Vacancy-induced spontaneous H2 evolution by overall water splitting on MoTe2/Ti2CO2: A two-dimensional direct Z scheme heterostructure

Photocatalysts with direct Z-scheme heterostructures hold great potential for hydrogen production by solar-driven overall water splitting. However, building highly efficient direct Z-scheme heterostructures is still a challenge. This work develops a novel MoTe2/Ti2CO2 heterostructure as a potential direct Z-scheme photocatalyst for overall water splitting. First-principles computations utilizing density functional theory (DFT) have been used in this study to carefully study several aspects of the heterostructure, including vdW binding energy, formation of the internal electric field, electronic structure, optical properties, and thermodynamic feasibility of water splitting. According to these calculations, the superior interlayer interaction in MoTe2/Ti2CO2 results in a substantial built-in electric field suitable for carrier separation. These findings indicate that the suggested vdW heterostructure is a direct Z-scheme water-splitting photocatalyst with suitable band alignments and a broad light absorption range. This enhanced interaction resulted in a significant increase of photocurrent compared to both the monolayers. Additionally, it is envisaged that the heterojunction will serve as photocatalyst for the oxygen evolution process (OER) and the hydrogen evolution process (HER). The results demonstrate that MoTe2/Ti2CO2 heterostructure with Te vacancy has a low Gibbs free energy of the HER, favoring spontaneous hydrogen evolution in both acidic and neutral conditions. The suggested heterostructure exhibits a commendable solar-to-hydrogen efficiency of 15.25%, making it a viable option for commercial implementation. This research offers a theoretical foundation for designing novel, two-dimensional overall water-splitting photocatalysts in an effort to produce clean energy.