Coupling interactions enhancing molybdenum-based electrocatalysts for high-efficiency hydrogen evolution at wide pH

Hydrogen energy can be a promising alternative to fossil energy and can be applied to address the global energy challenge. However, the large overpotential and limited operation in the single electrolyte for hydrogen evolution reaction (HER) greatly hinder its practical applications. Herein, an efficient HER electrocatalyst demonstrated as MoO2-Mo2C-NC (NC is nitrogen-doped carbon) heterostructure applied in a wide pH, was in-situ constructed on carbon cloth (CC) by controlling coupling interactions of multicomponents. The strong coupling interactions in the heterostructure triggered the strain effect to induce C atoms to absorb H and promoted the establishment of a distinct synergy effect between Mo and C atoms, resulting in further electron configuration regulation. Besides, C defects and O vacancies of catalyst developed a rich H3O+ environment in alkaline media, improving H-seizure of active sites. As expected, MoO2-Mo2C-NC@CC-950 °C achieved 10 mA·cm−2 only with 72 mV in 0.5 M H2SO4, 206 mV in 1 M phosphate buffer solution (PBS) and 79 mV in 1 M KOH, respectively, corresponding to the Tafel slopes of 56.42, 133.42 and 59.7 mV∙dec-1. In addition, stability test in 1 M KOH performed at 100 mA∙cm−2 for 120 h exhibited ultrahigh durability in HER. The high-performance was attributed to the synergy of Mo and C atoms and the key roles of C defects and O vacancies, which were verified by the density functional theory (DFT) calculations. This work presents fresh possibilities for multicomponent modification and mechanism exploration in HER electrocatalysts.