Plasma-assisted synthesis of hierarchical NiCoxPy nanosheets as robust and stable electrocatalyst for hydrogen evolution reaction in both acidic and alkaline media

Abstract

Transition metal phosphides are emerging non-noble metal electrocatalysts for hydrogen evolution reaction (HER) in water splitting. Herein, porous nickel cobalt phosphide nanosheet arrays with hierarchical structure were synthesized on carbon cloth (NiCoxPy-P/CC) as a robust and stable HER electrocatalyst by a facile approach involving electrodeposition and an effective PH3 plasma-assisted phosphorization. Owing to the unique structure with porous nanosheets composed of defect-abundant fine nanocrystals, the as-synthesized NiCoxPy/CC electrocatalyst demonstrates superior catalytic activity for HER to its thermally-phosphorized counterpart. Only at the overpotential as low as 70 (in 0.5 M H2SO4) and 42 mV (in 1 M KOH), the current density of 10 mA/cm2 is achieved for the NiCoxPy/CC, which is among the best reported values for metal phosphide electrocatalysts. Moreover, the catalyst shows satisfying long-term durability up to 24 h in both the acidic and alkaline media. The outstanding HER performance and efficient synthesis strategy for the NiCoxP-P/CC makes it a promising electrocatalyst for hydrogen production.