Symmetrical carbon/carbon double layer capacitors (EDLCs) were fabricated employing nanostructured mesoporous nongraphitized carbon black (NMCB) powders and their EDLC behavior was studied using electrochemical techniques viz., cyclic voltammetry, a.c.-impedance, and constant current cycling. Rectangular shape cyclic characteristics were observed indicating the double layer behavior of the NMCB carbon electrodes. The mechanism of double layer formation and frequency dependent capacitance were deduced from the ac-impedance analysis. Specific capacitance, power density and energy density were derived from constant current charge/discharge measurements. NMCB powders demonstrated a specific capacitance of about ∼39 F g −1 and the power density of 782 W kg −1 at a current density of 32 mA cm −2 . Nevertheless, at a low current density (3 mA cm −2 ), the specific capacitance of ∼44 F g −1 was achieved, which corroborates with the values obtained by means of ac-impedance (40 F g −1 ) and cyclic voltammetry (41.5 F g −1 ). The test cells demonstrated the stable cycle performance over several hundreds of cycles.

With every moving day, the aspect that is going to be the most important for modern science and technology is the means to supply sufficient energy for all the scientific applications. As the resource of fossil fuel is draining out fast, an alternative is always required to satisfy the needs of the future world. Limited resources also force to innovate something that can utilise the resource more efficiently. This work is based on a simple synthesis route of biomass derived hard carbon and to exploring the possibility of using it as electrochemical supercapacitors. A cheap, eco-friendly and easily synthesized carbon material is utilized as electrode for electrochemical energy-storage. Four different hard carbons were synthesized from KOH activated banana stem (KHC), phosphoric acid treated banana stem derived carbons (PHC), corn-cob derived hard carbon (CHC) and potato starch derived hard carbons (SHC) and tested as supercapacitor electrodes. KOH-activated hard carbon has provided 479.23 F/g specific capacitance as calculated from its cycle voltammograms. A detailed analysis is done to correlate the results obtained with the material property. Overall, this work provides an in depth analysis of the science behind the components of an electrochemical energy-storage system as well as why the different characterization techniques are required to assess the quality and reliability of the material for electrochemical supercapacitor applications.

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Hydrogen production using novel catalysts is regarded as one of the most needed technology for the future economic needs and water splitting to give H2 gas, which is a challenging task for large-scale production. This work reports the synthesis of Meso-Cu-BTC metal organic framework and further used for understanding its role in electrochemical hydrogen evolution reaction (HER) in 1 M NaOH solution. Meso-Cu-BTC electrocatalyst showed a less overpotential of 89.32 mV and an onset potential of 25 mV with an appreciable current density. Results show a low Tafel slope of 33.41 mVdec−1 and long-term durability. Thus, the overall results show that Meso-Cu-BTC acted as a good candidate for electrocatalysis towards hydrogen evolution.

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The present study reports the synthesis of a porous Fe-based MOF named MIL-100(Fe) by a modified hydrothermal method without the HF process. The synthesis gave a high surface area with the specific surface area calculated to be 2551 m 2 g –1 and a pore volume of 1.407 cm 3 g –1 with an average pore size of 1.103 nm. The synthesized electrocatalyst having a high surface area is demonstrated as an excellent electrocatalyst for the hydrogen evolution reaction investigated in both acidic and alkaline media. As desired, the electrochemical results showed low Tafel slopes (53.59 and 56.65 mV dec –1 ), high exchange current densities (76.44 and 72.75 mA cm –2 ), low overpotentials (148.29 and 150.57 mV), and long-term stability in both media, respectively. The high activity is ascribed to the large surface area of the synthesized Fe-based metal–organic framework with porous nature.

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