Collaborative effect between single-atom Re and S vacancy on modulating localized electronic structure of MoS₂ catalysts for alkaline hydrogen evolution

Optimizing the catalytic activity and stability of molybdenum disulfide (MoS2) towards alkaline hydrogen evolution reaction (HER) is significant for sustaining green hydrogen. A moderate localized electronic structure of active sites plays a crucial role in determining the activity and stability of the catalysts, yet how to construct such localized electronic structure still remains indeterminacy. Enlightened by theoretical prediction, herein, the introduction of both single-atom Re and the adjacent S vacancy in MoS₂ (denoted as Re-MoS₂-Vs) exhibits collaborative effect on regulating the localized electronic structure of active sites (viz. Re-(S, Vs)-Mo). Such regulated electronic structure helps to decrease the energy barrier of the water dissociation and optimize hydrogen adsorption energy for enhancing alkaline HER performance. Most importantly, Mo-S bonds in the above local Re-(S, Vs)-Mo configurations are also strengthened for preventing the leaching of Mo and S atoms and then ensuring the long-time stability. Consequently, the deliberately designed Re-MoS₂-Vs with a Re coordination number of ~ 5.0 is experimentally verified to exhibit a comparable electrocatalytic performance and robust operational stability over 120 h. This strategy provides a promising guidance for modulating the electronic structure of MoS2 based catalysts via double-tuning atomic-scale local configuration for HER applications.