Two-dimensional M 2 CO 2 /MoS 2 ( 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 M 2 CO 2 -II ( M  = Ti, Zr and Hf) and MoS 2 heterostructures with a hybridized density functional theory (DFT). The BʹCʹ stacked M 2 CO 2 -II/MoS 2 heterostructure with a short interlayer distance is energetically favorable. All M 2 CO 2 -II/MoS 2 bilayer and sandwich-like structures are indirect semiconductors. The maximum of valence band (VBM) and conduction band minimum (CBM) of M 2 CO 2 -II/MoS 2 heterostructures are dominated by different layers, implying the spatial separation of photogenerated electron-hole pairs. Three M 2 CO 2 -II/MoS 2 heterostructures, including Zr 2 CO 2 -II/MoS 2 –S-BʹCʹ, Hf 2 CO 2 -II/MoS 2 –B-BʹCʹ, and Hf 2 CO 2 -II/MoS 2 –S-BʹCʹ, 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 Ti 2 CO 2 -II/MoS 2 heterostructure a potential candidate for the application for 2D electronic devices.