A non-noble, low cost, multicomponent electrocatalyst based on nickel oxide decorated AC nanosheets and PPy nanowires for the direct methanol oxidation reaction

The multicomponent electrocatalyst is a low-cost composite material exhibiting excellent catalytic activity suitable for methanol oxidation reactions (MOR). In this work, we report a glassy carbon electrode modified nickel oxide nanospheres (NiO) decorated biomass-derived activated carbon (AC) nanosheets and polypyrrole (PPy) nanowire, electrocatalyst (NiO_AC@PPy/GCE) for direct methanol oxidation fuel cell (DMFC) application. The SEM micrographs reveal the nanosheets and nanowire-like morphology of AC and PPy decorated with NiO nanospheres which provide a high surface area with electrocatalytic activity, and stability for MOR. The NiO_AC@PPy/GCE exhibits a high current density of 551 mA/mg at a low onset potential of 0.5 V (vs Ag|AgCl) towards electro-oxidation of 0.5 M methanol (MeOH) in an alkaline medium. This superior performance of the NiO_AC@PPy/GCE over other reported metal-oxides based electrocatalysts is attributed to the synergistic effect of the NiO_AC@PPy electrocatalyst, wherein NiO provides electrocatalytic active sites for MOR via Ni2+/Ni3+ redox couple while the PPy and AC contribute towards the chemical stability and electrical conductivity of the electrode, respectively. The electrode shows 79% of capacity retention after 10,000 s of chronoamperometry displaying excellent chemical stability with reduced effect of CO intermediate poisoning at the electrode surface. This excellent stability and overall performance of the NiO_AC@PPy proves it as an ideal, low-cost non-noble electrocatalyst for DMFCs.