Transient Metal Centers at the Covalent Heterointerface Favor Photocatalytic Hydrogen Evolution
Yuhua Zhang, Chuchu Cheng, Fangshu Xing, Ze Li, Caijin Huang
Abstract
Semiconductor heterostructures effectively promote the transfer and separation of interfacial photoinduced charges for the photocatalytic process. Herein, we constructed a direct Z-scheme SnSe 2 /CdS heterojunction photocatalyst. N-type SnSe 2 semiconductors are suitable candidate materials for oxidation half-reactions in Z-scheme heterojunctions. The intimate atomic-level interfacial contact through Cd–Se bonds provides a better interfacial charge transport channel for the photoinduced charges. Moreover, the transient Sn 4+ /Sn 0 centers caused by the photoredox process boost the interfacial charge transport/separation at the interface. Besides, the presence of S vacancies acting as electron enrichment centers further enhances the redox ability for hydrogen production. Therefore, the SnSe 2 /CdS heterostructure showed a superior visible-light photocatalytic H 2 -production activity of 13.6 mmol·g –1 ·h –1 using ascorbic acid as a sacrificial agent, which is 9.7 times higher than that of pristine CdS. The apparent quantum yield reaches 10.5% at λ = 420 nm. This work provides a useful way to improve charge transfer in the Z-scheme heterojunction photocatalyst for hydrogen production.