Covalently Linking Reduced Graphene Oxide Facilitated Electrodeposition of MoS on Silicon Pyramidal Photocathode To Enhance Hydrogen Evolution.

In recent years, increasing attention has been paid to photoelectrochemical (PEC) hydrogen production owing to the utilization of sustainable solar energy and its promising performance. Silicon-based composites are generally considered ideal materials for PEC hydrogen production. However, slow reaction kinetics and poor stability are still key factors hindering the development of silicon-based photoelectrocatalysts. Herein, we present an n-p Si pyramidal photocathode assembly method to load reduced graphene oxide (rGO) onto the surface of the n-p Si pyramid by covalently linking (Si/rGO). rGO is utilized as a conductive layer to reduce the interfacial charge-transfer resistance. Then, MoS can be successfully electrodeposited on the surface of Si/rGO to form the Si/rGO/MoS composite, which possesses excellent PEC hydrogen evolution performance with a high and stable photocurrent of -41.6 mA cm and a hydrogen evolution rate of about 18.1 μmol min cm under 0 V (vs RHE). The covalently linking rGO layer effectively enhances the transfer of photogenerated carriers between the Si substrate and MoS. MoS provides abundant hydrogen evolution active sites, which accelerate the surface reaction kinetics, as well as a protective layer for the Si pyramidal array structure. This work provides a low-cost, convenient, and efficient way of preparing silicon-based photocathodes.