Tunable Z-Scheme Photocatalytic Activity in Sc2CBrX/MoTe2 (X = Br, Cl) Heterostructures: A Combined Electronic and Non-Adiabatic Dynamics Study

Z-scheme photocatalytic heterostructures are investigated based on four configurations derived from Sc2CBr2/MoTe2 and Sc₂CClBr/MoTe2 systems. In the Sc2CBr2/MoTe2 structures, relative interlayer sliding is introduced, while in the Sc2CClBr/MoTe2 counterparts, inversion of the monolayer is applied. All configurations are screened for geometric compatibility, and their thermodynamic stability is confirmed. For each structure, the band alignment and the direction of the built-in electric field are found to satisfy the criteria of the Z-scheme water splitting. Strain effects are observed to be more pronounced in Sc2CBr2/MoTe2 than in Sc2CClBr/MoTe2. The solar-to-hydrogen (STH) efficiency for the two considered configurations of the Sc2CBr2/MoTe2 becomes smaller with compressive strain but larger with tensile strain, reaching 25.42% and 25.71% at 4% tensile strain, respectively. In the hydrogen evolution reaction, the Gibbs free energies range from 1.27 to 1.47 eV, while those for the rate-limiting steps of the oxygen evolution reaction lie between 2.83 and 3.38 eV across the four configurations. These energy barriers are considered achievable under the additional applied voltage conditions, suggesting thermodynamic feasibility. In non-adiabatic molecular dynamics simulations, the MoTe2/Sc2CBr2 heterostructure demonstrates a combination of faster electron–hole recombination and prolonged carrier lifetimes, a feature favorable for Z-scheme charge transfer, demonstrating strong potential for high-performance photocatalytic water splitting.