Activating the MoS2 Basal Plane toward Enhanced Solar Hydrogen Generation via in Situ Photoelectrochemical Control

Developing robust, low-cost, and scalable catalysts for photo-electrochemical (PEC) water splitting devices is crucial for the sustainable hydrogen evolution reaction (HER). MoS2 has emerged as a potent alternative to Pt-based catalysts for the HER. However, the active sites of 2H-MoS2 are reported to locate at the edges, leaving a large number of inert basal planes useless. Herein, a facile strategy is reported to activate the MoS2 basal plane via an in situ PEC protocol. Both experimental studies and theoretical calculations reveal the emergence of O-Mo-S sites on the MoS2 basal planes, which enable not only enhancing its intrinsic conductivity but also modulating the adsorption behavior of H atoms and consequent HER activity. As a result, the MoS2-decorated Si photocathodes exhibit an applied bias photon-to-current efficiency of 4.9% under the simulated AM1.5G illumination. This study offers a potential scalable route for the fabrication of high-performance and precious metal-free solar-to-fuel devices.