Nickel–Molybdenum Nanoparticles Anchored on Molybdenum Oxide as High-Performance Electrocatalyst for Hydrogen Production in Alkaline Water Electrolysis

The development of efficient and cost-effective electrocatalysts for alkaline water electrolysis is crucial for advancing hydrogen production technologies. Herein, we report the synthesis and characterization of a highly active, platinum-group-metal-free electrocatalyst for the hydrogen evolution reaction in alkaline media. The catalyst is obtained via the exsolution of Ni-Mo alloy nanoparticles anchored on MoO₂ during the reduction of a NiMoO₄ precursor grown on porous nickel substrates. It demonstrates high catalytic activity, achieving benchmark performance with an overpotential of -89 mV and a cell voltage of 1.71 V at a current density of 1 A/cm². Electrochemical testing, including operation at high current densities under industrially relevant conditions (80 °C, 30 wt % KOH, flowing electrolyte), validates its suitability for large-scale applications. Importantly, structural analysis reveals the presence of Ni-rich Ni₁₀Mo particles on MoO₂ rather than the often-proposed Ni₄Mo alloy, providing insight into the actual active phase of Ni-Mo catalysts. This distinction advances the fundamental understanding of Ni-Mo chemistry and offers guidance for the rational design of high-performance, platinum-group-metal-free catalysts for hydrogen evolution.