Stabilized hydroxide-mediated nickel-based electrocatalysts for high-current-density hydrogen evolution in alkaline media†
Large-scale production of green hydrogen by electrochemical water splitting is considered as a promising technology to address critical energy challenges caused by the extensive use of fossil fuels. Although nonprecious nickel-based catalysts work well at low current densities, they need large overpotentials at high current densities, which hinders their wide applications in practical industry. Here we report a hydroxide-mediated nickel-based electrocatalyst for high-current-density hydrogen evolution, which delivers a current density of 1000 mA cm−2 at an ultralow overpotential of 97 mV. Combined X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) results show charge redistribution of Ni sites caused by Mo and surface Fe, which can stabilize the surface nickel hydroxide at high current densities for promoting the water dissociation step. Combined in situ XAS, quasi in situ XPS, and density functional theory calculations indicate that Fe plays an important role in the improved catalytic activity. Such a catalyst is synthesized at the metre-size scale and delivers a current density of 500 mA cm−2 at 1.56 V in overall water splitting, demonstrating its potential for practical use. This work highlights a charge engineering strategy to design efficient catalysts for high current density electrochemical applications.