Efficient photocatalytic hydrogen evolution of g-C₃N₄/Vs-SnS₂/CdS through a sulfur vacancy-rich SnS₂ induced charge storage effect

Photocatalytic hydrogen production using semiconductors is one of the most promising routes for sustainable energy production. However, poor electron-hole separation and slow surface reactions of photocatalysts impede their performance. Here, a hierarchical hollow g-C₃N₄/Vs-SnS₂/CdS tandem heterojunction photocatalyst was constructed. For the first time, the charge storage characteristics of S-vacancy-rich SnS₂ in photocatalytic applications were developed. Due to the charge storage properties of Vs-SnS₂, more electrons accumulate on the surface of Vs-SnS₂, which greatly improves the separation efficiency of charge carriers and prolongs the lifetime of charge carriers. The aggregation of electrons leads to the formation of Cd-S-OH chemical bonds, which is beneficial for the adsorption and activation of H₂O. As a result, this catalyst shows an excellent photocatalytic hydrogen evolution rate of 2.3 mmol h⁻¹ g⁻¹. Encouragingly, electron storage signals were detected in the femtosecond transient absorption spectra of heterojunctions, and it was proved that the electrons stored in Vs-SnS₂ could be utilized in the photocatalytic process. This provides new insights into the electron capture and storage process of semiconductors with electron storage properties during photocatalysis.