Dual-Defective SnS₂—A Promising 2D Photocatalyst for Water Splitting Toward Hydrogen Fuel

Solar-to-hydrogen fuel conversion through photocatalytic water splitting is a promising green pathway for achieving carbon-neutral and net-zero targets worldwide. In this regard, designing efficient photocatalytic materials that can efficiently split water into hydrogen is essential. Using First-principles calculations based on the density functional theory (DFT), we demonstrate that the dual-defective SnS₂ (Ni-SnS₂-V_S), incorporating both nickel doping and sulfur vacancy, becomes a promising 2D photocatalyst semiconductor compared with pure SnS₂. In particular, the Ni-SnS₂-V_S monolayer not only displays suitable band alignment that perfectly overcomes the redox potentials for overall water splitting, but also exhibits enhanced photocatalytic activity, spatial separation of charge carriers (electrons and holes), and a broadened optical absorption spectrum. Therefore, the dual-defective SnS₂ can serve as an efficient photocatalyst for overall water splitting to produce hydrogen fuel. Remarkably, the dual-defect method can be an effective strategy to enhance the electronic and catalytic behaviors of 2D materials, offering atomic-scale guidance for the development of solar-fuel generation.