FeCo@Fe@Pd nanocatalyst exhibits excellent selectivity towards the oxidation of EG and glycerol in ADAFCs.

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In this study, porous activated carbons (AC) were synthesized by an environmentally friendly technique involving chemical activation and carbonization, with an in-depth experimental study carried out to understand the electrochemical behaviour in different aqueous electrolytes (KOH, LiCl, and Na 2 SO 4 ). The electrochemical performance of the AC electrode was evaluated by different techniques such as cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The results obtained demonstrate that the AC materials in different electrolytes exhibit unique double layer properties. In particular, the AC electrode tested in 6 M KOH showed the best electrochemical performance in terms of specific capacitance and efficiency. A specific capacitance of 129 F g À1 was obtained at 0.5 A g À1 with a corresponding solution resistance of 0.66 U in an operating voltage window of 0.8 V, with an efficiency of $100% at different current densities.

We have fabricated a symmetric electrochemical capacitor with high energy and power densities based on a composite of graphene foam (GF) with ∼80 wt% of manganese oxide (MnO2) deposited by hydrothermal synthesis. Raman spectroscopy and X-ray diffraction measurements showed the presence of nanocrystalline MnO2 on the GF, while scanning and transmission electron microscopies showed needle-like manganese oxide coated and anchored onto the surface of graphene. Electrochemical measurements of the composite electrode gave a specific capacitance of 240 Fg−1 at a current density of 0.1 Ag−1 for symmetric supercapacitors using a two-electrode configuration. A maximum energy density of 8.3 Whkg−1 was obtained, with power density of 20 kWkg−1 and no capacitance loss after 1000 cycles. GF is an excellent support for pseudo-capacitive oxide materials such as MnO2, and the composite electrode provided a high energy density due to a combination of double-layer and redox capacitance mechanisms

Palladium based nano-alloys are well known for their unique electrocatalytic properties. In this work, a palladium-decorated FeCo@Fe/C core-shell nanocatalyst has been prepared by a new method called microwave-induced top-down nanostructuring and decoration (MITNAD). This simple, yet efficient technique, resulted in the generation of sub-10 nm sized FeCo@Fe@Pd nanocatalysts (mainly 3-5 nm) from a micron-sized (0.21-1.5 mm) FeCo@Fe/C. The electrocatalytic activities of the core-shell nanocatalysts were explored for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in alkaline medium. A negative shift of 300 mV in the onset potential for MOR was observed, with a current thrice that of the Pd/C catalysts. A very low resistance to electron transfer (R ct ) was observed while the ratio of forward-to-backward oxidation current (I f /I b ) was doubled. The overpotential of ORR was significantly reduced with a positive shift of about 250 mV and twice the reduction current density was observed in comparison with Pd/C nanocatalysts with the same mass loading. The kinetic parameters (in terms of the Tafel slope (b) = À59.7 mV dec À1 (Temkin isotherm) and high exchange current density ( j o ) = 1.26 Â 10 À2 mA cm À2) provide insights into the favorable electrocatalytic performance of the catalysts in ORR in alkaline media. Importantly, the core-shell nanocatalyst exhibited excellent resistance to possible methanol cross-over during ORR, which shows excellent promise for application in direct alkaline alcohol fuel cells (DAAFCs).

A green chemistry approach (Hydrothermal Microwave Irradiation) has been used to deposit manganese oxide on nickel foam-graphene. The 3D graphene was synthesized using nickel foam template by chemical vapour deposition (CVD) technique. Raman spectroscopy, X-ray diffraction (XRD), scanning electron and transmission electron microscopies (SEM and TEM); have been used to characterize structure and surface morphology of the composite respectively. The Raman spectroscopy measurements on the samples reveal that 3D graphene consists of mostly few layers with low defect density. The composite was tested in a three electrode configuration for electrochemical capacitor, and exhibited a specific capacitance of 305 F g -1 at a current density of 1 A g -1 and showed excellent cycling stability. The obtained results demonstrate that microwave irradiation technique could be a promising approach to synthesis graphene based functional materials for electrochemical applications.

A scalable production of high surface area nanoporous carbon material (~ 2994 m 2 g -1 ) with good distribution of micro-, meso-and macro-pores was hydrothermally synthesized using both cheap polymers and graphene foam as carbon sources. The as synthesised material shows a unique interconnected porous graphitic structure. The electrochemical double-layer capacitor fabricated from this nanoporous carbon material exhibited a superior supercapacitive performance of 188 F g -1 at current density 0.5 A g -1 . This corresponded to areal capacitance of 6.3 µF cm -2 coupled with a high energy of 0.56 µWh cm -2 (16.71 Wh kg -1 ) and a power density of 13.39 µW cm -2 (401 W kg -1 ) due to extended potential window of 1.6 V in KOH aqueous electrolyte. Moreover, no capacitance loss after 10,000 cycles was observed, owing to the 2 unique structure and large surface area of the active material. The outstanding performance of this material as supercapacitor electrode shows that it has great potential for high performance energy-related applications.

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