Reversing Free-Electron Transfer of MoS Cocatalyst for Optimizing Antibonding-Orbital Occupancy Enables High Photocatalytic H Evolution.

The interaction between a co-catalyst and photocatalyst usually induces spontaneous free-electron transfer between them, but the effect and regulation of the transfer direction on the hydrogen-adsorption energy of the active sites have not received attention. Herein, to steer the free-electron transfer in a favorable direction for weakening S-H bonds of sulfur-rich MoS , an electron-reversal strategy is proposed for the first time. The core-shell Au@MoS cocatalyst was constructed on TiO to optimize the antibonding-orbital occupancy. Research results reveal that the embedded Au can reverse the electron transfer to MoS to generate electron-rich S active sites, thus increasing the antibonding-orbital occupancy of S-H in the Au@MoS cocatalyst. Consequently, the increase in the antibonding-orbital occupancy effectively destabilizes the H 1s-p antibonding orbital and weakens the S-H bond, realizing the expedited desorption of H to rapidly generate a lot of visible H bubbles. This work delves deep into the latent effect of the photocatalyst carrier on cocatalytic activity.