Engineering MoC/Mo2C heterojunction to reconstruct metastable MoC (200) plane for enhanced alkaline hydrogen evolution

The development of high-performance non-precious metal-based heterostructures is of great significance for advancing large-scale commercial water electrolysis. Herein, we demonstrate a temperature-induced phase transition strategy of tuning MoC to Mo 2 C to synthesize MoC/Mo 2 C heterojunctions supported on nitrogen-doped carbon spheres, denoted as MoC/Mo 2 C@NC, for efficient alkaline hydrogen evolution (HER). The intrinsic HER mechanism of the catalyst was analyzed by both comprehensive characterization and density functional theoretical calculations. It is found that the construction of the MoC/Mo 2 C heterojunction stabilizes the originally unstable MoC (200) plane, converting it to a metastable state, thereby greatly lowering the reaction energy barrier of the catalyst. The nitrogen-doped carbon substrate not only enhances the dispersion and structural stability but also promotes electron transfer. Moreover, the flower-like architecture provides abundant active sites and facilitates hydrogen desorption kinetics. Benefiting from these synergistic effects, the optimized MoC/Mo 2 C@NC catalyst delivers excellent electrocatalytic performance, achieving a low overpotential (η 10  = 101 mV), which surpasses most reported non-precious metal-based catalysts in alkaline environment.