Ion-sharing interface and directional doping synergize N-MoS₂/Se-CoS₂ catalyst for efficient hydrogen evolution

Interfacing and doping can effectively harmonize the electronic and coordination states of active centers in the electrocatalysts. Herein, we prepare heterostructured N-MoS₂/Se-CoS₂ electrocatalyst with ion-sharing interfaces and directional doping to activate inert basal phases for hydrogen evolution reaction (HER). Based on experimental and theoretical results, their synergistic effects on electron redistribution, electronic structure and coordination chemistry are investigated; furthermore, roles of each component and bridged Mo-S-Co sites at the phase interfaces as active sites in optimizing the adsorption/desorption of essential reaction intermediates H* and OH^–, as well as the free energies of unit reaction steps in the HER, are elucidated in depth. The N-MoS₂/Se-CoS₂ catalyst needs only 37 mV to give current density of 10 mA cm⁻² with a low Tafel slope of 49.4 mV dec⁻¹; more importantly, the catalyst delivers a long-term durability for HER in alkaline condition and comparable performance with commercial RuO_2||Pt/C system in a two-electrode assembled electrolyzer. This work provides more insights into the design and preparation of high-performance heterostructured electrocatalysts.