The boosted and inactivated mechanism of photocatalytic hydrogen evolution from pure water over CoP modified phosphorus doped MnxCd1-xS

Currently, most photocatalysts achieve photocatalytic hydrogen evolution reaction by adding trapping agent, therefore, it is necessary for photocatalysts to achieve photocatalytic hydrogen production under pure water conditions. In this paper, a novel CoP-modified phosphorus-doped MnxCd1-xS (PCOMCS) was synthesized with a significant enhancement of hydrogen production performance in pure water. The samples are characterized by XRD, TEM, DRS, PL, LSV, Mott-Schottky, etc. Research demonstrate that 0.2-PCOMCS has a suitable energy band structure, better separation of photo-induced charges, strong reducibility and low overpotential. When it was applied for splitting pure water to H2, compared with MnxCd1-xS, its hydrogen production rate is increased by approximately 33.48 times, but its steady ability is weak, by measuring the XPS of fresh and used 0.2-PCOMCS, it was found that in the hydrogen production reaction, holes oxidise the CoP and P, decreasing the amount of CoP and the role of phosphorization, resulting that its unstable photocatalytic hydrogen ability from pure water. Then, this phenomenon could be resolved through adding holes trapping agent. Hence, the current work dose not only provide an effective photocatalyst with splitting pure water, but also gives reasonable explanation for inactivating mechanism of photocatalytic hydrogen evolution from pure water.