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

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.