Abstract: Recently, Yu and co-workers deeply explore the potential impact of free electron transfer between cocatalysts and photocatalyst carriers on H₂ evolution efficiency of active sites over MoS_2+x. They propose an electron-reversal tactics to evade the unexpected electron transfer and synchronously regulate the above transfer in a beneficial orientation for weakening hydrogen adsorption on S sites. Herein, this highlight not only discusses and summarizes the essences of electron reversal and the optimized H adsorption/desorption mechanism, but also emphasizes the significance of femtosecond transient absorption spectroscopy (fs-TAS) and in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) for revealing charge transfer dynamics and processes. We anticipate that this highlight can disseminate a new perspective on the roles of photocatalyst carriers in improving cocatalytic H₂-production kinetics.

Key words: Photocatalysis, Cocatalyst, Electron reversal, Antibonding-orbital occupancy, S—H bonds