Remarkably enhanced visible-light photocatalytic hydrogen evolution and antibiotic degradation over g-C3N4 nanosheets decorated by using nickel phosphide and gold nanoparticles as cocatalysts

In this study, a highly efficient ternary 6.7%Au/Ni2P/g-C3N4 nanocomposite is rationally fabricated through a two-step hydrothermal followed by green photoreduction strategy. The XPS analysis, SEM and HRTEM images reveal that Ni2P and good nanoparticles (AuNPs) are successfully loaded onto the surface of g-C3N4 and heterojunction formed among them. The optimized 6.7%Au/0.5%Ni2P/g-C3N4 demonstrates the highest photocatalytic efficiency towards decomposition of levofloxacin hydrochloride with 88.23% removal rate and hydrogen generation rate of 78.65 μmol·g−1·h−1, in comparison with the binary 0.5%Ni2P/g-C3N4 (76.86%, 47.06 μmol·g−1·h−1) and pristine g-C3N4 (61.26%, 45.61 μmol·g−1·h−1). Notably, this is the first time using Ni2P and AuNPs co-modified g-C3N4-based nanocomposites to evaluate the photocatalytic degradation performance of levofloxacin hydrochloride. The study of the corresponding enhanced mechanism indicates that the dramatically improved photocatalytic performance is originated from the synergistic effects: including (1) the strong optical absorption property of Ni2P and the SPR effect of AuNPs endows the remarkably improved visible-light harvesting for increasing charge carrier production; (2) the co-catalysts of Ni2P and AuNPs play key roles as interfacial electron sinkers and facilitate photogenerated electron-hole pairs separation and migration; (3) the co-integration improves the specific surface area of final product which can provide more active sites for the improvement of photocatalytic performance. Moreover, a plausible degradation pathway for levofloxacin hydrochloride is proposed based on the UPLC-MS analysis. Our work highlights a good example for designing and constructing other highly-efficient g-C3N4-based multicomponent photocatalysts for both solar energy conversion and environmental remediation.