Heterojunction Engineering of Multinary Metal Sulfide‐Based Photocatalysts for Efficient Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution (PHE) via water splitting using semiconductor photocatalysts is an effective path to solve the current energy crisis and environmental pollution. Heterojunction photocatalysts, containing two or more semiconductors, exhibit better PHE rates than those with only one semiconductor owing to the altered band alignment at the interface and stronger driving force for charge separation. Traditional binary metal sulfide (BMS)-based heterojunction photocatalysts, such as CdS, MoS2 , and PbS, demonstrate excellent PHE performance. However, the recently developed multinary metal sulfide (MMS)-based photocatalysts possess favorable chemical stability, tunable band structure, and flexible element compositions, and have considerable potential to realize higher PHE rates than those of BMSs. In this review article, the mechanism of PHE is first elucidated and then various single and heterojunction MMS-based photocatalysts and their charge transfer behaviors and PHE performances are systematically summarized. A perspective on potential future research directions in this field is concluded.