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The conversion of nitrogen to ammonia offers a sustainable and environmentally friendly approach for producing precursors for fertilizers and efficient energy carriers. Owing to the large energy density and significant gravimetric hydrogen content, NH

3D chitosan scaffolds treated with alkali showed enhanced mechanical properties and stability in aqueous conditions. Chitosan is a preferred polymer for biomedical applications due to its antimicrobial, antioxidant and wound healing properties. Chitosan has been made into films, fibers, micro and nanoparticles and electrospun membranes for tissue engineering, drug delivery and other medical applications. However, materials made from chitosan have poor strength and stability. Compared to other forms, 3D scaffolds are more suitable for tissue engineering and other applications but are relatively easily susceptible to moisture and have poor strength due to their porous structure. Several physical and chemical approaches have been used to increase the strength and stability of chitosan biomaterials. In this study, we demonstrate that a simple treatment with alkali will substantially improve the strength and stability of freeze-dried 3D chitosan scaffolds. Three different concentrations of chitosan were lyophilized and made into scaffolds with varying properties. These scaffolds were alkali treated and tested for their increase in strength, resistance to water and other properties. Up to 50% increase in strength was possible when higher concentrations of chitosan and alkali treatment were used. The scaffolds have good activity against both gram positive and gram negative bacteria with the highest percentage of inhibition being 97%. Scaffolds also showed the ability to generate hydroxyapatite when incubated in phosphate buffered saline (PBS) for 7 days. This study provides a novel approach to obtain 3D chitosan scaffolds with properties suitable for medical, food and other applications.

Metal/metal oxide nanocomposites (NCs) have been attracting significant attention in recent times because of their applications in the fields of energy and environment. In the present work, we investigate the photocatalytic and electrochemical performances of Ni/NiO NCs synthesized by a facile and cost-effective reduction method using lithium salt as the dopant. Lithium influences the size, morphology and structural constitution of the final product. A variation in the lithium percentage was seen to have a direct effect on the Ni content. The structural conformation of the samples has been analyzed by XRD and further confirmed by XPS. A low optical energy bandgap (∼3.7 eV) and a mesoporous structure of the as-prepared samples were seen to play a crucial role in achieving the photocatalytic degradation of the cationic organic dyes concomitant to its electrochemical activity. On illumination with UV light, the Li-doped Ni/NiO NCs demonstrated rapid degradation of crystal violet and methyl violet 2B dyes. The synergism arising due to the substitutional doping of lithium and the presence of metallic nickel leads to efficient photodegradation of the dye pollutants by the catalysts. Further, the Li-doped Ni/NiO NCs displayed a better electrochemical performance than the undoped samples. The NC with 1 wt% Li exhibited the best values of specific capacitance (276.2 F g−1 at 5 A g−1) with an excellent cycling ability (

A rapid and facile method for the detection of hydrogen peroxide (H2O2) in chemical reactions has been reported using molybdenum oxide Nanoparticles (MoO3 NPs) synthesized via an eco-friendly and economical solution combustion route using Centella Asiatica leaf powder. The formation of porous agglomerated NPs has been confirmed by subjecting the synthesized material to various analytical and spectroscopic techniques to understand their size, morphology, and nature. In this study, MoO3 NPs-based electrode has been fabricated and its electrochemical sensing capabilities have been investigated. Electrochemical investigation of hydrogen peroxide exhibits an increase in the peak current response at pH 13. The cyclic voltammetry (CV) results indicate an appreciable reversibility of the electrode reaction. The anodic and cathodic peaks show a greater inclination towards the positive and negative sides with a significant development in the reversibility of the oxidation and reduction states. These findings open up new avenues for the exploration of various other metal oxide based NPs as sensors for the detection of chemically toxic substances.

Textiles are known to be the best substrates for growing a variety of microorganisms efficiently at appropriate temperatures and humidity in contact with the human body. Currently, increasing public concern about hygiene has been driving many investigations about antimicrobial surface modification of textiles. The present research reports on the synthesis and characterization of nanosized copper oxide nanoparticles (CuONPs) and their application on cotton fabric to increase the bactericidal and hydrophobic properties. The synthesized materials have been subjected to spectroscopic and microscopic characterizations to help in understanding their structure, morphology, size, and composition. Further, upon dispersion of the nanoparticles onto the fabric, its hydrophobicity and mechanical properties were evaluated using electron microscopy and universal testing machine. Treated cotton fabric exhibits higher tensile strength (32 MPa) than the untreated one (27 MPa), whereas copper nanoparticle-coated cotton fabric shows a fair hydrophobicity. Moreover, CuONPs-treated and untreated cotton fabrics have been analyzed for bactericidal activity against various gram-negative and gram-positive strains. Finally, the CuONPs-coated cotton fabric displays greater antibacterial activity against E. coli and exhibits superior antimicrobial activity even after 30 cycles of washing, indicating that the CuONPs-coated cotton fabric has a higher potential to be employed as a medical textile to avoid cross-infection within a clinical environment.

A green combustion method using Aloe vera latex as a fuel was employed to synthesize nanocrystalline cupric oxide (CuO). The nanocrystalline nature and phase of CuO was confirmed by powder X-ray diffraction. Applying the Kubelka–Monk function to diffuse reflectance spectra showed the band gap of CuO to be 1.632 eV. Paracetamol and d -glucose in 1 M KOH solution were sensed using a carbon paste electrode modified using CuO nanoparticles (NPs). The cyclic voltammetry results suggest that CuO NPs possess superior electrochemical properties due to a lower value of the difference between oxidation and reduction potential (EO-ER). The proton diffusion coefficient for CuO electrode material was1.5047 × 10−5cm2s−1. Electrochemical impedance and Bode studies confirmed that the charge-transfer resistance value of CuO NPs was on the lower side due to the phase angle (55°) being near to ф = ᴨ/2. The electrochemical behavior indicates that CuO is a promising electrode material for sensing molecules such as paracetamol and glucose.

The present study confirms the application of phytochemicals of Lemon rind (LR) towards the synthesis of activated carbon using a low temperature carbonization method. The structural, morphological, and electrochemical properties of the prepared carbonized flakes epoxy (CFE) electrode has been analyzed using various characterization techniques. The electrochemical double layer capacitance (EDLC) behavior of the LR-activated carbon has been evaluated. The synthesized LR-activated carbon material exhibited flake like structure along with hydroxyl groups as confirmed by studies by scanning electron microscope (SEM), X-ray diffractometer (XRD), and Fourier transform infrared (FTIR) spectroscope. In addition, the band gap energy (Eg) has been estimated using diffused reflectance spectroscopy (DRS-UV-Vis) and found to be 2.06 eV. The electrochemical property of CFE-electrode was studied utilizing cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) techniques. The galvanostatic charge–discharge tests for this prepared carbon flake electrode demonstrated excellent capacitance performance, making it favorable for the fabrication of supercapacitors. These progressive results could be considered for the enlargement of novel assets to scale for power-storage utility using low-cost carbon materials in various energy storage applications as well.

The current energy situation requires not only enormous energy in a brief period of time but clean energy as well. In this direction, a dye-sensitized solar cell (DSSC)—supercapacitor (SC) integrated energy device has been fabricated. This embedded energy system has a specific advantage such as easy manufacturing, low manufacturing costs, and flexible substrates compatibility. A natural photosensitizer was extracted from readily available beetroots and characterized using ultraviolet (UV)-visible spectroscopy. The zinc oxide semiconductor was synthesized using microwave technique and regarded as the DSSC photoanode material. The ZnO’s phase, purity, and morphology were investigated using X-ray diffraction (XRD) spectroscopy and scanning electron microscope. The iodine-doped cellulose acetate propionate (CAP) biopolymer electrolyte functions as the DSSC and supercapacitor electrolyte. The solid polymer electrolyte conductivity and dielectric studies were performed using electrochemical impedance spectroscopy (EIS). The laser-induced technique was used to synthesize graphene that plays a dual purpose as photocathode in DSSC and supercapacitor electrodes. The embedded energy unit from the DSSC-supercapacitor demonstrates a 6.75% fill factor representing its decent efficiency.

The persistence of hollow centre in the carbon obtained from milkweed floss provides exceptional sorption characteristics, not seen in common biomasses or their derivatives. A considerably high sorption of 320mg of lead per gram of milkweed carbon was achieved without any chemical modification to the biomass. In this research, we have carbonized milkweed floss and used the carbon as a sorbent for lead in waste water. A high surface area of 170m2g-1 and pore volume of 1.07cm3g-1 was seen in the carbon. Almost complete removal (>99% efficiency) of lead could be achieved within 5min when the concentration of lead in the solution was 100ppm, close to that prevailing in industrial waste water. SEM images showed that the carbon was hollow and confocal images confirmed that the sorbate could penetrate inside the hollow tube.

Nanostructured NiO and Li-ion doped NiO have been synthesized via a facile microwave technique and simulated using the first principle method. The effects of microwaves on the morphology of the nanostructures have been studied by Field Emission Spectroscopy. X-ray diffraction studies confirm the nanosize of the particles and favoured orientations along the (111), (200) and (220) planes revealing the cubic structure. The optical band gap decreases from 3.3 eV (pure NiO) to 3.17 eV (NiO doped with 1% Li). Further, computational simulations have been performed to understand the optical behaviour of the synthesized nanoparticles. The optical properties of the doped materials exhibit violet, blue and green emissions, as evaluated using photoluminescence (PL) spectroscopy. In the presence of Li-ions, NiO nanoparticles exhibit enhanced electrical capacities and better cyclability. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results show that with 1% Li as dopant, there is a marked improvement in the reversibility and the conductance value of NiO. The results are encouraging as the synthesized nanoparticles stand a better chance of being used as an active material for electrochromic, electro-optic and supercapacitor applications.

In this paper, the performance of Fe based redox flow batteries (IRFBs) was dramatically improved by coating N-doped carbon spheres (NDCS) on the graphite felt electrodes. NDCS was synthesized by the single-step hydrothermal method using dextrose and ammonia as a precursor and coated over a graphite felt electrode by electrostatic spraying. The weight of NDCS required for the modification of the electrode to achieve the effective performance of the battery was studied using electrochemical techniques. Cyclic voltammetry (CV) and potentiodynamic polarization study was used to evaluate the kinetic reversibility and linear polarization resistance offered by the electrode towards electrolyte. The characterizing features of the NDCS, untreated graphite felt (UGF) electrode, and optimized modified graphite felt (MGF) electrode were analyzed using SEM, EDAX, XRD, and Raman spectroscopy. The charge-discharge studies were performed for the 132 cm2 IRFB using a 2 mg/cm2 MGF electrode as a positive electrode by varying the current densities from 20 to 60 mA/cm2. The cell resulted in an average coulombic efficiency (CE) of 93%, voltaic efficiency (VE) of 72%, and energy efficiency (EE) of 68% for 15 cycles at the current density of 30 mA/cm2. The improvement in the performance of the IRFB is due to the presence of electrochemically active nitrogen-bearing carbon catalysts. In this paper, the pioneering effort has been made to improve the efficiency of the IRFB with an active area of 132 cm2 using glycine as the ligand.

By employing a simple hydrothermal process, a new class of ternary alkali metal-based chalcogenide (NaFeS2 (NFS)) has been produced and anchored on to reduced graphene oxide (rGO) sheets for the first time. Transition metal-based chalcogenides (TMC) exhibit limited conductivity because of their semiconducting nature and hence, engineering TMCs with 2D carbonaceous materials yields better catalytic performance. Alkali metal-based chalcogenides and their composites appear to be promising alternatives, whose electrochemical properties haven't been explored much. This work presents a detailed insight into the structure and morphology of the prepared NFS-rGO composite, along with its electrochemical properties. The cyclic voltammetry (CV) response at the NFS-rGO composite electrode for the redox probe K4Fe(CN)6 is better with low peak to peak separation potentials (ΔEp ​= ​99 ​mV) compared to the individual components NFS (ΔEp ​= ​190 ​mV) and GO ( ∆ E p ​= ​130 ​mV), indicating a better electron transfer kinetics. The NFS-rGO composite electrode displays an enhanced electrocatalytic activity as evidenced by the high electrochemically active surface area (6.09 ​× ​10−2 ​cm2) and the heterogeneous electron transfer rate constant (k0 ​= ​5.4 ​× ​10−2 ​cms−1). In general, the NFS-rGO composite exhibits excellent material as well electrocatalytic properties due to the synergistic effect between NFS and rGO and can further be explored for electrochemical sensing applications as well.

For large-scale energy storage, iron-based flow batteries (IRFBs) have been considered as a better choice because of their low-cost and use of environmentally friendly iron-based salts. The development of a IRFBs has been limited by the sluggish kinetics of the reaction, especially at the positive electrode during charging. Therefore, it is very important to look for stable electrolytes and superior electrode materials along with their modifications. Carbon-based electrodes are majorly used in IRFBs and these electrodes are feasible to modify using electrocatalysts. In the current study, nitrogen-doped carbon particles (NICaps) derived from Bermuda grass were used to modify graphite felt electrode. SEM, EDAX, Raman, and XPS analysis were used to characterize the modified graphite felt (MGF) electrode. It was observed that the NICaps MGF electrode had a significant improvement in electrochemical properties. The cathodic and anodic peak currents for the MGF electrode (1.55 and 1.63 mA/cm2 respectively) had a remarkable increase in comparison with the untreated graphite felt electrode (UGF) (0.48 and 0.88 mA/cm2 respectively). The Nyquist plot and the data derived from the equivalent circuit indicated lower charge transfer resistance for MGF. The charge-discharge studies carried out using 132 cm2 cell reveals that the modified electrodes result in higher current uptake of 50 mA/cm2 whereas the current uptake from the UGF electrode was limited to 20 mA/cm2. The battery resulted in an average coulombic efficiency of 95%, the peak power density of 60 mW/cm2, and better stability during multiple cycling.

Polyethylene tetraphthalate (PET) bottles, a major environmental pollutant from the food industry, has been used as an activated carbon source in the current work. The specific surface area of the activated carbon has been analyzed using N2 adsorption/desorption isotherms, at different sonication time periods. A high surface area of 899 m2 g-1 with microporosity has been achieved for 20 h sonication followed by activation at 800 °C. To further enhance the material performance, carbon doped MoS2 (MoS2–C), using conventional hydrothermal technique has been synthesized. Different composite ratios of activated carbon and MoS2-C have been tested using electrochemical impedance spectroscopy and the best ratio owing to lesser charge-transfer resistance has been chosen for supercapacitor and HER analysis. The porous network of the plastic derived activated carbon (PAC) with a few layers of MoS2–C contributes significantly to the increase in the power density (469 W kg-1). By inducing defects on the material surface, there has been a significant enhancement in the electrocatalytic activity on PAC and this facilitates HER on its surface. Subsequently, the HER activity of the PDAC/MoS2–C composite has also been reported. Here, the PDAC defective sites along with the hexagonal MoS2–C’s largely exposed reactive edges indicate a reduction in the overpotential and Tafel values of −195 mV and −82 mVdec−1, suggesting that the material under investigation is a good catalyst for electrochemical HER. Also, this article reports for the first-time, HER activity of defect induced plastic derived activated carbon and its excellent catalytic activity.

A new photocatalytic material sodium iron disulfide (NaFeS2) has been synthesized via a hydrothermal method for the degradation of methylene blue (MB) and indigo carmine (IC). This material has been subjected to various analytical, electrochemical and photocatalytic studies to understand its morphology, crystallinity, band gap, oxidation-reduction potential and ability to catalyse the rate of dye degradation. The material exists as nanorods with a thickness of 30–100 nm and a monoclinic phase with an average crystallite size of 25–30 nm. The energy bandgap of the prepared photocatalyst has been calculated using the Kubelka-Munk function and is found to be 2.01 eV. Using a UV light source, the photocatalytic activity of NaFeS2 has been carried out, where the time of irradiation determined the ability of the catalyst to degrade the dye under investigation. With a degradation efficiency of 97% in 105 min for MB and 99% in 45 min for IC, NaFeS2 appears as an excellent photocatalytic material. The electrochemical studies also act as a testament for NaFeS2’sadmirable photocatalytic property. The photocatalytic and electrochemical activities of NaFeS2 offer an innovative platform for the treatment of various other environmental pollutants as well.

A successful attempt has been made to synthesize nanostructured cobalt oxides at different weight percentage of lithium ions via rapid and facile microwave combustion method. The dopant has a high influence on Co3O4 nanostructure which has been well-studied by various spectroscopic and microscopic analytical tools such as Fourier Transform Infrared Spectroscopy (FT-IR), Powder X-ray Diffractometry (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The synthesized nanostructures exhibit an optical band gap in the range of 3.099-3.211 eV. Cyclic voltammetry studies indicate that doping Li into nanostructured cobalt oxide increases the peak currents of oxidation and reduction peaks, thereby reducing the potential (EO-ER) between the peaks. Amongst the samples studied, 1 wt.% Li doped cobalt oxide has shown the best surface electrochemical activity. The sample reported a decrease in charge transfer resistance with a simultaneous increase in its capacitance. At the same time, the synthesized samples also manifest appreciative photocatalytic activity. The doped samples exhibit selective photocatalytic degradation of CV and MV2B dyes which are cationic in nature; the degradation of anionic dye ARS could not be achieved. Nevertheless, these nanostructured materials offer encouraging electrochemical results coupled with photocatalytic applications paving new dimensions for future research in this direction.

The formation of Fe3O4 nanoparticles by hydrothermal process has been studied. X-ray Diffraction measurements were carried out to distinguish between the phases formed during the synthesis. Using the synthesized Fe3O4 nanoparticles, poly(vinyledene fluoride)-Fe3O4 composite films were prepared by spin coating method. Scanning electron microscopy of the composite films showed the presence of Fe3O4 nanoparticles in the form of aggregates on the surface and inside of the porous polymer matrix. Differential Scanning calorimetry revealed that the crystallinity of PVDF decreased with the addition of Fe3O4. The conductitivity of the composite films was strongly influenced by the Fe3O4 content; conductivity increased with increase in Fe3O4 content. Vibration sample magnetometry results revealed the ferromagnetic behavior of the synthesized iron oxide nanoparticles with a Ms value of 74.50 emu/g. Also the presence of Fe3O4 nanoparticles rendered the composite films magnetic. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The study of electrochemical behavior of organic–inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 × 10−2 S cm−1 is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol−1.