SeWS/bilayer-SiC heterojunction: An S-scheme photocatalyst with high visible-light absorption, excellent carrier mobility and adjustable band gap

Vertically stacked heterojunctions have garnered significant attention for their tunable electronic structures and photocatalytic performance, making them promising candidates for next-generation nanodevices. Using first-principles calculations, we systematically investigate the electronic structure, optical characteristics, and charge transfer of WSSe/SiC heterojunctions. Our results reveal that SeWS/monolayer-SiC, SeWS/bilayer-SiC, and SWSe/monolayer-SiC exhibit type-II band alignment, whereas SWSe/bilayer-SiC displays type-I alignment. Notably, SeWS/bilayer-SiC possesses a direct bandgap, in contrast to the indirect bandgaps of the other three configurations. Remarkably, the SeWS/bilayer-SiC heterojunction demonstrates a high absorption coefficient (10 5 cm −1 ) in the visible range and exhibits exceptional anisotropy in carrier transport, with an outstanding hole mobility of 9.58 × 10 3 cm 2 V −1 s −1 along the Y direction. Furthermore, by combining thermodynamic stability with the S-type charge transfer mechanism, this system demonstrates outstanding redox capabilities in photocatalytic water splitting, showing a hydrogen production efficiency potential of up to 22.15%, exceeding the commercial feasibility threshold (10%). Additionally, we have also demonstrated that external electric fields and biaxial strain can effectively regulate the band gap, and the optical absorption coefficient exhibits a strong dependence on strain. This work provides fundamental insights for designing WSSe/SiC heterojunctions for efficient photocatalysis and tunable photodetector applications.