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

Highlights: • MoTe₂/XS₂ (X = Hf,Sn,Zr) heterojunctions are suitable for photocatalytic overall water splitting. • These heterojunctions possess strong redox ability. • The induced electric fields can promote the migration of interfacial photoinduced carriers. • The optical spectra of these nanocomposites have significantly enhanced in the visible region. 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.