Synergistic dual-regulating the electronic structure of NiMo selenides composite for highly efficient hydrogen evolution reaction

Large-scale hydrogen production via electrochemical water splitting is important to renewable energy generation and the global drive toward low carbon emission. However, because of the sluggish kinetics and high energy consumption, efficient and economical electrocatalysts are required for the hydrogen evolution reaction (HER) in order to make it commercially viable. Herein, we present a dual-regulation strategy to optimize the electronic structure of NiMo selenides (NMS) composite for HER. By capitalizing on the electronic interactions between Ni and Mo atoms through the in situ phase separation of Ni0.85Se and MoSe2 from NiMoO4, the electronic configuration is optimized. The selective reduction is simultaneously performed to tune the oxidation states of Ni and Mo, which is more favorable for the adsorption of water molecules and desorption of hydrogen. The NMS electrocatalyst shows an overpotential of 124 mV for a current density of 10 mA cm-2, a small Tafel slope of 63 mV dec- 1 in alkaline electrolytes, Faradaic efficiency of 98.9 % in hydrogen production, as well as excellent longterm stability for 170 h. The results reveal a valuable strategy of synergistic dual-regulating the electronic structure of the active sites to design and prepare inexpensive and high-performance electrocatalysts for alkaline HER and related applications.