A promising photocatalyst for water-splitting reactions with a stable sandwiched P ₄ O ₂ /black phosphorus heterostructure and high solar-to-hydrogen efficiency

/BP systems, we found that the O-1-P system with intrinsic electric field ingeniously combines all the desired features for photocatalytic water-splitting reactions, including small direct band gap (1.34 eV), low exciton binding energy, high hole mobility and ultrahigh solar-to-hydrogen efficiency as high as 22.77%. Through Gibbs free energy calculations, the active sites and possible reaction pathways of full water-splitting reactions were also confirmed. Our work offers useful guidance for designing and fabricating stable 2D materials with high performance for application in photocatalytic water-splitting reactions.