Decorating Zn_0.5Cd_0.5S with C,N Co-Doped CoP: An Efficient Dual-Functional Photocatalyst for H₂ Evolution and...

Photocatalytic H₂ evolution and biomass-derived alcohol oxidation is a cooperative way for improving the utilization of photogenerated charge carriers. Herein, a highly efficient photocatalyst was fabricated by decorating Zn_0.5Cd_0.5S with a C,N codoped CoP polyhedron (referred to as CoP, derived from ZIF-67), and then it was used for H₂ evolution and 5-hydroxymethylfurfural (HMF) oxidation. For the optimized sample (20% CoP/Zn_0.5Cd_0.5S), the generated H₂ rate is significantly enhanced from that of the HMF aqueous solution with 2,5-diformylfuran (DFF) as a concomitant product, about 31.7 times higher than the pristine Zn_0.5Cd_0.5S under visible light irradiation. The separation of photoexcited electrons (e^-) and holes (h⁺) in the process was promoted, as both e^- and h⁺ were involved in the desired conversions. From the results of density functional theory (DFT) calculations and in situ XPS spectra, the utilization of e^- was further improved as a spontaneous transfer from Zn_0.5Cd_0.5S to CoP occurred due to the p-n heterojunction formed between Zn_0.5Cd_0.5S (n type) and CoP (p type). This work provides an efficient method to separate the photoinduced charge carriers and a new way for H₂ evolution accompanied by transformation of HMF to DFF.