Hydroxyl-modified Nb4C3Tx MXene@ZnIn2S4 sandwich structure for photocatalytic overall water splitting

Abstract

Herein, a hydroxyl-modified MXene@ZnIn2S4 (Nb4C3Tx 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 Nb4C3Tx MXene@ZIS-OH exhibits outstanding catalytic performance, which generates the release rates of hydrogen (53.8 μmol g-1h−1) and oxygen (26.7 μmol g-1h−1) from the water under visible light irradiation. After four photocatalytic cycling, the photocatalytic overall water splitting activity of Nb4C3Tx MXene@ZIS-OH is still 95.9% of the initial activity, which indicates that Nb4C3Tx MXene@ZIS-OH exhibits excellent cycling stability. Notably, the Nb4C3Tx 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 Nb4C3Tx MXene and ZnIn2S4 nanosheets promote the electron transport, inhibit the charge recombination, and separate the generated H2 and O2 with effectiveness. Importantly, the Finite-Difference Time-Domain (FDTD) simulation suggests the hydroxyl groups on the surface of ZnIn2S4 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.