Manganese phosphorous trifulfide nanosheets and nitrogen doped carbon dot composites with manganese vacancies for a greatly enhanced hydrogen evolution.

As a novel chalcogenide photocatalyst, MnPS suffered from limited visible light absorption, high photogenerated electron-hole recombination, and low hole oxidation capability due to its high valence band (VB) potential. In this work, the novel MnPS nanosheets-Nitrogen-doped carbon dots (NCDs) composites were fabricated by immobilizing NCDs with terminal amine groups on Na intercalated MnPS nanosheets for a greatly enhanced photocatalytic hydrogen production activity. MnPS nanosheets of 400 nm with Mn vacancies are produced in high yield by NaCl intercalation and subsequent exfoliation in N-methylpyrrolidone (NMP). NCDs with 5 nm are evenly loaded on the surface of MnPS nanosheets of 400 nm via strong chemical interactions of ammonium sulfate salts formed at the interface. The MnPS-NCDs composites exhibit enhanced light absorption at 500-600 nm, reduced charge recombination and notably promoted photocatalytic activity in relative to neat MnPS nanosheets. MnPS-NCDs composite with the NCDs content of 16.5% possessed the highest photocatalytic hydrogen evolution rate of 339.63 μmol·g·h with good cycling stability, which is 9.17 times that of exfoliated MnPS nanosheets. The type-II MnPS-NCDs heterojunction is conducive to the efficient interfacial carrier transport and the significantly improved photocatalytic hydrogen generation activity. Our work confirmed that the non-toxic MnPS could possess photocatalytic performance comparable to CdS, which will be promising to become an attractive visible-light driven photocatalyst in environmental purification and energy applications.