High-Throughput Computing of Janus Chalcogenides as Photocatalysts and Piezoelectric Materials for Overall Water Splitting

The presence of the intrinsic fields in two-dimensional (2D) materials holds promise for photocatalysts, as it diminishes the band gap requirements of 1.23 eV and accelerates the separation of the photogenerated carriers. Inspired by the extensive application in MA₂X₄ families, we predict Janus ZMXAY derived from MA₂X₄ materials to introduce intrinsic fields suitable for photocatalysts from 512 candidates. These monolayers also exhibit high mobilities up to ∼10⁴ cm²V^–1s^–1 with strong anisotropy, and are accompanied by the inherent piezoelectric properties. Notably, all monolayers, except Janus SMoPGeAs, SeMoPSiAs, and SeMoPGeAs, demonstrate suitable band gaps (0.88–1.43 eV) and appropriate band edge positions without the need for any external potential to drive spontaneous overall water splitting. It also demonstrates visible optical absorption capacity and high solar-to-hydrogen conversion efficiency (16.06–41.08%). Our work identifies ideal candidates for multifunctional devices and provides theoretical guidance for future experimental research and application development.