A MoNi₄(312) surface preferred reconstruction enhancing hydrogen evolution

Nickel-molybdenum (Ni-Mo) alloys have garnered significant attention for superior electrocatalytic hydrogen evolution reaction (HER). Generally, catalysts undergo reconstruction during HER, leading to surface structure evolution, which is crucial for catalytic properties. However, the real electroactive sites and mechanisms underlying the structure evolution of Ni-Mo alloys through the electrochemical process remain unclear. Herein, we propose a Ni-Mo alloy with enriched MoNi₄(312) plane exposure after electrochemical reconstruction due to its preferential growth during the HER. The atomic interaction within the MoNi₄(312) plane facilitates the electron transfer from Ni to Mo and optimizes the electronic configuration, accelerating the release of gaseous hydrogen and smoothing the HER process. The reconstructed Ni-Mo alloy demonstrates exceptional HER performance, achieving an ultrasmall overpotential of 23 mV at 10 mA cm^–2. Additionally, by scaling up the electrode by 8 times, the overpotentials required remain similar to a small electrode. This study provides insights into surface reconstruction and orientational crystal plane design of low-cost transition metal-based alloy catalysts for industrial hydrogen production. © 2024 Elsevier B.V.