Electrodeposited Ni[sbnd]Co[sbnd]P hierarchical nanostructure as a cost-effective and durable electrocatalyst with superior activity for bifunctional water splitting

Designing earth-abundant, cost-effective catalysts with superior performance for electrochemical water splitting is among the essential global challenges. In this study, amorphous Ni[sbnd]Co[sbnd]P coatings are applied on nickel nanocones array using the cyclic voltammetry electrodeposition method in different cycles and nickel-to-cobalt ratios. The electrocatalytic activities of the as-fabricated electrodes are studied for hydrogen evolution reaction and oxygen evolution reaction in alkaline and neutral solution. The three-dimensional nickel nanocones expose more active surface area for hydrogen evolution reaction and oxygen evolution reaction. Binder-free Ni[sbnd]Co[sbnd]P@nickel nanocones electrode exhibits superior hydrogen evolution reaction catalytic activity in the alkaline solution, which requires only 51 and 110 mV for delivering 10 and 100 mAcm⁻², respectively. Also, this electrode exhibits low oxygen evolution reaction overpotential of 221 mV and 254 mV at 10 and 100 mAcm⁻², respectively. The fabricated electrode is able to sustain the current density of 100 mAcm^-2 with negligible degradation in overpotential which shows remarkable electrochemical stability. Moreover, this active and stable bifunctional electrocatalyst is used for full water splitting, able to deliver the current density of 10 mAcm⁻² in 1.53 V. Also, the fabricated electrode represented favorable behaviors as electrocatalyst for both HER and OER in neutral solution.