Construction of novel NH2-MIL-125(Ti)@ZnIn2S4 Z-scheme heterojunction and its photocatalytic performance regulation

In this work, a series of ZnIn2S4 nanosheets encapsulated NH2-MIL-125(Ti) heterostructures (NM-125(Ti)@ZIS) have been rationally designed and established through a facile oil bath method. The photocatalytic Cr(VI) reduction and H2 evolution performance on NM-125(Ti)@ZIS were elaborately modulated by adjusting the mass ratio of two components, introducing S vacancy and loading cocatalysts. The experimental results demonstrate that the optimized NM-125(Ti)@ZIS heterostructure with mass ratio 3:1 of NM-125(Ti) to ZIS has an excellent Cr(VI) reduction performance in neutral solution, giving 98% reduction efficiency within 60 min. Moreover, the NM-125(Ti)@ZIS heterostructure, following the introduction of sulfur vacancies and the incorporation of Pt nanoclusters, demonstrates an optimal visible light (λ > 420 nm) hydrogen evolution rate of 4.708 mmol/g/h, which is 5.82 times greater than that of pristine ZIS. A thorough investigation of the microstructures and photoelectrochemical properties of the NM-125(Ti)@ZIS heterostructures reveals that the intimate contact interface, sulfur vacancy, and Pt nanocluster serve to effectively enhance charge separation efficiency, thereby improving the photocatalytic performance. Further analysis on the charges behavior at the interface verifies that a novel Z-scheme heterojunction has been constructed between ZnIn2S4 and NH2-MIL-125(Ti).