Substrate Dependent Electrodeposition of Ni-Co Alloy for Efficient Hydrogen Evolution Reaction

Nickel-cobalt alloys are electrodeposited on different substrates (copper, stainless steel and mild steel) adopting cyclic voltammetry approach. Structural studies confirm the formation of face-centred cubic phases of Ni-Co alloy on all three substrates. Different morphologies of Ni-Co such as spheres and aggregated particles are observed when deposited on different substrates. The anodic and cathodic peaks of Ni-Co alloys are observed at 0.15, 0.3 V, 1.2 V and 1.3 V (vs. RHE) in case of all the three substrates. Overpotential for Ni-Co electrodeposited on Cu (Ni-Co/Cu) is the lowest eta = -131 mV (vs. RHE) at 10 mA/cm(2) compared to other two electrodes due to the porous morphology and higher electroactive surface area than the other electrodes. Tafel slope of Ni-Co/Cu (-193 mV/dec) is found to be lowest, among all three electrodes. The stability analysis of 12 h reveals that the Ni-Co/Cu is most stable compared to other electrodes. Hence, Ni-Co alloys deposited on copper substrate can be a suitable choice for electrochemical hydrogen generation by water splitting.