Tuning the charge transfer route by p–n junction catalysts embedded with CdS nanorods for simultaneous efficient hydrogen and oxygen evolution

Abstract

Overall solar water splitting into H₂ and O₂ using visible light responsive photocatalyst has been considered as a clean, green, and renewable system. CdS with a suitable bandgap (2.25 eV) and band position was for a long time not considered as a promising candidate for overall solar water splitting because of its serious photo-corrosion and rapid charge recombination, although it has considerable photocatalytic activity for H₂ generation in a sacrificial agent containing electrolyte. Here, we design a new sandwich-like architecture using CdS nanorods embedded in a p–n junction of MoS₂/N-RGO which serves as a novel photocatalytic system that could promote overall water splitting in natural water. It was found that the p–n junction of MoS₂/N-RGO not only works as the HER and OER electrocatalyst for H₂ and O₂ generation respectively, but also facilitates charge separation by its inner electric field. Compared to well-defined thermodynamically favored charge transport, the new charge transfer route in MoS₂/CdS/N-RGO splits natural water, resulting in an essential change of the carrier separation mechanism and high anti-corrosion.