LAUSR

Abstract The development and utilization of photocatalysts to realize water-splitting without any external bias or sacrificial agents has received the limelight. As a novel two-dimensional layered material, metal phosphorus trichalcogenides (MPTs) cause wide research interest, presently. However, the growth of ultrathin two-dimensional MPT crystals is a great challenge to hinder their application. Here, we initially grow few-atomic layered nickel phosphorus trisulfide (NiPS3) as promising photocatalyst for hydrogen evolution. The as-prepared NiPS3 hexagonal nanosheet, as thin as few atomic layers (≤ 3.5 nm), has lateral size of larger than 15 µm. These ultrathin NiPS3 crystals can directly generate hydrogen gas from pure water without any sacrificial agents under sunlight. With ultraviolet photoelectron spectrometer and electrochemical impedance spectroscopy, we show that the attractive photocatalytic activity of the ultrathin NiPS3 crystals arise from their appropriate positions of the band edges. This discovery is expected to make a contribution to develop next generation solar-fuel conversion catalysts for H2 production.