Unveiling the potential of two-dimensional Janus ScXAlY (X/Y=P, As) materials and heterostructures in visible-light-driven photocatalytic water splitting

Two-dimensional (2D) material with Janus-induced built-in electric field, has become a research focus arising from their characteristic physical and chemical properties, especially in photocatalytic water splitting applications. Herein, we introduce a novel family of 2D Janus materials, named ScXAlY (X/Y = P, As), and prove these Janus materials and their heterostructures as promising water splitting photocatalytic candidate materials, leveraging first-principles calculations. All Janus structures and heterostructures exhibit strong dynamical, thermal, and mechanical stabilities. These 2D Janus ScXAlY materials possess wide band gaps, excellent electronic carrier mobilities, and appropriate band edges to facilitate overall water splitting, and moreover can attain Janus-induced built-in electric field effect. Interestingly, the heterostructures (ScXAlY/ScXAlY) surpass the individual materials in performance, demonstrating enhanced solar-to-hydrogen (STH) efficiencies (>30 %) and increscent electrostatic potential differences (>0.85 eV). Furthermore, they show comprehensive photoabsorption across the visible light spectrum, with peak absorptions more than doubling those of the single materials. These heterostructures also display effective spatial separation of electrons and holes which can further boosting their photocatalytic capabilities. Our findings underscore the potential of Janus ScXAlY materials and their heterostructures, in facilitating visible-light-driven photocatalytic water splitting, showcasing a promising avenue for advancement in this burgeoning field.