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The current era focuses not only on producing solar energy but also preserving it for future use. Dye-sensitized solar cells (DSSC) and supercapacitors (SC) are such energy-based devices. DSSCs capture the solar energy and SCs store this captured energy. A natural anthocyanin dye extracted from Garcinia indica (kokum fruit) was used in the DSSCs. SnO2, one of the promising electrode materials for DSSC, was synthesized via a microwave technique. Blend polymer electrolytes (BPE) were prepared through a solution casting technique. A polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) blend with varying concentrations of potassium iodide, along with iodine dopant, was prepared as a BPE electrolyte composition. The best of the PVA-PVP/KI composition was chosen using Nyquist plots of electrochemical impedance spectroscopy (EIS). Varying the temperature, the dielectric and conductivity study of the chosen composition was studied in detail. A fast/single-step synthesis technique, namely a laser-engraved approach, was used for few-layer graphene synthesis. This graphene serves as a common platform for the DSSC-SC integrated device: as a counter electrode in DSSC and graphene-graphene symmetric electrode in SC. A DSSC-SC integrated device was fabricated and characterized using various analytical and microscopy techniques. The integrated device showed a 0.42 fill factor and 0.56% efficiency. The discharge time for integrated DSSC-SC cells was found to be increased threefold. [ABSTRACT FROM AUTHOR]

MoO3 nanorods were synthesized through the microwave method and the nanocomposites of MoO3/activated carbon were prepared for supercapacitor and hydrogen evolution reaction (HER). The XRD pattern revealed that the prepared MoO3 has a hexagonal phase (h-MoO3). The as-prepared h-MoO3 was composited with activated carbon (AC) and tested for supercapacitor studies. The fabricated supercapacitor exhibited an appreciable specific capacitance, power density, and energy densities. Further, dedoping of nitrogen in the doped AC creates defects on AC (DAC). These DAC/MoO3 nanocomposites were prepared and tested for its electrocatalytic activity towards hydrogen evolution reactions. DAC/MoO3 nanocomposite showed much higher electrocatalytic activity than the neat MoO3.Microwave synthesized h-MoO3 and active/defective activated carbon composites for supercapacitor and hydrogen evolution reactions [ABSTRACT FROM AUTHOR]

Low-cost, earth-abundant, clean and high stability material are of undivided interest for energy storage and conversion. The present work involves the investigation of one such material, activated carbon (AC), that is derived from abundantly available biomass – Tendu leaves. The work also addresses hydrothermal synthesis of 2-D MoS 2 layers and composites with AC, for supercapacitors and hydrogen evolution reaction (HER). AC derived from Tendu leaves showed micro and mesopore structure with high specific surface area (SSA) of 1509 m 2  g −1 . Layered MoS 2 nanosheets sheets, showed a biphasic system namely, 1-T and 2-H. Different ratios of AC and MoS 2 nanocomposites are prepared. And the best ratio composites tested for symmetric and hybrid supercapacitor electrodes and HER. Symmetric supercapacitor and hybrid supercapacitors exhibited good cycle stability and show higher specific capacitance of 261 F g −1 and 193 F g −1 respectively, at a scan rate of 2 mV s −1 . Defective sites were created on AC for electrochemical HER. The defects were created through, hydrothermal N doping followed by high-temperature dedoping of the N-doped AC. The defective activated carbon (DAC) showed a reduction in SSA of 1300 m 2  g −1 . The nanocomposites of DAC/MoS 2 were then tested for HER. The nanocomposites exhibited enhanced catalytic activity owing to better hydrogen evolution with lesser Tafel slope of −84 mVdec −1 . [ABSTRACT FROM AUTHOR]

Activated carbon is prepared from coconut shell by heating it around 500 °C for 2 h in a muffle furnace. This method is one of the easiest and most economical methods for the synthesis of Activated carbon. The dried coconut shell is carbonized and it is treated with KOH in the ratio of 1:3 carbon-activating agent (KOH) and the resulting slurry is dried in an oven at 60 °C for overnight. The dried mass is further activated at 450 °C then it is washed with an acid solution to remove KOH. The surface area of the synthesized activated carbon can be obtained by using nitrogen absorption-desorption experiment. Conducting polymer such as polyaniline prepared by oxidative polymerization of the respective monomer in tetrafluoroboric acid solution using potassium persulphate as an oxidant. The structure and doping of polyaniline were studied by FTIR, UV and Cyclic voltammetry studies. The conducting polymer is mixed with AC and prepared composites were characterized by UV, FTIR, and CV. The specific capacitance of composites calculated from charge-discharge at 0.5 mA g was found to be 99.6 Fg and for cyclic voltammetry, at the scan rate of 2 mV s, it is 77 Fg. [ABSTRACT FROM AUTHOR]

Proton and lithium-ion conducting biodegradable solid polymer electrolytes were prepared using blends of poly(styrene sulphonic acid) (PSSA) and starch for supercapacitor applications. The ionic conductivities have been calculated using the bulk impedance obtained through impedance spectroscopy with varying blend ratio and plasticizer. Glycerol as plasticizer improved the film formation property, while lithium perchlorate (LiClO) as dopant enhanced the conductivity. The maximum conductivity has been found to be 5.7 × 10 Scm at room temperature for 80/20 (PSSA/starch) blend ratio. The dielectric studies showed relaxation peaks indicating proton and Li conduction in the plasticized polymer blend matrix and dielectric modulus also exhibited a long tail feature indicating good capacitance. Differential scanning calorimetry thermograms showed two peaks and decreased with varying blend ratio and plasticizer. A carbon-carbon supercapacitor was fabricated using suitable electrolyte, and its electrochemical characteristics using cyclic voltammetry, AC impedance and galvanostatic charge-discharge were studied. Supercapacitor showed a fairly good specific capacitance of 115 Fg at 10 mV s. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical properties of a supercapacitor based on nanocomposite electrodes of activated carbon with TiO2 nano particles synthesized by a microwave method have been determined. The TiO2/activated carbon nanocomposite electrode with a composition of 1:3 showed a specific capacitance 92Fg−1. The specific capacitance of the electrode decreased with increase in titanium dioxide content. The p/p symmetrical supercapacitor fabricated with TiO2/activated carbon composite electrodes showed a specific capacitance of 122Fg−1. The electrochemical behavior of the neat TiO2 nanoparticles has also been studied for comparison purpose. The galvanostatic charge–discharge test of the fabricated supercapacitor showed that the device has good coulombic efficiency and cycle life. The specific capacitance of the supercapacitor was stable up to 5000 cycles at current densities of 2, 4, 6 and 7mAcm−2. [Copyright &y& Elsevier]

Abstract: Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and starch, plasticized with glycerol, as host polymer and lithium perchlorate (LiClO4) as a dopant is prepared by solution casting technique. The variation of conductivity has been investigated as a function of polymer blend ratio, plasticizer content, and LiClO4 concentration at temperature range of 298–343K using electrochemical impedance spectroscopy. The maximum conductivity is found to be 3.7×10−4 Scm−1 at room temperature for 60:40 (CS/starch) concentration. The dielectric properties of the electrolyte film exhibit a long tail feature indicating good capacitance. The activation energy of all samples is evaluated using the Arrhenius plot and it is found to be 0.52–0.75eV. The DSC thermogram peaks for CS-starch blends decreases with increase in the LiClO4 content. A carbon–carbon supercapacitor is fabricated using suitable blend electrolyte ratio and its electrochemical characteristics are discussed at various temperatures and current density. This supercapacitor shows a fairly good specific capacitance of 133Fg−1. [Copyright &y& Elsevier]

Abstract: A symmetrical (p/p) supercapacitor has been fabricated by making use of nanostructured zinc oxide (ZnO)–activated carbon (AC) composite electrodes for the first time. The composites have been characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD). Electrochemical properties of the prepared nanocomposite electrodes and the supercapacitor have been studied using cyclic voltammetry (CV) and AC impedance spectroscopy in 0.1M Na2SO4 as electrolyte. The ZnO–AC nanocomposite electrode showed a specific capacitance of 160F/g for 1:1 composition. The specific capacitance of the electrodes decreased with increase in zinc oxide content. Galvanostatic charge-discharge measurements have been done at various current densities, namely 2, 4, 6 and 7mA/cm2. It has been found that the cells have excellent electrochemical reversibility and capacitive characteristics in 0.1M Na2SO4 electrolyte. It has also been observed that the specific capacitance is constant up to 500 cycles at all current densities. [Copyright &y& Elsevier]

[Display omitted] • Ni(OH) 2 was annealed at 300, 400, 500, 600, 700, and 800 °C to obtain six NiO samples. • NiO-400 exhibits the highest BET surface area (∼82.8 m2/g) and porosity (∼47.8%) • Optimum morphology of NiO-400 resulted in the highest C a of 19.54 mF/cm2. • Asymmetric supercapacitor was screen printed with NiO-400 cathode and graphene anode. • This asymmetric supercapacitor achieved C a = 26.42 mF/cm2 and capacity = 10.9 mAh/g. We report the effects of thermal annealing on screen-printed NiO electrodes for asymmetric battery-type supercapacitors on flexible substrates. Ni(OH) 2 was synthesized and annealed at 300 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C to obtain six morphologically diverse NiO samples. FE-SEM, XRD, BET, and four-probe measurements were used to investigate their morphology, crystallinity, surface area, and conductivity, respectively. Six symmetric supercapacitors were screen-printed on a PET substrate with 1 M H 2 SO 4 electrolyte to probe their electrochemical properties. NiO annealed at 400 °C (NiO-400) demonstrated the highest areal capacitance of 19.54 mF/cm2 coupled with reduced charge-transfer resistance, consistent with the highly porous yet continuous structure observed via FE-SEM and BET surface analysis. With this, an inter-digital asymmetric supercapacitor with NiO-400 cathode and graphene anode was fabricated to demonstrate high areal capacitance of 26.42 mF/cm2, a wide potential window of 1.5 V (at 97.3% coulombic efficiency) and excellent flexibility with 96.4% retention (180°) after 1000 cycles. [ABSTRACT FROM AUTHOR]