Self-assembled ZnIn2S4/SnS2 QDs S-scheme heterojunction for boosted photocatalytic hydrogen evolution: Energy band engineering and mechanism insight

Rapid and efficient transfer and separation of photo-induced carriers are critical for designing environmentally friendly and efficient photocatalysts in catalytic hydrogen evolution. Here, we design a 0D/2D S-scheme heterojunction involving ZnIn2S4 (ZIS) nanosheets self-assembled with SnS2 quantum dots (QDs). The formation of the S-scheme ZIS/SnS2 QDs heterojunction is demonstrated by experimental characteristics and density functional theory (DFT) analyzes, which greatly promotes charge transfer and transport under the interfacial electric field (IEF), lengthens carrier lifetime, enhances light-harvesting properties, and significantly decreases the Gibbs free energy during the catalysis reaction. Therefore, the optimized ZIS/SnS2 photocatalyst achieves a high hydrogen production rate of 1.13 mmol g−1 h−1, which is 16.14 folds the one of pure ZIS. This study provides novel perspectives into the reasonable design of S-scheme photocatalyst by virtue of the theories of energy band engineering and IEF adjustment.