Z-scheme photo-Fenton system for efficiency synchronous oxidation of organic contaminants and reduction of metal ions

Abstract The applications of traditional photo-Fenton reaction are mainly limited by the low photo generated electron concentration, resulting in the low Fe3+/Fe2+ conversion efficiency and low concentration of reactive oxygen specious (ROS). In this study, a mesoporous TiO2 single crystal decorated by platinum (Pt) nanoparticles and molybdenum disulfide (MoS2) hybrid Z-scheme system (Pt-MSCs@MoS2) is successfully synthesized for efficiency synchronous REDOX. The construction of Z-scheme composite leads to the consumption of photo-generated hole (h+) and prolongs the lifetime of the electrons (e−) of MoS2, so as to ensure that the MoS2 is exposed with Mo4+ active sites and exhibits high efficiency for Fe2+/Fe3+ cycling. The high Fe2+/ Fe3+ ratio of Z-scheme photo-Fenton system is conducive to the decomposition of hydrogen peroxide (H2O2) to produce more ·OH. High concentration of photo-generated e− with high reduction potential is conducive to the reduction and recovery of various metal ions, such as Cr6+, Ag+, Cu+ and Ni+. Therefore, the Z-scheme photo-Fenton system shows strong synchronous REDOX performance for removal of different emerging organic contaminants and recovery of different metal ions. The reasonable mechanism of Z-scheme photo-Fenton system and oxidation pathway of carbamazepine (CBZ) were investigated by experimental analysis and molecular orbital calculation. The toxicities of CBZ and its oxidation intermediates in Z-scheme photo-Fenton systems were compared by Toxicity Estimation Software (T.E.S.T.) based on quantitative structure-activity relationship (QSAR). This Z-scheme provides a high efficiency synchronous REDOX strategy for wastewater treatment.