Bilayer MoTe2/XS2 (X = Hf,Sn,Zr) heterostructures with efficient carrier separation and light absorption for photocatalytic water splitting into hydrogen

The photocatalytic water splitting to produce hydrogen has been extensively investigated as one of the most promising means for solving the global energy crisis and environmental problem. In this work, we have designed bilayer two dimensional (2D) van der Waals (vdW) MoTe2/XS2 (X = Hf,Sn,Zr) heterostructures and studied their electronic, optical properties and photocatalytic activities. According to the hybrid density functional computations, these heterojunctions have been found to be stable and potential candidates for direct Z-scheme photocatalysts, where MoTe2 and XS2 layers can be used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Compared with the MoTe2 and XS2 monolayers, MoTe2/XS2 (X = Hf,Sn, Zr) heterostructures with internal electric fields can achieve high-efficiency carriers separation. Meanwhile, these nanocomposites with narrower bandgaps are able to make the best of the sunlight even in the visible light (VIS) region, which is good for enhancing the photocatalytic performance. Therefore, these results have paved the way for exploring efficient MoTe2-based photocatalysts for overall water splitting.