Two-dimensional P₂S-I monolayer as a promising photocatalyst for overall water splitting

Based on density functional theory, the crystal structure, electronic properties, and photocatalytic performance of 2D P₂S-I monolayer were studied. It has a 2.602 eV indirect bandgap, consistent with the requirements for visible-light-driven overall water splitting. Direction-dependent charge transport calculations show high carrier mobilities (∼1768 cm² V^-1 s^-1 for electrons along the x-direction and ∼605 cm² V^-1 s^-1 for holes along the y-direction). The calculation of the optical absorption coefficient reveals strong absorption in the visible and ultraviolet regions. Thermodynamic simulations confirm spontaneous water oxidation under illumination, as well as reduced activation energies for hydrogen evolution in both acidic and neutral environments. The achieved solar-to-hydrogen efficiency of up to 14.7% stems from optimized photon utilization and charge separation dynamics. These results highlight its potential in renewable energy systems and provide strategic insights for developing advanced 2D photocatalysts.