ECs with excellent performance. We proposed another novel concept based on electrostatic heterocoagulation of MnO2-MWCNT composites in aqueous environment. In this case, Benzyldimethylhexadecylammonium chloride (BAC) surfactant and caffeic acid (CA) were selected for adsorption and dispersion of MWCNT and MnO2, respectively, and this allowed the formation of stable aqueous suspensions of positively charged MWCNT and negatively charged MnO2. The asymmetric device showed high capacitance, high powerenergy characteristics with enlarged voltage window of 1.8 V, good capacitance retention at high charge-discharge rates and cyclic stability. A novel capacitive material BiMn2O5 was firstly discovered and synthesized for ECs applications in our studies. The BiMn2O5 nanocrystals were prepared by a hydrothermal method. We demonstrated for the first time that BiMn2O5 – MWCNT composite can be used as a new active material for positive electrodes of ECs. The composite electrode with high mass loading showed a capacitance of 6.0 F cm-2 (540 F cm-3) at a scan rate of 2 mV s-1 and excellent capacitive behavior at high scan rates. As-fabricated device showed good cyclic stability in a voltage window of 1.8 V with energy density of 13.0 Wh L-1 (9.0 Wh kg-1) and power density of 3.6 kW L-1 (2.5 kW kg-1). We firstly discovered that Poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzenesulfonamido]- 1,2-ethanediyl, sodium salt] (PAZO) can be used as an universal dispersant for various materials and its thin film fabricated by electrophoretic deposition (EPD) exhibited photo-induced birefringence. Our new findings indicated that PAZO is good candidate for diverse materials dispersing because it contains diaromatic monomers with salicylate ligands, which can provide multiple adsorption sites for efficient adsorption on particles and impart electrical charges to the particles. Additionally, the use of PAZO polymer offers the advantages of improved steric stabilization. We discovered that Celestine blue (CB) can be developed as an efficient dispersing agent for the nanoparticles. We found that CB includes a catechol ligand, which can provide CB adsorption on inorganic nanoparticles. The relatively large size of the CB molecules is beneficial for the electrosteric dispersion. The benefits of cathodic EPD for nanotechnology were demonstrated by the formation of nanostructured MnO2 films on commercial high surface area current collectors for energy storage in ECs. Thesis Doctor of Philosophy (PhD)

Investigation of flame retardant materials (FRM) identified materials as effective substitutes for halogenated FRM. Many promising materials were tested such as hydrotalcite-type Al–Mg–Zr complex hydroxide, huntite, aluminum hydroxide, hydrotalcite, magnesium carbonate hydroxide pentahydrate, magnesium sulfate heptahydrate, magnesium phosphate hydrate, magnesium chloride hexahydrate, sodium metasilicate pentahydrate, XZO 2022 (Mg3Al) and halloysite. Electrophoretic deposition (EPD) manufacturing technique has been developed for the fabrication of coatings containing the most promising FRM candidates. Identifying charging and dispersion agents, such as poly(4-vinylpyridine-co-butyl methacrylate), humic acid, 2,2′- biquinoline-4,4′-dicarboxylic acid, quaternized hydroxyethylcellulose ethoxylate, 3- phosphonopropionic acid, 16-phosphonohexadecanoic acid, octadecylphosphonic acid, celestine blue, chitosan, to facilitate EPD was of great importance for successful deposition of composite FRM films. The films were investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, thermogravimetric and differential thermal analysis, as well as Fourier Transform Infrared and Ultraviolet-Visible spectroscopy. Thesis Master of Science (MSc) Technology is expanding, as is our understanding of the environmental and health impacts of chemicals. New flame retardant materials (FRM) must be developed to help protect against fire hazards in increasingly complex products, but care must be taken to avoid implementing dangerous chemicals. This work identifies new FRM which can be efficient replacements for widely used, but toxic FRM. FRM can be applied as a coating cheaply, quickly, and evenly onto substrates of even a complex shape. Techniques and additive chemicals are suggested to create advanced FRM coatings

Colloidal processing has been widely used for many industrial application. Electrophoretic deposition (EPD) is an important colloidal technique, which plays an important role in the fabrication of organic-inorganic composites. In this work, advanced dispersing agents with excellent adsorption, dispersion and film forming properties have been developed. The adsorption mechanism and the deposition kinetics of EPD have been studied. It is shown that catechol and salicylic groups of dispersants can form chelation bonding with metal atoms on inorganic particle surface and provide particle charging, dispersion and deposition. The aromatic dispersants can adsorb on carbon nanotubes due to π-π interactions. The long chain ionic polymeric dispersants were investigated, which provide efficient electrosteric stabilization. The film forming properties of dispersants allow dispersants with dispersed materials to deposit and form composite films on the substrate. Universal dispersing agents have been developed for the colloidal processing. These dispersants show possibilities to adsorb and disperse various organic and inorganic materials and pave the way for the fabrication of multi-functional materials for various applications. The composite materials, prepared using new dispersants showed promising corrosion protection of metals, flame retardant and energy storage properties. Thesis Master of Applied Science (MASc)

In this research, different anionic dopants were investigated for the fabrication of polypyrrole (PPy) electrode materials for electrochemical capacitors (ECs). Anionic dopants from catechol, salicylic acid and chromotropic acid family allowed for the formation of adherent PPy thin film on stainless steels current collectors by electropolymerization. Comparison between galvanostatic and pulse electropolymerization of PPy thin films was made. Pulse electropolymerization was found to provide improved impregnation of Ni plaque current collectors and formation of nanostructured coating. The electrodes prepared by pulse electropolymerization showed higher porosity, lower electrical resistance, higher capacitance and improved cyclic stability. In order to overcome the mass loading limitation for thin film PPy electrodes, chemical polymerization of PPy was investigated. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading. Moreover, improved capacitive performance and cyclic stability was obtained for PPy electrodes with high materials loading using new anionic dopants. To further improve the cyclic stability of PPy electrodes, multiwalled carbon nanotubes (MWCNT) were used for the fabrication of PPy-MWCNT composite materials due to their high surface area and excellent conductivity. Different dispersants as well as dispersing methods were studied in order to obtain stable MWCNT suspensions. Among those dispersants, multifunctional anionic dopants were found to benefit the formation of MWCNT suspension as well as the polymerization of PPy. A conceptually new approach has been developed for the fabrication of PPy coated MWCNT based on the use of multifunctional anionic dopants. The use of PPy coated MWCNT allowed excellent electrochemical performance for high active mass loadings, required for commercial EC applications. The electrodes and devices made of PPy coated MWCNT showed high capacitance, good capacitance retention at high charge-discharge rates and good cycling stability. The record high capacitance achieved at high charge-discharge rates is promising for the development of high power ECs. Thesis Doctor of Philosophy (PhD)

Advanced dispersants were discovered for the fabrication of homogeneous suspensions of multi-walled carbon nanotubes (MWCNT), graphene, and manganese dioxide (MnO2) in both ethanol and water. Thin films of MWCNT, graphene, MnO2, composite films of MWCNT-MnO2 and MWCNT-graphene were prepared using electrophoretic deposition (EPD) and electrolytic deposition (ELD) methods. The mechanisms of dispersion and deposition were investigated. Cathodic EPD was achieved for MWCNT and graphene using positively charged dispersants. Co-deposition of MWCNT and MnO¬2 was performed using a co-dispersant, which dispersed both MWCNT and MnO2 in ethanol. Composite films were tested for electrochemical supercapacitor (ES) purposes. Pulse ELD was used to deposit porous MnO2 coatings on Ni foam substrates from KMnO4 solutions. Cathodic deposition offered advantages, compared to anodic deposition, because the problems, related to anodic dissolution of metallic substrates, can be avoided. The pulse ON/OFF times had significant influence on the morphology and structure of MnO2 films, which further determined the capacitive performance. The influence of MnO2 film thickness on specific capacitance was investigated. Porous and conductive vanadium nitride (VN) was synthesized using melamine as a reducing agent. To further improve film conductivity and specific surface area, MWCNT were incorporated into VN matrix during synthesis. VN-MWCNT composite electrodes and VN-MWCNT/MnO2-MWCNT asymmetric supercapacitor cells were fabricated and tested. The electrodes and cells exhibited excellent electrochemical capacitive performance with good cyclic stability. The asymmetric supercapacitor device showed a voltage window up to 1.8 V, which was the combination of voltage window of VN-MWCNT (-0.9 V--0 V) and MnO2-MWCNT (0 V--0.9 V). Polypyrrole (PPy) coated MWCNT were synthesized in ethanol with ammonium peroxydisulfate solution as an oxidant. The effects of dopants to PPy morphology and conductivity was investigated. Dopants with electrochemical active groups were selected for the synthesis of PPy nanoparticles, where dopants also contributed to the capacitance of the polymer based materials. Both PPy-MWCNT/PPY-MWCNT symmetric supercapacitors and VN-MWCNT/PPY-MWCNT asymmetric supercapacitors were fabricated and tested, where the voltage windows were 0.9 V for the former and 1.3 V for the later. The increase of voltage window was ascribed to the asymmetric structure and negative voltage window of VN-MWCNT composite. Thesis Doctor of Philosophy (PhD)

Electrochemical Supercapacitors (ES), also known as Supercapacitor or Ultracapacitor, has been regarded as an advanced electrical energy storage device for decades. Fabrication of advanced electrode materials is of critical importance for advanced ES. Among various materials used for ES electrode, polypyrrole (PPy) is found to be a promising material due to high specific capacitance, good electrical conductivity, low cost and ease of processing. The use of advanced anionic dopants and addition of multiwall carbon nanotube (MWCNT) have been proved an .effective approach towards advanced PPy based ES with improved electrochemical behaviors. In this research, chemical polymerization of PPy powders and PPy/MWCNT composite materials have been successfully accomplished in presence of advanced anionic dopants, including chromotrope families, amaranth, pyrocatechol violet, eriochrome cyanine R and acid fuchsin. The influence of polyaromatic dopants with different molecular size, charges and charge to mass ratios on the microstructure and electrochemical characteristics has been discussed. PPy coated MWCNT with uniform microstructures was successfully achieved in simple chemical methods. The results showed PPy powders with enhanced microstructures and electrochemical behaviors can be obtained by using such advanced anionic dopants. Multi-charged polyaromatic dopants with larger molecular size benefitted PPy powders with smaller particle size, improved specific capacitance, and enhanced cycling stability, at high electrode mass loadings. Moreover, advanced aromatic dispersant and chemical synthesis was proved a simple and effective method for fabrication of PPy/MWCNT composite materials at different PPy/MWCNT mass ratio, among which the powder with PPy/MWCNT mass ratio of 7:3 showed optimum electrochemical performance. Last but not the least, the use of advanced high porosity current collector (Ni foam) allowed high electrode mass loading and good electric conductivity. As a result, advanced PPy/MWCNT composite materials which allows improved electrochemical behaviors, especially at high mass loading, are promising electrode materials for ES. Thesis Master of Applied Science (MASc)

No comments. Thanks. Advanced electrodes based on MnO2 for the electrochemical supercapacitor (ES) application have been fabricated using electrochemical and chemical methods. Electrosynthesis method has been utilized for the in-situ impregnation of manganese dioxide in commercial Ni plaque current collectors. Dipping-reduction, cathodic galvanostatic and reverse pulse electrosynthesis methods were investigated. The material loading was varied by the variation of the number of the dipping-reduction procedures in the chemical precipitation method or by the variation of charge passed in the electrochemical methods. The results obtained by different methods were compared. The dipping-reduction method offered the advantage of higher specific capacitances (SCs) at high scan rates, whereas other methods allowed higher material synthesis rate. Cathodic electrolytic deposition (ELD) has been utilized for the fabrication of Ag-doped MnO2 films. The Ag-doped MnO2 films showed improved capacitive behavior and lower electrical resistance of 0.6 Ohm compared to pure MnO2 films. The highest SC of 770 F g-1 was obtained at a scan rate of 2 mV s-1 in the 0.5 M Na2SO4 electrolyte. Electrodes for ES application were fabricated by cathodic electrodeposition of MnO2 on CNTs, which were grown by chemical vapor deposition on stainless steel meshes. The MnO2-CNT nanocomposites showed excellent capacitive behavior and low electrical resistance of 0.5 Ohm. Electrophoretic deposition (EPD) has been utilized for the deposition of composite MnO2-multiwalled carbon nanotube (MWCNT) films for the ES application. Dopamine (DA), caffeic acid (CA), tyramine (TA), gallic acid (GA), polyacrylic acid (PAA) and pyrocatechol violet (PV) were shown to be effective and universal charging additives, which provide stabilization of MnO2 nanoparticles and MWCNTs in the suspensions. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. We discovered that the number and site of OH group for dispersants were essential for the adsorption on oxide materials, and the number of aromatic ring was important for the adsorption on carbon materials. Pure CNT films were deposited using PV as a dispersant, which was the first time in literature to prepare pure CNT film using a dispersant. SCs decrease with increasing film thickness. SCs of composite MnO2-MWCNT obtained using EPD were in the range of 350-650 F g-1 depending on material loadings. Doctor of Science (PhD)

Electrochemical methods show great promise in the deposition of biocompatible coatings for biomedical applications with advanced functionality. Consequently, methods of creating coatings of bioactive materials, such as halloysite nanotubes (HNT), hydroxyapatite (HA), chitosan, hyaluronic acid (HYH), poly-L-ornithine (PLO) and poly-L-lysine (PLL) and polyacrylic acid (PAA) have been developed through the use of electrophoretic deposition (EPD). The co-deposition of these materials are achieved at voltages ranging from 5 to 20 V on a 304 stainless steel substrate using suspensions of 0.5 and 1.0 gL-1 biopolymer (chitosan, PAA, PLO, PLL) containing 0.3, 0.5 0.6, 1.0 and 2.0 gL-1 bioceramic (HNT, HA). The resulting films were then investigated to further understand the kinetics and mechanics of deposition, determine their properties, and evaluate their suitability for physiological applications. The films were studied using X-Ray Diffraction (XRD), Differential Thermal Analysis and Thermogravimetric Analysis (DTA/TGA), Scanning Electron Microscopy (SEM), Quartz Crystal Microbalance (QCM) and Linear Polarisation. The results indicate that film thickness, composition and morphology can be controlled and modified at will, and that the deposition of composite films, multilayer laminates and functionally graded films are possible. Master of Applied Science (MASc)

Electrochemical deposition methods have been developed for the fabrication of organic － inorganic nanocomposite coatings. The methods are based on electrophoretic deposition of ceramic nanoparticles and polymers. EPD method has been developed for the deposition of nanostructured TiO2 films using new dispersing agents. The stabilization and charging of the nanoparticles in suspensions was achieved using these organic molecules, which belong to catecholate and salicylate families. Anodic deposition was achieved using caffeic acid, 2,3－dihydroxybenzoic acid, 2,6－dihydroxybenzoic acid and 5－sulfosalicylic acid. Cathodic deposition was performed using 2,4 dihydroxycinnamic acid, p－coumaric acid and trans cinnamic acid. The deposition yield has been studied as a function of the additive concentration and deposition time. The deposition mechanism has been investigated. The fundamental adsorption mechanism is based on the complexation of metal ions at the surfaces of oxide nanoparticles. The method enabled the co-deposition of TiO2 and other oxides and the formation of composite films. Electrophoretic deposition method has been used for the deposition of TiO2 nanoparticles modified with organic dyes. Alizarin red, alizarin yellow, pyrocatechol violet and Aurintricarboxylic acid dyes were used for the dispersion and charging of TiO2. The microstructures of the nanocomposite coatings were studied. The deposition yield was investigated under a variety of conditions. Obtained results could pave the way for the fabrication of dye-sensitized TiO2 films. EPD method has also been developed for the fabrication of (Poly[3-(3-N,N-diethylaminopropoxy)thiophene]) PDAOT－TiO2, (polyethylenimine) PEI－TiO2 and PEI－hydrotalcite composite films. The microstructures of the nanocomposite coatings were studied by Scanning Electron Microscopy, Thermogravimetric Analysis, which showed the co－deposition of inorganic nanoparticles and organic polymer. Electrochemical test of the composite film has been conducted. The results showed that PEI film provided corrosion protection of the stainless steel substrates. Master of Science (MSc)