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

Photocatalytic water splitting by two-dimensional (2D) 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 P4 O2 systems to predict their optoelectronic properties. We predict that the three-layer P4 O2 with normal packing (α-3), ingeniously combining all desired optoelectronic features, is an ideal candidate for photocatalytic water splitting. It fascinatingly bears nearly direct band gap (1.40 eV), appropriate band edge position, high solar-to-hydrogen (STH) efficiency (17.15%), high sunlight absorption efficiency, and ultrahigh carrier mobility (21460 cm2 V-1 s-1 ) at room temperature. These results make three-layer P4 O2 a promising candidate for photocatalytic water splitting.