In-situ Mo doped ZnIn2S4 wrapped MoO3 S-scheme heterojunction via Mo-S bonds to enhance photocatalytic HER

Abstract

The construction of ZnIn2S4 based heterogeneous structure combined with in-situ relatively metal doping remains a great challenge. A direct Step-scheme (S-scheme) of in-situ Mo doped ZnIn2S4 wrapped MoO3 (MoO3@Mo-ZIS) was prepared in this work based on the thermal solubility properties of MoO3. The optimized photocatalyst of MoO3@Mo-ZIS exhibits superior H2 evolution rate of 5.5 mmol/g/h without co-catalysts, which is the 6.5 and 1.3 times of ZIS and 40 Mo doped ZIS (40 Mo-ZIS), respectively. The excellent photocatalytic activity was attributed to the Mo doping and formation of Mo-S species. The density functional theory (DFT) calculations demonstrate that the Mo-S species would form a new hybridized state near the Fermi level, reducing the ΔGH* to enhance photocatalytic hydrogen evolution reaction (HER). Furthermore, the direct S-scheme heterojunction of MoO3@Mo-ZIS confirmed by Electron paramagnetic resonance (EPR) and Kelvin probe force microscopy (KPFM) promotes photogenerated carrier separation, thus enhancing the performance of photocatalytic HER.