Dual-phased Mo 2 C/Mo 3 N 2 /C nanosheets for efficient electrocatalytic hydrogen evolution

Mo 2 C is a promising electrocatalyst for hydrogen evolution reaction (HER) on account of its Pt-like electronic features. However, the electronic structure of pure Mo 2 C is unfavourable for the desorption of H ads ; thus, Mo 2 C exhibits poor catalytic performance. Herein, dual-phased Mo 2 C/Mo 3 N 2 /C nanosheets with an abundant heterostructure is prepared as a high-performance and low-cost electrocatalyst for HER. Mo 2 C/Mo 3 N 2 /C has low overpotentials of 76 and 121 mV at a current density of 10 mA cm −2 , with low Tafel slopes of 52.6 and 59.4 mV dec −1 , respectively, under alkaline and acidic conditions. Also, Mo 2 C/Mo 3 N 2 /C shows outstanding long-term stability with negligible decay in 1 M KOH and in 0.5 M H 2 SO 4 observed even after 3000 cycles. The excellent electrocatalytic performance of Mo 2 C/Mo 3 N 2 /C is attributed to (1) the suitable ratio of Mo 2 C : Mo 3 N 2 and the synergistic effect that well controlled the state of H ads , which is favourable for the Volmer–Heyrovsky/Tafel reaction; (2) the compounds Mo 2 C and Mo 3 N 2 on the nanoscale form abundant heterogeneous nanointerfaces to facilitate electron transfer; (3) the loose and porous structure of Mo 2 C/Mo 3 N 2 /C created more active sites, which facilitated its contact with the electrolyte and also facilitated bubble release. This study provides a novel strategy for the preparation of highly efficient electrocatalysts with heterostructures for HER applications.