Ultrathin 1T/2H mixed phase MoS2 decorated TiO2 nanorod arrays for effective photocatalytic hydrogen evolution

Abstract

Ultrathin mixed metallic phase (1T) and semiconducting phase (2H) MoS₂ nanosheet decorated TiO₂ nanorod arrays were prepared through a simple two-step hydrothermal method. By modulating the subsequent annealing conditions, the gradual phase transformation of MoS₂ from 1T to 2H was observed. The mixed phase MoS₂ shows superior photocatalytic hydrogen evolution to 2H phase MoS₂ and noble metal Pt. The distinguishable optical and photoelectrochemical behaviors of mixed phase MoS₂ and 2H phase MoS₂ reflect their different internal structures and charge transfer mechanisms. The existence of the abundant metal like 1T phase in the mixed phase MoS₂ accelerates the electron transport between TiO₂ and MoS₂ more effectively and decreases the recombination of electron–hole pairs, thus enabling preferable photocatalytic performance compared to 2H phase MoS₂. The possible electron transfer mechanism between MoS₂ and TiO₂ is also illustrated.