Charge Redistribution of CoS/MoS Heterojunction Microsphere Enhances Electrocatalytic Hydrogen Evolution.

The electrocatalytic hydrogen evolution activity of transition metal sulfide heterojunctions are significantly increased when compared with that of a single component, but the mechanism behind the performance enhancement and the preparation of catalysts with specific morphologies still need to be explored. Here, we prepared a CoS/MoS heterojunction with microsphere morphology consisting of thin nanosheets using a facile two-step method. There is electron transfer between the CoS and MoS of the heterojunction, thus realizing the redistribution of charge. After the formation of the heterojunction, the density of states near the Fermi surface increases, the -band center of the transition metal moves downward, and the adsorption of both water molecules and hydrogen by the catalyst are optimized. As a result, the overpotential of CoS/MoS is superior to that of most relevant electrocatalysts reported in the literature. This work provides insight into the synergistic mechanisms of heterojunctions and their morphological regulation.