Topological\nFormation of a Mo–Ni-Based Hollow\nStructure as a Highly Efficient Electrocatalyst for the Hydrogen Evolution\nReaction in Alkaline Solutions

Abstract

A Mo–Ni\nalloy has been demonstrated to be a benchmark noble-metal-free\ncatalyst for the hydrogen evolution reaction (HER) in alkaline solutions.\nNevertheless, further improvement on its catalytic activity is desired\nto meet industrial requirements. In this study, Mo–Ni-based\nhollow structures (MoNi-HS), backboned by MoO_3–<i>x</i> nanosheets and decorated with metallic MoNi₄ nanoparticles, were obtained via a topological transformation\nprocess by annealing MoNi-oxide hollow precursors in a reducing atmosphere.\nThis hollow structure allowed for a large proportion of catalytic\nsurface exposed in the electrolyte, leading to highly efficient utilization\nof active sites in the catalyst. As a result, robust catalytic activity\ntoward HER was recorded in 1 M KOH electrolyte: a low overpotential\nof 38 mV to deliver a current density of 10 mA/cm² and\na very small Tafel slope of 31.4 mV per dec. Such a remarkable performance\nof MoNi-HS even outperformed the catalytic activity of the commercial\nPt/C electrocatalyst, addressing an effective strategy to promote\nthe catalytic performance of noble-metal-free catalysts.