Visible-light-driven Z-scheme photocatalysts integrated with two-dimensional (2D) ultrathin semiconductor nanosheets (NSs) are promising for efficient solar fuel production; however, enhancing Z-scheme photocatalysis via controllable vacancy modulation is still underdeveloped to date. Herein, a sulfur vacancy (SV)-engineered CdS ultrathin NS/MoSe2 few-layered NS 2D/2D heterojunction with tight Mo-S bond linkages was constructed, whose Z-scheme charge-transfer pathway was revealed through in situ light-irradiated X-ray photoelectron spectroscopy, surface photovoltage spectroscopy, and radical production analysis. Notably, density functional theory calculations revealed that SV could serve as the active site for H2 production. Moreover, by modulating the SV content to broaden the Fermi level gap of the components, the Z-scheme charge transport efficiency of the CdS-MoSe2 heterojunction increased, affording a visible-light (λ > 400 nm) photocatalytic H2 evolution activity as high as 47.52 mmol g-1 h-1 (apparent quantum yield of 22.9% at 400 nm), which is approximately 12.2- and 7.1-fold higher than that of CdS and 3 wt% Pt-loaded CdS, respectively. The results of this study provide useful insights for boosting photocatalytic capability via vacancy-engineering-reinforced Z-scheme charge transfer.
Zeng et al. (Thu,) studied this question.