Pulsed laser-engineered single-atom Pt sites on MoC for unprecedented alkaline hydrogen evolution over acidic media

Abstract

In general, metal carbides are synthesized via high-temperature-programmed solid-gas reactions using methane under an inert atmosphere. However, fabricating single-atom (SA) catalysts on such carbide supports typically inherits these demanding conditions, requiring multiple chemical reagents and prolonged processing. To overcome these synthetic limitations, we introduced a pulsed laser-driven strategy that integrates pulsed laser ablation and liquid-phase irradiation to construct atomically dispersed Pt sites on molybdenum carbide (Pt/MoC) nanospheres with tunable loading densities. These catalysts exhibit improved hydrogen evolution reaction (HER) activity in alkaline media, despite HER conventionally favoring acidic conditions. To enhance the hydrogen production efficiency of the electrolyzer while reducing energy consumption, we strategically replaced the conventional oxygen evolution reaction with the hydrazine oxidation reaction (HzOR) at the anode. Strong metal-support interactions between Pt atoms and MoC modulate the local electronic structure, thereby optimizing the adsorption energies of key intermediates for HzOR. In situ Raman spectroelectrochemistry and theoretical calculations elucidate the reaction mechanism, highlighting the role of Pt SA sites in lowering activation barriers for N₂ and H₂ evolution. The optimized Pt/MoC catalyst achieves enhanced HER performance in overall hydrazine splitting compared with conventional overall water splitting, maintaining structural integrity and outstanding stability over 100 h at 30 mA cm⁻². This study establishes a pulsed laser-based strategy for atomic-engineered Pt/MoC as a promising platform for energy-effective and hydrazine-fueled hydrogen generation in alkaline conditions.