Sulfur vacancy-regulated interface charge transfer for boosting photocatalytic hydrogen evolution over Bi <sub>2</sub> S <sub> 3− <i>x</i> </sub> @Cd <sub>0.7</sub> Zn <sub>0.3</sub> S hollow hexagonal nanocages
Xiaofeng Sun, Tao Xian, Junqin Zhang, Jinyuan Ma, Shifa Wang, Zao Yi, Guorong Liu, Babak Kakavandi, Hua Gui Yang
Abstract
Abstract How to tailor the interface charge transfer in heterostructured photocatalysts via energy band engineering has been an important research topic in boosting photocatalysis and promoting its application in hydrogen evolution. In this study, we have developed Bi2S3−[email protected] (BS-Sv@CZS, Bi2S3−x with S vacancies labeled as BS-Sv) heterostructured photocatalysts, where the energy band structures of BS-Sv were continuously regulated via creating S vacancies in the lattice to realize manipulation of the interface charge transfer and boost the photocatalysis for H2 generation. The BS-Sv@CZS photocatalysts are constructed into double-shell hollow hexagonal nanocages with BS-Sv coating on the outer surface of CZS nanocages. It is demonstrated that with increasing the S vacancy concentration in BS-Sv (i.e., elevating the energy band positions of BS-Sv), the interface electric field of BS-Sv@CZS gradually increases; and more importantly, the photoelectron transfer behavior from CZS to BS-Sv is tailored from conduction band (CB)-to-CB transfer to CB-to-CB/valence band (VB) transfer, and then to CB-to-VB transfer. The BS-Sv@CZS heterostructured photocatalysts are endowed with much improved photocatalysis for H2 evolution; particularly, the BS-Sv2@CZS with CB-to-CB/VB photoelectron transfer displays the highest photocatalytic activity (H2 generation rate: 2.56 mmol·g−1·h−1) that is 4.1 (or 8.0) times larger than that of CZS (or BS-Sv2). The photocatalytic enhancement mechanism was deeply elucidated via combined experimental and theoretical studies. This study highlights an important strategy for boosting photocatalytic H2 evolution of heterostructured photocatalysts.