Two-dimensional M2CO2/MoS2 (M = Ti, Zr and Hf) van der Waals heterostructures for overall water splitting: A density functional theory study

Because of the wide applications for photocatalysis, electronics and optoelectronics, two-dimensional (2D) van der Waals (vdW) heterojunctions have attracted substantial attentions. In this work, we carried out a systematic investigation on the geometry structures, electronic properties, optical properties and carrier mobilities of the M2CO2-II (M = Ti, Zr and Hf) and MoS2 heterostructures with a hybridized density functional theory (DFT). The B'C' stacked M2CO2-II/MoS2 heterostructure with a short interlayer distance is energetically favorable. All M2CO2-II/MoS2 bilayer and sandwich-like structures are indirect semiconductors. The maximum of valence band (VBM) and conduction band minimum (CBM) of M2CO2-II/MoS2 heterostructures are dominated by different layers, implying the spatial separation of photogenerated electron-hole pairs. Three M2CO2-II/MoS2 heterostructures, including Zr2CO2-II/MoS2 -S-B'C', Hf2CO2-II/MoS2-B-B'C', and Hf2CO2-II/MoS2-S-B'C', are considered as the promising candidates for overall water splitting due to their appropriate band structures, suppressed recombination of photogenerated electron-hole pairs, enhanced optical absorption and carrier mobilities. In addition, the gaint hole mobility makes Ti2CO2-II/MoS2 heterostructure a potential candidate for the application for 2D electronic devices.