Few-Layer P ₄ O ₂: A Promising Photocatalyst for Water Splitting

Photocatalytic water splitting by a two-dimensional material is a promising technology for producing clean and renewable energy. Development of this field requires candidate materials with desirable optoelectronic properties. Here, we present a detailed theoretical investigation of the atomic and electronic structure of few-layer P ₄ O ₂ systems to predict their optoelectronic properties. We predict that the three-layer P ₄ O ₂ with normal packing (α-3), ingeniously combining all desired optoelectronic features, is an ideal candidate for photocatalytic water splitting. It fascinatingly bears nearly a direct band gap (1.40 eV), appropriate band edge position, high solar-to-hydrogen efficiency (17.15%), high sunlight absorption efficiency, and ultrahigh carrier mobility (21 460 cm ² V ^-1 s ^-1 ) at room temperature. These results make three-layer P ₄ O ₂ a promising candidate for photocatalytic water splitting.