Hydrogen Migration Mechanism: Hydrogen Spillover Effect Enables Enhanced Hydrogen Evolution Reaction on MoC@MoN Heterostructure in a Wide pH Range

It remains critical and challenging to synthesize non-noble metal catalysts with excellent hydrogen evolution reaction (HER) activity in a wide pH range. High-temperature pyrolysis is one of the main methods for catalyst synthesis but can be time-consuming and leads to agglomeration easily. In view of this, molybdenum carbide and molybdenum nitride composite (MoC@MoN) was prepared via CO₂ laser irradiation technology. The catalytic activity of the as-prepared catalysts can be effectively regulated by controlling the usage of Na₂MoO₄·2H₂O and the applied CO₂ laser power. In acidic and alkaline media, the as-prepared MoC@MoN requires an overpotential of only 63 mV and 34 mV, respectively, at a current density of 10 mA cm^-2 and exhibits considerable electrochemical and structural durability, making it a suitable candidate for hydrogen production in a wide pH range. Theoretical calculations reveal the surface adsorption and desorption properties of reactive hydrogen and confirm the energetically favorable hydrogen spillover on the heterostructured MoC@MoN interface. The construction of the heterostructured interface enhances the activation of H₂O* and further decreases the energy barrier of H₂O* dissociation, thereby promoting the Volmer step and the H* supply for HER on the MoC@MoN interface. The integration of efficient H* adsorption on MoN and easy desorption on MoC effectively accelerates the Tafel step and hydrogen spillover, resulting in excellent HER performance of MoC@MoN. The strategy presented in this paper may offer a unique and viable approach for designing and synthesizing high-performance, low-cost HER catalysts, applied in a wide pH range.