Hydroxyl-modified NbCT MXene@ZnInS sandwich structure for photocatalytic overall water splitting.

Herein, a hydroxyl-modified MXene@ZnInS (NbCT MXene@ZIS-OH) overall water splitting photocatalyst with a sandwich structure was prepared through an in-situ growth strategy and peroxyl plasma post-treatment. The NbCT MXene@ZIS-OH exhibits outstanding catalytic performance, which generates the release rates of hydrogen (53.8 μmol gh) and oxygen (26.7 μmol gh) from the water under visible light irradiation. After four photocatalytic cycling, the photocatalytic overall water splitting activity of NbCT MXene@ZIS-OH is still 95.9% of the initial activity, which indicates that NbCT MXene@ZIS-OH exhibits excellent cycling stability. Notably, the NbCT MXene@ZIS-OH achieves an AQY of 1.2% for the overall photocatalytic water splitting at 380 nm. The sandwich structure and matched heterointerface between high work function NbCT MXene and ZnInS nanosheets promote the electron transport, inhibit the charge recombination, and separate the generated H and O with effectiveness. Importantly, the Finite-Difference Time-Domain (FDTD) simulation suggests the hydroxyl groups on the surface of ZnInS could increase the hydrophilicity of photocatalyst and capture the holes generated by photoexcitation, thereby promoting the separation of electron-hole pairs rapidly. This work presents a successful example of constructing overall water splitting photocatalysts by energy level regulation, structure design and functional group modification.