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Due to its low cost, natural abundance, non-toxicity, and high theoretical capacitance, cobalt oxide (CoO) stands as a promising candidate electrode material for supercapacitors. In this study, binder-less molybdenum doped CoO (Mo@CoO) integrated electrodes were one-step fabricated using a simple electric discharge corrosion (EDC) method. This EDC method enables the direct synthesis of Mo@CoO active materials with oxygen vacancy on cobalt substrates, without any pre-made templates, conductive additives, or chemicals. Most importantly, the EDC method enables precise control over the discharge processing parameter of pulse width, which facilitates tailoring the surface morphologies of the as-prepared Mo@CoO active materials. It was found that the fabricated Mo@CoO based symmetric supercapacitor prepared by a pulse width of 24 μs (Mo@CoO-SCs24) achieved a maximum areal capacitance 36.0 mF cm−2 (0.15 mA cm−2), which is 1.83 and 1.97 times higher than that of Mo@CoO-SCs12 and Mo@CoO-SCs36. Moreover, the Mo@CoO-SCs24 devices could be worked at 10 V s−1, which demonstrates their fast charge/discharge characteristic. These results demonstrated the significant potential of the EDC strategy for efficiency fabricating various metal oxide binder-less integrated electrodes for various applications, like supercapacitors, batteries and sensors. [ABSTRACT FROM AUTHOR]

A conceptually new approach is developed for hydrothermal synthesis of nanostructured iron oxides for energy storage in anodes of supercapacitors. The use of biocompatible organic additives facilitates the fabrication of electrodes with enhanced capacitance. The use of amino acids, such as L-histidine (HS), L-lysine (LS) and L-arginine (AR), as capping agents results in the crystallization of antiferromagnetic α-Fe2O3 phases, which show higher capacitance than that of α-Fe2O3 formed without additives using NaOH for pH modification. Surprisingly, the use of meglumine (ML) as an alkalizer–capping agent instead of NaOH results in the fabrication of a ferrimagnetic γ-Fe2O3 phase. The γ-Fe2O3 electrodes prepared using ML show a capacitance of 2.97 F cm−2 from cyclic voltammetry data at 2 mV s−1 and 3.22 F cm−2 from galvanostatic charge–discharge data at 3 mA cm−2 in a potential window of −0.8–0 V in 0.5 M Na2SO4 electrolyte. The high active mass γ-Fe2O3 electrodes, prepared using ML show higher capacitance and lower resistance, compared to the α-Fe2O3 electrodes, prepared using HS, LS and AR. Moreover, the γ-Fe2O3 electrodes prepared using ML exhibit higher capacitance, compared to the literature data for γ-Fe2O3 electrodes, prepared by other methods. The particle size, magnetization and capacitance of the γ-Fe2O3 electrodes can be varied by the variation in synthesis temperature. The obtained γ-Fe2O3 is a promising magnetically ordered pseudocapacitive material for energy storage and other applications based on magnetocapacitive properties. The synthesis method developed in this investigation can be used for the fabrication of other functional nanomaterials. [ABSTRACT FROM AUTHOR]

Transition metal oxides, distinguished by their high theoretical specific capacitance values, inexpensive cost, and low toxicity, have been extensively utilized as electrode materials for high-performance supercapacitors. Nevertheless, their conductivity is generally insufficient to facilitate rapid electron transport at high rates. Therefore, research on bimetallic oxide electrode materials has become a hot spot, especially in the field of micro-supercapacitors (MSC). Hence, this study presents the preparation of bimetallic oxide electrode materials via electro-spark machining (EM), which is efficient, convenient, green and non-polluting, as well as customizable. The fabricated copper-molybdenum bimetallic oxide (MoCuOx) device showed good electrochemical performance under the electrode system. It provided a high areal capacity of 50.2 mF cm−2 (scan rate: 2 mV s−1) with outstanding cycling retention of 94.9% even after 2000 cycles. This work opens a new window for fabricating bimetallic oxide materials in an efficient, environmental and customizable way for various electronics applications. [ABSTRACT FROM AUTHOR]

Vanadium oxides are widely used for microsupercapacitors (MSCs) due to their multiple‐valence and high theoretical capacitance. A conceptually new approach of electric discharge machining (EDM) with computer‐aided control is developed to one‐step fabricate Mo‐doped VO0.2‐based electrodes and devices with designable geometry. The results demonstrate that the Mo@VO0.2 integrated interdigital MSCs (IIMSCs) with the narrowest electrode distance of 300 μm show the best capacitive performance, which is furtherly manifested by the electric field simulation. Moreover, this work concentrates on expounding the relationships between the EDM machining current, surface morphology of Mo@VO0.2, and the capacitive behavior of Mo@VO0.2 IIMSCs. Compared to the machining current of 2 and 3 A, the machining current of 1 A facilitates synthesizing smaller Mo@VO0.2 particles with more porosity and higher surface area and thus achieving a larger capacitance value for Mo@VO0.2 IIMSCs device, which is achieving 32 mF cm−2 at 1 mV s−1, working well up to an ultrahigh scan rate of 30 V s−1, and obtaining a good cyclic stability of 88.61% after 5000 cycles. Moreover, this innovative EDM approach opens a new avenue for one‐step synthesis of various ceramic metal oxides for various microdevices such as microbatteries and microsensors. [ABSTRACT FROM AUTHOR]

This investigation focused on the fabrication of ceramic ferrimagnetic CuFe2O4–conductive polypyrrole (PPy) composites for energy storage. CuFe2O4 with a crystal size of 20–30 nm and saturation magnetization of 31.4 emu g−1 was prepared by hydrothermal synthesis, and PPy was prepared by chemical polymerization. High-active-mass composite electrodes were fabricated for energy storage in supercapacitors for operation in a sodium sulfate electrolyte. The addition of PPy to CuFe2O4 resulted in a decrease in charge transfer resistance and an increase in capacitance in the range from 1.20 F cm−2 (31 F g−1) to 4.52 F cm−2 (117.4 F g−1) at a 1 mV s−1 sweep rate and from 1.17 F cm−2 (29.9 F g−1) to 4.60 F cm−2 (120.1 F g−1) at a 3 mA cm−2 current density. The composites showed higher capacitance than other magnetic ceramic composites of the same mass containing PPy in the same potential range and exhibited improved cyclic stability. The magnetic behavior of the composites was influenced by the magnetic properties of ferrimagnetic CuFe2O4 and paramagnetic PPy. The composites showed a valuable combination of capacitive and magnetic properties and enriched materials science of magnetic supercapacitors for novel applications based on magnetoelectric and magnetocapacitive properties. [ABSTRACT FROM AUTHOR]

With the increasing market demands for wearable and portable electronic devices, binary metal oxides (BMOs) with a remarkable capacity and good structure stability have been considered as a promising candidate for fabricating coplanar micro-supercapacitors (CMSCs), serving as the power source. However, the current fabrication methods for BMO microelectrodes are complex, which greatly hinder their further development and application in BMO CMSCs. Herein, the one-step fabrication of 2.5D CuMoOx-based CMSCs (CuMoCMSCs) has been realized by numerically controlled electric discharge machining (NCEDM) for the first time. In addition, the controllable capacity of CuMoCMSCs has been achieved by adjusting the NCEDM-machining voltage. The CuMoCMSCs machined by a machining voltage of 60 V (CuMoCMSCs60) showed the best performance. The fabricated CuMoCMSCs60 with binary metal oxides could operate at an ultra-high scanning rate of 10 V s−1, and gained a capacity of 40.3 mF cm−2 (1.1 mA cm−2), which is more than 4 times higher than that of MoOx-based CMSCs (MoCMSCs60) with a single metal oxide. This is because CuMoOx BMOs materials overcome the poor electroconductivity problem of the MoOx single metal oxide. This one-step and numerically controlled fabrication technique developed in this research opens a new vision for preparing BMO materials, BMO microelectrodes, and BMO microdevices in an environmental, automatic, and intelligent way. [ABSTRACT FROM AUTHOR]

Cobalt oxide-based in-plane microsupercapacitors (IPMSCs) stand out as a favorable choice for various applications in energy sources for the Internet of Things (IoT) and other microelectronic devices due to their abundant natural resources and high theoretical specific capacitance. However, the low electronic conductivity of cobalt oxide greatly hinders its further application in energy storage devices. Herein, a new manufacturing method of electric discharging machining (EDM), which is simple, safe, efficient, and environment-friendly, has been developed for synthesizing Mo-doped and oxygen-vacancy-enriched Co-CoO (Mo@Co-CoO) integrated microelectrodes for efficiently constructing Mo@Co-CoO IPMSCs with customized structures in a single step for the first time. The Mo@Co-CoO IPMSCs with three loops (IPMSCs3) exhibited a maximum areal capacitance of 30.4 mF cm−2 at 2 mV s−1. Moreover, the Mo@Co-CoO IPMSCs3 showed good capacitive behavior at a super-high scanning rate of 100 V s−1, which is around 500–1000 times higher than most reported CoO-based electrodes. It is important to note that the IPMSCs were fabricated using a one-step EDM process without any assistance of other material processing techniques, toxic chemicals, low conductivity binders, exceptional current collectors, and conductive fillers. This novel fabrication method developed in this research opens a new avenue to simplify material synthesis, providing a novel way for realizing intelligent, digital, and green manufacturing of various metal oxide materials, microelectrodes, and microdevices. [ABSTRACT FROM AUTHOR]

Cyrene is a new biodegradable solvent, which represents a green alternative to many traditional toxic solvents for advanced polymers. Therefore, this investigation is motivated by interest in applications of Cyrene for polymer processing. The feasibility of solubilization of polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) in Cyrene is demonstrated. The ability to form relatively concentrated solutions of the high molecular mass polymers is an important factor for the formation of PMMA and PEMA films by a dip coating method. It was found that the polymer coatings provide corrosion protection of stainless steel in 30 g L−1 NaCl solutions. Another important finding is that the use of Cyrene facilitates the fabrication of stable suspensions of hydroxyapatite (HAp), microdiamond, and nanodiamond particles. Therefore, the problems of the dispersant selection for dispersion of chemically inert diamond and development of biocompatible dispersants are avoided using Cyrene. For the fabrication of composite films, HAp nanorods with reduced particle size are obtained using rutin as a chelating capping agent. Composite films containing HAp, microdiamond and nanodiamond in the PMMA or PEMA matrix are obtained. The composite films are promising for biomedical applications. It was found that the film morphology, composition and microstructure are influenced by the solvent–particle–polymer interactions and processing conditions. [ABSTRACT FROM AUTHOR]

This investigation is inspired by multifunctional properties and biocompatibility of meglumine (ML) for new applications in colloidal processing of materials. The application of ML as both an alkalizer and capping agent enabled the fabrication of hydroxyapatite (HA) nanoparticles. The morphologies of HA nanoparticles prepared using ML alkalizer/capping agent or an inorganic alkali are compared. The use of ML allowed particle size reductions and offers multiple processing and environmental benefits. The feasibility of solubilization of alginic acid (ALH) biopolymer and glycyrrhetinic acid (GAH) drug in water using ML is demonstrated. For the first time, electrophoretic deposition (EPD) of ALH and GAH from their solutions is performed. The solubilization and EPD mechanisms are discussed, and the film deposition yield is analyzed. The use of ML as alkalizer, solubilizer, capping and dispersing agent facilitates the fabrication of ALH-GAH, ALH-HA, ALH-silica, and ALH-titania films by EPD. Changes in the EPD bath composition allows for the variation of the composition and microstructure of the films. The benefits of the suggested method for colloidal processing of composites are discussed. The use of ML opens an avenue for synthesis of other inorganic nanomaterials of controlled size, nanoparticle dispersion, solubilization, and EPD of other polymers, drugs, and composites. [ABSTRACT FROM AUTHOR]

This study is inspired by the importance of advanced composites, combining spontaneous magnetization with electrical charge storage properties. It is focused on the investigation of magnetically hard SrFe12O19 (SFO) material and its composites with polypyrrole (PPy). For the first time, an organic surfactant–charge transfer mediator and high-energy ball milling (HEBM) were applied to the preparation of high-active-mass SFO composite electrodes. An important finding was the ability to achieve enhanced capacitance of SFO and its composites in a negative range of electrode potentials in an electrolyte. The benefits of the sodium sulfate electrolyte and the charge storage mechanism are discussed. Another important finding was the synergy of the properties of SFO and PPy, which allowed the preparation of highly capacitive conductive composites. The effects of HEBM and the SFO content in the composites on the capacitive properties were studied. Magnetic measurements revealed the effect of HEBM on the magnetic properties and demonstrated good magnetic properties of the composites, which also exhibited advanced capacitive properties. The composites were utilized for the manufacturing of an asymmetric device, which exhibited high capacitive properties at an applied voltage of 1.5 V. [ABSTRACT FROM AUTHOR]

Ferromagnetic perovskite La0.65Sr035MnO3 (LSM) is prepared as an active material for electrodes with high active mass loading of 40 mg cm−2 for applications in supercapacitors. The experimental approach of this investigation is based on the use of high energy ball milling and application of gallocyanine as an advanced catecholate-type chelating dispersant. We report a high capacitance of 3.75 F cm−2 from cyclic voltammetry data at 2 mV s−1 and 4.59 F cm−2 from chronopotentiometry data at 3 mA cm−2 for LSM. The electrodes show nearly ideal pseudocapacitive behavior and a low resistance. The capacitance of ferromagnetic perovskite LSM electrodes in a positive potential range is higher or on a par with capacitances of spinel ferrimagnetic electrodes for operation in a negative potential range in the same electrolyte. Cycling at fast charge–discharge rates shows capacitance increase, which is attributed to morphology changes and oxidation of Mn ions. The LSM electrodes were used for application in magnetic asymmetric devices, containing ferromagnetic LSM cathodes and ferrimagnetic CoFe2O4 based anodes with high active mass for operation in a neutral Na2SO4 electrolyte. [ABSTRACT FROM AUTHOR]

This investigation is motivated by an interest in multiferroic BaFe12O19 (BFO), which combines advanced ferrimagnetic and ferroelectric properties at room temperature and exhibits interesting magnetoelectric phenomena. The ferroelectric charge storage properties of BFO are limited due to high coercivity, low dielectric constant, and high dielectric losses. We report the pseudocapacitive behavior of BFO, which allows superior charge storage compared to the ferroelectric charge storage mechanism. The BFO electrodes show a remarkably high capacitance of 1.34 F cm−2 in a neutral Na2SO4 electrolyte. The charging mechanism is discussed. The capacitive behavior is linked to the beneficial effect of high-energy ball milling (HEBM) and the use of an efficient dispersant, which facilitates charge transfer. Another approach is based on the use of conductive polypyrrole (PPy) for the fabrication of PPy-BFO composites. The choice of new polyaromatic dopants with a high charge-to-mass ratio plays a crucial role in achieving a high capacitance of 4.66 F cm−2 for pure PPy electrodes. The composite PPy-BFO (50/50) electrodes show a capacitance of 3.39 F cm−2, low impedance, reduced charge transfer resistance, enhanced capacitance retention at fast charging rates, and good cyclic stability due to the beneficial effect of advanced dopants, HEBM, and synergy of the contribution of PPy and BFO. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effectiveness of murexide for surface modification of Fe 3 O 4 nanoparticles to enhance the performance of multiwalled carbon nanotube- Fe 3 O 4 supercapacitor anodes. Our experimental results demonstrate significant improvements in electrode performance when murexide is used as a capping or dispersing agent compared to the case with no additives. When murexide is used as a capping agent, we report a capacitance of 4.2 F cm - 2 from cyclic voltammetry analysis with good capacitance retention at high scan rates. From impedance measurements, we reveal a substantial decrease in the real part of impedance for samples prepared with murexide, indicating easier charge transfer at more negative electrode potentials, and reinforcing the role of murexide as a capping agent and charge transfer mediator. Density functional theory is used to investigate interactions between the murexide adsorbate and the Fe 3 O 4 (001) surface, with a specific emphasis on adsorption strength, charge transfer, and electronic properties. This theoretical investigation uncovers a strong adsorption enthalpy of − 4.5 eV and allows us to identify the nature of chemical bonds between murexide and the surface, with significant charge transfer taking place between the Fe 3 O 4 surface and murexide adsorbate. The transfer of electrons from the Fe 3 O 4 surface to murexide is recognized as a vital component of the adsorption process. By examining the bonding nature of murexide on Fe 3 O 4 , this research study uncovers insights and proposes a novel bonding configuration of murexide that incorporates a combination of bridging and chelating bonding. [ABSTRACT FROM AUTHOR]

This investigation addresses increasing interest in advanced composite materials, combining capacitive properties and spontaneous magnetization for energy storage applications in supercapacitors. The capacitive properties of ferrimagnetic NiFe2O4 (NFO) spinel nanoparticles with magnetization of 30 emu g−1 were enhanced using high-energy ball-milling and the use of advanced dispersant, which facilitated charge transfer. NFO electrodes with an active mass of 40 mg cm−2 showed a capacitance of 1.46 F cm−2 in 0.5 M Na2SO4 electrolyte in a negative potential range. The charging mechanism in the negative potential range in Na2SO4 electrolyte was proposed. NFO was combined with conductive polypyrrole polymer for the fabrication of composites. The analysis of the capacitive behavior of the composites using cyclic voltammetry, chronopotentiometry and impedance spectroscopy at different electrode potentials revealed synergy of contributions of NFO and PPy. The highest capacitance of 6.64 F cm−2 was obtained from cyclic voltammetry data. The capacitance, impedance, and magnetic properties can be varied by variation of electrode composition. Composite electrodes are promising for application in anodes of asymmetric magnetic supercapacitors for energy storage and magnetically enhanced capacitive water purification devices. [ABSTRACT FROM AUTHOR]

This study is focused on overcoming obstacles in the implementation of metallic Zn for zinc‐ion batteries. The major limiting factors of Zn anodes include dendrite growth, hydrogen evolution, and by‐product formation. Herein, the challenges are addressed by the application of a redox‐active electrode‐electrolyte interphase. Cationic polypyrrole(PPy)/anionic Tiron anolyte is formulated as the mixed conducting interphase to push the limits of zinc‐based energy storage. The doping/de‐doping behavior of PPy stimulates the surface adsorption/desorption of Tiron attributed to the ion‐induced nucleation. Testing results show that PPy as a passivating corrosive‐resistant layer improves the interfacial stability of Zn metal; while releasing the redox‐active anolyte boosts the charge transfer of cells by the phenol‐quinone transformations. The Zn//Zn cells demonstrate an improved life from 50 to 2500 cycles with a reduced overpotential at 2 mA cm−2 and 1 mAh cm−2. In situ UV–vis spectroscopic measurements, combined with density functional theory calculations, address the redox mechanisms of PPy/Tiron anolyte. The testing of α‐MnO2//Zn cells shows that the PPy/Tiron anolyte exhibits enhanced capacity and rate performance due to the pseudocapacitive effects. This study unveils a conceptually new approach based on the modification of conducting polymer with redox‐active dopants toward the fabrication of high‐performance Zn‐anolyte batteries. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) signal transduction has emerged as a powerful technique for ultrasensitive biosensing with a low background in complex media. However, it remains challenging to create PEC biosensors found on stable materials that are easily biofunctionalized. Herein, we report the development of a one-pot synthesis method for TiO2 nanoparticles (NPs) decorated with Ag NPs. In this nanomaterial synthesis process, TiO2 NPs are modified with hematoxylin (HTX) dye to achieve enhanced photoreduction and direct nucleation of Ag NPs. The resulting TiO2/HTX/Ag NP heterostructure showed significantly enhanced photocurrent generation, necessary for achieving high sensitivity in PEC biosensing, through the combined effects of plasmon resonance and photoelectron injection. TiO2/HTX/Ag NP is very easily biofunctionalized through thiol–metal complexation. This was taken as an advantage to create a multiplexing PEC microRNA sensor for the analysis of urine samples, which demonstrated a low limit of detection of 172 fM and a high dynamic range of 100 fM–100 nM, while showing a high degree of specificity. [ABSTRACT FROM AUTHOR]

There is a need for point‐of‐care bacterial sensing and identification technologies that are rapid and simple to operate. Technologies that do not rely on growth cultures, nucleic acid amplification, step‐wise reagent addition, and complex sample processing are the key for meeting this need. Herein, multiple materials technologies are integrated for overcoming the obstacles in creating rapid and one‐pot bacterial sensing platforms. Liquid‐infused nanoelectrodes are developed for reducing nonspecific binding on the transducer surface; bacterium‐specific RNA‐cleaving DNAzymes are used for bacterial identification; and redox DNA barcodes embedded into DNAzymes are used for binding‐induced electrochemical signal transduction. The resultant single‐step and one‐pot assay demonstrates a limit‐of‐detection of 102 CFU mL−1, with high specificity in identifying Escherichia coli amongst other Gram positive and negative bacteria including Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus subtilis. Additionally, this assay is evaluated for analyzing 31 clinically obtained urine samples, demonstrating a clinical sensitivity of 100% and specify of 100%. When challenging this assay with nine clinical blood cultures, E. coli‐positive and E. coli‐negative samples can be distinguished with a probability of p < 0.001. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the need in the development of manganese oxide cathodes for supercapacitors with high capacitance at high charge–discharge rates and enhanced capacitance retention in a wide range of charge–discharge rates. It also addresses the challenge of eliminating the time-consuming activation procedure, which limits the applications of Mn3O4 cathodes. The new approach is based on the use of environmentally friendly and biocompatible pH modifiers–dispersants, such as polyethylenimine (PEI) and meglumine (MG) for hydrothermal synthesis. In this approach, the use of inorganic alkalis is avoided. We demonstrate the benefits of this approach for the fabrication of manganese oxide nanoparticles, such as Mn-PEI and Mn-MG. Electrodes with a high active mass of 40 mg cm−2 are fabricated and electrochemically tested in 0.5 M Na2SO4 electrolyte. The method of electrode material fabrication offers benefits for the accelerated electrode activation procedure, which is practically eliminated for Mn-MG electrodes. The Mn-MG electrodes showed a remarkably high capacitance of 3.68 F cm−2 (93.19 F g−1) at a sweep rate of 100 mV s−1 and a high capacitance retention of 90.6% in the CV sweep range of 1–100 mV s−1. [ABSTRACT FROM AUTHOR]

Ti3C2Tx–Fe3O4–carbon nanotube composites were prepared for electrochemical energy storage in the negative electrodes of supercapacitors. The electrodes show a remarkably high areal capacitance of 6.59 F cm−2 in a neutral Na2SO4 electrolyte, which was obtained by the development of advanced nanofabrication strategies and due to the synergistic effect of the individual components. Enhanced capacitance was achieved using the in-situ synthesis method for the Fe3O4 nanoparticles. The superparamagnetic behavior of the Fe3O4 nanoparticles facilitated the fabrication of electrodes with a reduced binder content. Good mixing of the components was achieved using a celestine blue co-dispersant, which adsorbed on the inorganic components and carbon nanotubes and facilitated their co-dispersion and mixing. The capacitive behavior was optimized by the variation of the electrode composition and mass loading in a range of 30–45 mg cm−2. An asymmetric device was proposed and fabricated, which contained a Ti3C2Tx–Fe3O4–carbon nanotube negative electrode and a polypyrrole–carbon nanotube positive electrode for operation in an Na2SO4 electrolyte. The asymmetric supercapacitor device demonstrated high areal capacitance and excellent power-density characteristics in an enlarged voltage window of 1.6 V. This investigation opens a new avenue for the synthesis and design of MXene-based asymmetric supercapacitors for future energy storage devices. [ABSTRACT FROM AUTHOR]

Pseudocapacitive (PC) materials are under investigation for energy storage in supercapacitors, which exhibit exceptionally high capacitance, good cyclic stability, and high power density. The ability to combine high electrical capacitance with advanced ferrimagnetic or ferromagnetic properties in a single material at room temperature opens an avenue for the development of advanced magnetically ordered pseudocapacitive (MOPC) materials. This review covers materials science aspects, charge storage mechanisms, magnetocapacitance, and magnetoelectric (ME) phenomena in MOPC materials. Recent studies demonstrate high PC properties of advanced ferrimagnetic materials, such as spinel ferrites and hexagonal ferrites. Of particular importance is the discovery of PC properties of perovskite-type manganites, which exhibit room temperature ferromagnetism and giant negative magnetoresistance. The coupling of high capacitance and magnetization in MOPC provides a platform for strong ME interactions. Various strategies are used for manipulation of electrical capacitance/magnetization of MOPC by a magnetic field/electrode potential. Magnetocapacitance studies show significant increase in capacitance of MOPC under the influence of a magnetic field. Moreover, the application of a magnetic field results in enhanced energy density and power density, reduction of resistance, and improvement of cyclic stability. Such findings offer a potential of a breakthrough in the development of advanced supercapacitors. High magnetocapacitance and ME phenomena are linked to the influence of magnetic fields on electrolyte diffusion, structure of electrical double layer, charge transfer resistance, and variation of conductivity and magnetization of MOPC materials, which facilitate charge/discharge behavior. Various applications of ME effect in MOPC are discussed. Moreover, advantages of magnetocapacitive MOPC are described for applications in electronic and spintronic devices, supercapacitors, and devices for magnetically enhanced capacitive deionization of water. [ABSTRACT FROM AUTHOR]

This investigation is motivated by interest in nanostructured FeOOH anodes for aqueous asymmetric supercapacitors operating in Na2SO4 electrolyte. The research goal is the fabrication of anodes with high active mass loading of 40 mg cm−2, high capacitance and low resistance. The influence of high-energy ball milling (HEBM), capping agents and alkalizer on the nanostructure and capacitive properties is investigated. HEBM promotes the crystallization of FeOOH, which results in capacitance reduction. Capping agents from the catechol family, such as tetrahydroxy-1,4-benzoquinone (THB) and gallocyanine (GC), facilitate the fabrication of FeOOH nanoparticles, eliminate the formation of micron size particles and allow the fabrication of anodes with enhanced capacitance. The analysis of testing results provided insight into the influence of the chemical structure of the capping agents on nanoparticle synthesis and dispersion. The feasibility of a conceptually new strategy for the synthesis of FeOOH nanoparticles is demonstrated, which is based on the use of polyethylenimine as an organic alkalizer-dispersant. The capacitances of materials prepared using different nanotechnology strategies are compared. The highest capacitance of 6.54 F cm−2 is obtained using GC as a capping agent. The obtained electrodes are promising for applications as anodes for asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

This investigation is motivated by increasing interest in polymer-diamond coatings for biomedical applications in implants and sensors. A conceptually new strategy is based on the feasibility of solubilisation of polyethyl methacrylate (PEMA) in isopropanol using 18β-glycyrrhetinic acid (GRA) and rhamnolipids (RLP) as solubilising agents. This approach offers benefits for biomedical applications by avoiding the use of traditional toxic solvents for PEMA dissolution. The ability to obtain concentrated solutions of high molecular mass polymer is a crucial factor for the development of a dip coating method. Potentiodynamic and impedance spectroscopy studies indicate that PEMA films provide corrosion protection of stainless steel in 3% NaCl solutions. The use of GRA facilitates the fabrication of films with improved protective properties. PEMA films are obtained as monolayers or multilayers of controlled film mass. Another important finding is a good dispersion of chemically inert microdiamond and nanodiamond particles using GRA and RLP. For the first time composite PEMA-diamond films are obtained using GRA and RLP as solubilising agents for PEMA and dispersing agents for diamonds in isopropanol solvent. The detailed analysis of film microstructures provides an insight into the influence of chemical structure of GRA and RLP on their interactions with PEMA and diamonds. Moreover, microstructure analysis indicates that such interactions are important for preventing defects in the composite films. The benefits of steroid-like dispersants are discussed. Composite films are obtained as monolayers with different diamond content or PEMA-diamond multilayers of different composition and film mass. The method represents a versatile strategy for the fabrication of alternating PEMA/PEMA-diamond multilayers. The benefits of the obtained microstructures for biomedical applications are discussed. The approach developed in this investigation opens an avenue for the fabrication of other polymer coatings containing various functional materials. [ABSTRACT FROM AUTHOR]

Nanotechnology offers powerful strategies for the synthesis of advanced materials for supercapacitors. It is hypothesized that the size reduction of Mn3O4 nanoparticles can eliminate time-consuming electrochemical activation and increase the electrochemical pseudocapacitance of this material. Moreover, due to the redox properties and specific features of its chemical synthesis procedure, Mn3O4 can potentially outperform other promising cathode materials for energy storage in supercapacitors. A facile room temperature method to fabricate Mn3O4 nanoparticles is described, which is based on the application of advanced capping agents (CAs) for nanofabrication. Building on the strong adsorption power of the catechol ligand, we utilize tetrahydroxy-1,4-quinone, catechin, and gallocyanine as CAs for the preparation of Mn3O4. The use of the catecholate molecules as CAs for chemical precipitation facilitates the preparation of Mn3O4 platelet nanoparticles with a typical size of 5 nm. The reduction of the particle size allows the fabrication of advanced Mn3O4 multiwalled carbon nanotube cathodes with 40 mg cm–2 active mass (AM), which show a significant increase in capacitance in a 0.5 M Na2SO4 electrolyte. The highest capacitances of 7.03 F cm–2 (175.8 F g–1) at a potentiodynamic sweep rate of 2 mV s–1 and 9.13 F cm–2 (228.3 F g–1) at a constant current density of 3 mA cm–2 are obtained at a low impedance using gallocyanine as a CA. Obtained electrodes outperform MnO2-based cathodes of similar mass. Another important finding is the possibility to avoid the time-consuming activation process for Mn3O4-based electrodes. Analysis of the testing results provides evidence of the influence of the CA structure on the electrode performance. The results of this investigation pave the way for the application of Mn3O4 in advanced high-AM supercapacitor cathodes. [ABSTRACT FROM AUTHOR]

The full potential of Fe3O4 for supercapacitor applications can be achieved by addressing challenges in colloidal fabrication of high active mass electrodes. Exceptional adsorption properties of catecholate-type 3,4-dihydroxybenzoic acid (DHBA) molecules are explored for surface modification of Fe3O4 nanoparticles to enhance their colloidal dispersion as verified by sedimentation test results and Fourier-transform infrared spectroscopy measurements. Electrodes prepared in the presence of DHBA show nearly double capacitance at slow charging rates as compared to the control samples without the dispersant or with benzoic acid as a non-catecholate dispersant. Such electrodes with active mass of 40 mg cm−2 show a capacitance of 4.59 F cm−2 from cyclic voltammetry data at a scan rate of 2 mV s−1 and 4.72 F cm−2 from galvanostatic charge–discharge data at a current density of 3 mA cm−2. Experimental results are corroborated by density functional theory (DFT) analysis of adsorption behaviour of DHBA and benzoic acid at the (001) surface of Fe3O4. The strongest adsorption energy (ca. −1.8 eV per molecule) is due to the catechol group of DHBA. DFT analysis provides understanding of the basic mechanism of DHBA adsorption on the surface of nanoparticles and opens the way for fabrication of electrodes with high capacitance. [ABSTRACT FROM AUTHOR]

One method for reliable on-site detection of water pollutants is to use highly sensitive and specific nonenzymatic electrochemical sensors containing agglomeration-free detecting agents specific to the water pollutants. We describe a facile and highly effective method to fabricate electrocatalytic electrodes with ZrO2, MnO2, and MgO that are well dispersed within the ink used to print these electrodes. The inorganic metal oxides serve as detecting agents with specific affinity toward fenitrothion (FT, an organophosphate), lead (Pb2+, a heavy-metal ion), and nitrite (NO2–, a nutrient), respectively. Our bioinspired method utilizes a catechol molecule, 3,4-dihydroxybenzaldehyde (DHBA), and film-forming polymer chitosan (CHIT). Redox-active DHBA strongly adsorbs the metal oxide through bidentate bonding, and CHIT-linked DHBA assists in stable film formation. This metal oxide surface modification through the DHBA-CHIT chemistry enhances the electronic, film-forming, and nanoparticle dispersing properties of the electrode modifying ink. The ink is drop-cast on nitrogen–sulfur co-doped activated carbon-coated carbon nanotubes (NS-AC-MWCNT) on a modified glassy carbon electrode (GCE). The resulting sensor consists of metal oxide as a detecting agent and NS-AC-MWCNT as a supportive electrode. The technique enhances the total surface area of the X-DHBA-CHIT/NS-AC-MWCNT/GCE electrode (where X denotes ZrO2, MnO2, or MgO) and its electrocatalytic properties. The ZrO2-DHBA-CHIT/NS-AC-MWCNT/GCE sensor has an excellent detection limit of 1.69 nM for 0.01–40 μM FT, which exceeds that of enzyme-based sensing. It is reliable for lake water with a detection limit of 11.3 nM FT, attributed to its excellent antifouling ability, and has negligible interference from commonly found chemicals in drinking water. Similarly, the MnO2-DHBA-CHIT/NS-AC-MWCNT/GCE and MgO-DHBA-CHIT/NS-AC-MWCNT/GCE sensors show excellent Pb2+ and NO2– electrochemical detection compared to unmodified electrodes. This simple, effective, non-hazardous methodology can be extended to modify the surfaces of other metal or metal oxide detecting agents. [ABSTRACT FROM AUTHOR]

Composite polymer-ceramic films are prepared from colloidal suspensions by electrophoretic deposition (EPD). Co-deposition of ferrimagnetic CuFe2O4 with ferroelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer is achieved using a co-dispersant, which is also used for the preparation of PVDF-HFP particles. The mechanism of co-dispersant adsorption on CuFe2O4 and PVDF-HFP in colloidal suspensions is analyzed. Electrochemical studies of CuFe2O4 reveal good pseudocapacitive properties of this material in a negative potential range, which make it a material of choice for magnetocapacitive devices. A capacitance of 1.72 F cm−2 (43.1 F g−1) is observed at 2 mV s−1 for pure material in a neutral Na2SO4 electrolyte. The microstructure and composition of PVDF-HFP-CuFe2O4 films are analyzed. Composite films show ferrimagnetic properties, which are analyzed in a wide temperature range. EPD method represents a versatile strategy for the fabrication of composite films based on functional properties of CuFe2O4 and PVDF-HFP. [ABSTRACT FROM AUTHOR]

This investigation, which is motivated by promising pseudocapacitive properties of Mn3O4 for energy storage in cathodes of supercapacitors, addresses the need to understand both the activation and the charge storage mechanisms of Mn3O4 electrodes. Specific activation protocols are shown to result in significant capacitance increase during cycling. For the first time scanning transmission X-ray microscopy (STXM) is used for analysis of Mn3O4 activation. STXM analyses at the Mn 2p and O 1s edges provide chemical mapping of different oxidation states with high spatial resolution. Mn3O4-carbon nanotube composite electrodes with commercially important high active mass loading of 40 mg cm−2 are prepared using quercetin dispersant. The catecholate type polyaromatic quercetin facilitates co-dispersion of Mn3O4 with carbon nanotubes and allows enhanced electrode performance at high active mass loadings. Cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge are used for the capacitance monitoring during electrode activation. Two strategies are used for electrode activation in Na2SO4 electrolyte: electrochemical cycling at different scan rates and continuous cycling at a fixed scan rate. The capacitance variations are linked to STXM observations, which show gradual oxidation of Mn3O4 to form MnO2 on the particle surface and in the bulk. The pseudocapacitive charge storage mechanism involves in situ oxidation of Mn3O4 and redox reactions of Mn4+/Mn3+ species on the particle surface and in the bulk. [ABSTRACT FROM AUTHOR]

This investigation is motivated by increasing interest in the development of magnetically ordered pseudocapacitors (MOPC), which exhibit interesting magnetocapacitive effects. Here, advanced pseudocapacitive properties of magnetic CuFe2O4 nanoparticles in negative potential range are reported, suggesting that CuFe2O4 is a promising MOPC and advanced negative electrode material for supercapacitors. A high capacitance of 2.76 F cm−2 is achieved at a low electrode resistance in a relatively large potential window of 0.8 V. The cyclic voltammograms and galvanostatic charge–discharge data show nearly ideal pseudocapacitive behavior. Good electrochemical performance is achieved at a high active mass loading due to the use of chelating molecules of ammonium salt of purpuric acid (ASPA) as a co-dispersant for CuFe2O4 nanoparticles and conductive multiwalled carbon nanotube (MCNT) additives. The adsorption of ASPA on different materials is linked to structural features of ASPA, which allows for different interaction and adsorption mechanisms. The combination of advanced magnetic and pseudocapacitive properties in a negative potential range in a single MOPC material provides a platform for various effects related to the influence of pseudocapacitive/magnetic properties on magnetic/pseudocapacitive behavior. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the numerous advantages of electrophoretic deposition (EPD) for the fabrication of polyvinylidene fluoride (PVDF) and composite coatings and the various applications of such coatings. It is demonstrated that gallic acid (GA), caffeic acid (CFA), cholic acid (CA) and 2,3,4 trihydroxybenzoic acid (THB) can be used as charging and dispersing agents for the EPD of PVDF. The deposition yield of PVDF increases in the following order: THB < CFA < CA < GA. Test results indicate that the chemical structure of the dispersants exerts influence on the deposition efficiency. Potentiodynamic and impedance spectroscopy studies show the corrosion protection properties of PVDF coatings. GA is used for the co-EPD of PVDF with nanosilica and micron-size silica. The silica content in the composite coatings is varied by the variation of silica content in the suspensions. The ability to use GA as a charging and dispersing agent for the co-EPD of materials of different types paves the way for the fabrication of advanced organic–inorganic composites using EPD. [ABSTRACT FROM AUTHOR]

Polymethylmethacrylate (PMMA) is a material of choice for many biomedical coating applications. However, such applications are limited due to the toxicity of the traditional solvents used for the solution processing of PMMA coatings and composites. This problem is addressed using an isopropanol-water co-solvent, which allows for the dissolution of high molecular mass PMMA and the fabrication of coatings by a dip-coating method from concentrated PMMA solutions. The use of the co-solvent offers a versatile strategy for PMMA solubilization and coating deposition, despite the insolubility of PMMA in water and isopropanol. Composite coatings are obtained, containing hydroxyapatite, silver oxide, zinc oxide, micron size silica and nanosilica. Such coatings are promising for the manufacturing of implants with enhanced biocompatibility, bioactivity and antimicrobial properties and the fabrication of biosensors. Ibuprofen, tetracycline and amoxicillin are used as model drugs for the fabrication of PMMA-drug composite coatings for drug delivery. The microstructure and composition of the coatings are analyzed. The versatile dip-coating method of this investigation provides a platform for various biomedical applications. [ABSTRACT FROM AUTHOR]

A biomimetic approach is described for the fabrication of poly(ethyl methacrylate) (PEMA) coatings by a dip coating method. In the proposed approach, bile acids, such as cholic acid and lithocholic acid, are used as solubilizing agents for PEMA in isopropanol. For the first time, PEMA coatings are fabricated from solutions in isopropanol avoiding the use of traditional toxic solvents. The feasibility of fabricating concentrated solutions of high molecular mass PEMA is a key factor for the deposition. The coatings can be obtained as monolayers or multilayers of controlled coating mass. The analysis of deposition yield data and chemical structures of the bile acids provides an insight into the deposition mechanism. The PEMA coatings provide corrosion protection of stainless steel. Building on advanced properties of bile acids, as natural dispersants, composite coatings containing various bioceramics, such as hydroxyapatite, silica, and titania in the PEMA matrix, are obtained. Tetracycline is used as a model drug for the fabrication of drug-containing PEMA coatings. It is found that other functional molecules, such as heparin, can be incorporated into the PEMA matrix. The approach developed in this investigation is promising for the fabrication of coatings for biomedical implants and devices using natural surfactants and avoiding the use of toxic solvents. Such coatings can be deposited as laminates of different layers, functionalized with bioceramics, drugs, and various biomolecules. [ABSTRACT FROM AUTHOR]

This investigation is motivated by increasing interest in ferrimagnetic materials and composites, which exhibit electrical capacitance. It addresses the need for the development of magnetic materials with enhanced capacitive properties and low electrical resistance. γ-Fe2O3-multiwalled carbon nanotube (MWCNT) composites are developed by colloidal processing and studied for energy storage in negative electrodes of supercapacitors. High energy ball milling (HEBM) of ferrimagnetic γ-Fe2O3 nanoparticles results in enhanced capacitive properties. The effect of HEBM on particle morphology is analyzed. Gallocyanine is used as a co-dispersant for γ-Fe2O3 and MWCNTs. The polyaromatic structure and catechol ligand of gallocyanine facilitated its adsorption on γ-Fe2O3 and MWCNTs, respectively, and facilitated their electrostatic dispersion and mixing. The adsorption mechanisms are discussed. The highest capacitance of 1.53 F·cm−2 is achieved in 0.5 M Na2SO4 electrolyte for composites, containing γ-Fe2O3, which is high energy ball milled and co-dispersed with MWCNTs using gallocyanine. HEBM and colloidal processing strategies allow high capacitance at low electrical resistance, which facilitates efficient charge–discharge. Obtained composites are promising for fabrication of multifunctional devices based on mutual interaction of ferrimagnetic and capacitive properties. [ABSTRACT FROM AUTHOR]

This investigation addresses the challenges in the development of efficient nanostructured Mn3O4 cathodes for supercapacitors. A high areal capacitance and the ability to avoid a time-consuming activation procedure for electrodes with high active mass loading of 40 mg cm−2 are reported. This facilitates practical applications of Mn3O4 based electrodes. The highest capacitance of 6.11 F cm−2 (153 F g−1) is obtained from cyclic voltammetry at a scan rate of 2 mV s−1 and 6.07 F cm−2 (151.9 F g−1) from the chronopotentiometry at a current density of 3 mA cm−2 in a potential window of 0.9 V in a neutral Na2SO4 electrolyte. The new approach is based on the application of rhamnolipids (RL) as a capping agent for the synthesis of Mn3O4 particles and a co-dispersant for Mn3O4 and carbon nanotubes, which are used as conductive additives. The size and shape of the Mn3O4 particles are influenced by RL. The enhanced performance of the electrodes is linked to the chemical structure and properties of RL molecules, which exert influence on Mn3O4 particle size and shape during synthesis, reduce agglomeration, facilitate RL adsorption on Mn3O4 and carbon nanotubes, and influence their co-dispersion and mixing at the nanometric scale. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the need for the development of polymer coatings containing inorganic flame-retardant materials (FRMs) and the replacement of toxic halogenated FRMs. A green strategy is reported for the fabrication of poly(ethyl methacrylate) (PEMA)-FRM composite coatings using a dip-coating method. The use of water-isopropanol co-solvent allows the replacement of regular toxic solvents for PEMA. The abilities to form concentrated solutions of high-molecular-mass PEMA and to disperse FRM particles in such solutions are the main factors in the fabrication of coatings using a dip-coating technique. Huntite, halloysite, and hydrotalcite are used as advanced FRMs for the fabrication of PEMA-FRM coatings. FTIR, XRD, SEM, and TGA data are used for the analysis of the microstructure and composition of PEMA-FRM coatings. PEMA and PEMA-FRM coatings provide corrosion protection of stainless steel. The ability to form laminates with different layers using a dip-coating method facilitates the fabrication of composite coatings with enhanced properties. [ABSTRACT FROM AUTHOR]

The high theoretical capacitance of MnO2 renders it a promising material for the cathodes of asymmetric supercapacitors. The good dispersion of MnO2 and conductive additives in a nanocomposite electrode is a key factor for efficient electrode performance. This article describes, for the first time, the application of rhamnolipids (RL) as efficient natural biosurfactants for the fabrication of nanocomposite MnO2-carbon nanotube electrodes for supercapacitors. RL act as co-dispersants for MnO2 and carbon nanotubes and facilitate their efficient mixing, which allows for advanced capacitive properties at an active mass of 40 mg cm−2 in Na2SO4 electrolytes. The highest capacitance obtained from the cyclic voltammetry data at a scan rate of 2 mV s−1 is 8.10 F cm−2 (202.6 F g−1). The highest capacitance obtained from the galvanostatic charge–discharge data at a current density of 3 mA cm−2 is 8.65 F cm−2 (216.16 F g−1). The obtained capacitances are higher than the capacitances of MnO2-based electrodes of the same active mass reported in the literature. The approach developed in this investigation is simple compared to other techniques used for the fabrication of electrodes with high active mass. It offers advantages of using a biocompatible RL biosurfactant. [ABSTRACT FROM AUTHOR]

Metal oxide nanostructures are increasingly important materials for various emerging photocatalytic, photovoltaic and photoelectrochemical (PEC) applications. They are commonly used as photoelectrode materials due to their unique functional properties such as wide bandgap, reactive electronic transitions, and high stability. To increase the effectiveness of semiconductor metal oxides photoelectrodes, researchers seek to use various photoabsorption amplification and colloidal stability enhancement strategies. An effective method for achieving this is the surface functionalization of metal oxide semiconductors with catechol‐type ligands. Catechol‐type ligands are a family of organic molecules that adsorb very strongly onto metal oxides by forming complexes with metal atoms through adjacent phenolic —OH groups. Once adsorbed, catechol‐type ligands facilitate improved particle dispersion by inhibiting agglomeration and enhance photoexcitation in metal oxide semiconductors by improving visible light absorption. Herein, the surface complexation of catechol‐type ligand onto metal oxide semiconductor surfaces and their photoabsorption enhancement mechanisms is described. In addition, recent advances and trends in this area are described by presenting recent advancements made in applications of catechol‐modified metal oxide systems in photocatalysis, PEC biosensing, and solar cells. [ABSTRACT FROM AUTHOR]

This investigation describes for the first time the application of carbenoxolone for electrophoretic deposition (EPD) of different carbon materials, polytetrafluoroethylene (PTFE) and their composite films. Carbenoxolone is a versatile biosurfactant, which adsorbs on materials due to its amphiphilic structure and allows their charging and dispersion. Moreover, carbenoxolone exhibits film-forming properties, which are investigated in experiments on EPD of films using water and ethanol-water solvents. The new deposition process is monitored in situ and the deposition yield and film microstructure are analyzed at different conditions. The EPD mechanism of materials involves electrode reactions of the carbenoxolone surfactant. The data of potentiodynamic studies coupled with the results of impedance spectroscopy show that PTFE films can be applied to protect metals from corrosion. Electron microscopy, electrochemical techniques and modeling are used for analysis of the microstructure and porosity of films prepared at different conditions. Carbenoxolone is applied as a co-surfactant for the EPD of composites. [ABSTRACT FROM AUTHOR]

Applications of bile acids (BAs) and bile salts (BSs) in the nanotechnology of functional materials are described. The exceptionally strong solubilization and dispersion power of BAs/BSs is a key factor for the solubilization of dyes, drugs, and polymers for electronic, optical, and biomedical devices, fabrication of composites, based on carbon nanotubes, graphene, diamonds, quantum dots, and polymers for applications in energy storage devices, coatings for corrosion protection of metals, sensors and electronic devices. BAs/BSs have attracted attention for synthesis, design, and surface modification of advanced materials. BAs/BSs are used as reducing, capping, chelating and dispersing agents for the synthesis of nanoparticles of metals and alloys, and low temperature synthesis of stoichiometric nanostructured complex oxides. BAs/BSs exhibit unique self‐assembly properties, which are successfully used for the template synthesis of functional nanoparticles of controlled shapes. Particularly important are applications of BAs/BSs in the fabrication of dye sensitized solar cells with enhanced efficiency. Electrochemical strategies are discovered for the deposition of BA films and composites. Of particular interest are the unique gel‐forming properties of BAs/BSs, which provide a basis for the synthesis of nanoparticles of controlled size and fabrication of novel materials with advanced functionality. [ABSTRACT FROM AUTHOR]

This article describes for the first time the fabrication of an asymmetric device, which is based on negative Ti3C2Tx (MXene)–multiwalled carbon nanotube (MCNT) electrodes and positive polypyrrole (PPy) coated MCNT electrodes. The approach involves the feasibility studies of new strategies for achieving enhanced electrochemical performance of high active mass (AM) MXene electrodes. Good material performance at high AM of 35 mg cm−2 is linked to the application of multifunctional chelating dispersants for co-dispersion of Ti3C2Tx and MCNT and advanced water insoluble hydrophilic binders. The experimental results reveal the effect of the chemical structure of the dispersants and binders on electrode performance. Another important finding is the ability of achieving high capacitance of PPy-coated MCNT positive electrodes in a complementary potential range. The analysis of cyclic voltammetry data in Na2SO4 electrolyte for Ti3C2Tx–MCNT electrodes shows areal capacitance of 1.93 F cm−2 which is substantially higher than literature results for pure Ti3C2Tx and Ti3C2Tx composites. Moreover, high capacitance is obtained at much lower electrical resistance. Especially important is the possibility of achieving higher capacitance equal to 0.94 F cm−2 for the asymmetric supercapacitor in 0–1.6 V window, compared to literature data for symmetric supercapacitors with significantly lower capacitances in smaller voltage windows. [ABSTRACT FROM AUTHOR]

Pseudocapacitive materials are used for supercapacitor applications due to their exceptionally high capacitance and low cost. Good capacitive performance of the pseudocapacitive materials at high active mass loadings is vital for the development of the next generation of supercapacitor devices. This review describes recent advances in materials and nanotechnologies, which allows the development of advanced pseudocapacitive devices with high active mass. An important breakthrough is the discovery of novel dispersing and capping agents for the colloidal processing of nanoparticles. Particularly important are novel co‐dispersants that exhibit enhanced adsorption on materials of different types, such as inorganic nanoparticles, carbon nanotubes, and graphene. Conceptually new strategies are designed to fabricate coated particles. Recent innovations pave the way for the development of multifunctional redox‐active dopants‐dispersants and dopants‐oxidants to manufacture conductive polymer composites. Among the most important advances in nanotechnology is the development of template methods and heterocoagulation techniques for composite manufacturing. The progress in the design of novel surface modification techniques and materials, discovery of advanced anchoring groups, and development of liquid–liquid extraction allows agglomerate‐free processing of nanomaterials and composites. This review describes fundamental aspects of novel technologies and their applications in the manufacturing of pseudocapacitive devices for energy storage. [ABSTRACT FROM AUTHOR]

Many material manufacturing techniques require the use of nonaqueous colloidal suspensions, containing well dispersed oxide particles and various water insoluble functional components. We report an efficient method for the direct transfer of MnO2 and titania particles, synthesized in water, to an organic solvent through the interface of two immiscible liquids. Particle agglomeration during the drying stage was avoided, and stable suspensions of nonagglomerated particles in the organic phase were obtained. The benefits of this method were demonstrated by the fabrication of advanced composite MnO2-multiwalled carbon nanotube electrodes, containing a polymer binder, for electrochemical supercapacitors with high active mass loading and high active material to current collector mass ratio. The electrodes showed a capacitance of 5.13 F/cm2 and low impedance. High extraction efficiency from concentrated suspensions was achieved by the use of an advanced extractor, which allowed strong adsorption on the particles by the polydentate bonding. The extraction mechanism is discussed. [ABSTRACT FROM AUTHOR]

Poly(vinylbenzyl trimethyl ammonium chloride) (PVT) exhibits functional properties, which have generated interest in the fabrication of PVT and composite films. New electrochemical strategies have been utilized for the deposition of PVT-zirconia composites. The problems, related to the electrodeposition of strong polyelectrolytes, such as PVT, were addressed by the development of charge compensation mechanisms. The deposition strategies involved electrophoretic cathodic deposition (EPD) of PVT and EPD or electrochemical synthesis of zirconia. The proof of concept investigations involved deposition yield studies under different conditions, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and electron microscopy studies. The electrochemical strategies can be used for electrodeposition of various composites, utilizing the properties of functional polymers and inorganic materials. [ABSTRACT FROM PUBLISHER]

This paper reports the fabrication of an electrochemical supercapacitor (ES) with high gravimetric and areal capacitances, achieved at a high mass ratio of active material to current collector. The active material, polypyrrole, is in situ polymerized in an aerogel-based current collector composed of crosslinked cellulose nanocrystals (CNCs) and multiwalled carbon nanotubes (MWCNTs). Mechanical robustness, flexibility, and low impedance of the current collectors are achieved by the chemical crosslinking of CNC aerogels and efficient dispersion of MWCNTs through the use of bile acid as a dispersant. Furthermore, the advanced electrode design results in low contact resistance. A single-electrode areal capacitance of 2.1 F cm−2 is obtained at an active mass loading of 17.8 mg cm−2 and an active material to current collector mass ratio of 0.57. Large area ES electrodes and devices show flexibility, excellent compression stability at 80% compression, and electrochemical cyclic stability over 5000 cycles. Moreover, good retention of capacitive properties is achieved at high charge-discharge rates and during compression cycling. The results of this investigation pave the way for the fabrication of advanced lightweight ES, which can be used for energy storage in wearable electronic devices and other applications. [ABSTRACT FROM AUTHOR]