High-Throughput\nComputing of Janus Chalcogenides\nas Photocatalysts and\nPiezoelectric Materials for Overall Water Splitting

The presence of the intrinsic fields in two-dimensional\n(2D) materials\nholds promise for photocatalysts, as it diminishes the band gap requirements\nof 1.23 eV and accelerates the separation of the photogenerated carriers.\nInspired by the extensive application in MA<sub>2</sub>X<sub>4</sub> families, we predict Janus ZMXAY derived from MA<sub>2</sub>X<sub>4</sub> materials to introduce intrinsic fields suitable for photocatalysts\nfrom 512 candidates. These monolayers also exhibit high mobilities\nup to ∼10<sup>4</sup> cm<sup>2</sup>V<sup>–1</sup>s<sup>–1</sup> with strong anisotropy, and are accompanied by the\ninherent piezoelectric properties. Notably, all monolayers, except\nJanus SMoPGeAs, SeMoPSiAs, and SeMoPGeAs, demonstrate suitable band\ngaps (0.88–1.43 eV) and appropriate band edge positions without\nthe need for any external potential to drive spontaneous overall water\nsplitting. It also demonstrates visible optical absorption capacity\nand high solar-to-hydrogen conversion efficiency (16.06–41.08%).\nOur work identifies ideal candidates for multifunctional devices and\nprovides theoretical guidance for future experimental research and\napplication development.