Promoting photocatalytic H2 evolution through interfacial charge separation on the direct Z-scheme ZnIn2S4/ZrO2 heterojunction

Reasonably constructing direct Z-scheme heterojunction photocatalysts is the most essential issue for enhancing the capacity of photocatalytic hydrogen evolution (PHE). Based on outstanding visible light response and photocatalytic capacity of ZnIn2S4, as well as unique photoelectrochemical properties of ZrO2, a direct Z-scheme ZnIn2S4/ZrO2 heterojunction photocatalyst system has been built up by hydrothermal process for PHE for the first time. The PHE rate of the optimal catalyst ZnIn2S4/ZrO2 heterojunction can achieve 9319 μmol g−1 h−1, which is 3.5 times or 2330 times that of virginal ZnIn2S4 (2679 μmol g−1 h−1) or ZrO2 (4 μmol g−1 h−1), and an AQE at 365 and 420 nm are 16.35% and 4.92%, respectively. The boosted photocatalytic properties can be ascribed to the direct Z-scheme heterojunction to accelerate photo-induced carrier separation, which is beneficial to the generation of active sites. Meanwhile, a direct Z-scheme photo-induced carrier exchange mechanism is verified by ISI-XPS, DFT calculation and EPR test. This strategy will provide an efficient scheme for reasonably constructing direct Z-scheme heterojunction photocatalysts with superior hydrogen evolution properties.