3D volcanic-rock-like structure of Co-doped Ni/MoNi4 heterostructure with corallite pattern surface as bifunctional electrocatalysts for urea-assisted water splitting

Abstract

The key to the design of energy-efficient hydrogen production system lies in the development of highly catalytic, low-cost and non-precious metal catalysts. Meanwhile, the replacement of great-energy-consuming oxygen evolution through the reactions involving small molecules is easily oxidizable at the anode. Herein, we report the multicomponent intermetallic of Co-doped Ni/MoNi₄ (Co-Ni/MoNi₄) heterostructure, which is directly integrated on conductive nickel foam as an urea-assisted water splitting electrocatalyst. The Co-Ni/MoNi₄ product possesses 3D volcanic-rock-like architecture with multideck and scabrous corallite pattern surface, which presents satisfactory electrocatalysis in water splitting territory. It demonstrates a low overpotential of 46.8 mV to achieve the current density of 10 mA cm⁻² for hydrogen evolution reaction (HER), and showcases a potential of 1.33 V for urea oxidation reaction (UOR) at 10 mA cm⁻². The Tafel slopes of HER and UOR for Co-Ni/MoNi₄ are 72.2 and 29.1 mV dec⁻¹, respectively. What's more, the Co-Ni/MoNi₄ couple electrolyzer only requires a cell voltage of 1.40 V to attain 10 mA cm⁻² and exhibits good stability for urea electrolysis.