Visible light induced efficient activation of persulfate by a carbon quantum dots (CQDs) modified γ-Fe2O3 catalyst

In this study, a carbon quantum dots modified maghemite catalyst (CQDs@γ-Fe2O3) has been synthesized by a one-step solvothermal method for efficient persulfate (PDS) activation under visible light irradiation. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS) characterization indicated that the formation of heterojunction structure between CQDs and γ-Fe2O3 effectively reduced the catalyst band gap (Eg), favoring the separation rate of electrons and holes, leading to remarkable efficient sulfamethoxazole (SMX) degradation as compared to the dark-CQDs@γ-Fe2O3/PDS and vis-γ-Fe2O3/PDS systems. The evolution of dissolved irons also demonstrated that CQDs could accelerate the in-situ reduction of surface-bounded Fe3+. Electron paramagnetic resonance (EPR) and radical scavenging experiments demonstrated that both •OH and SO4•− were generated in the reaction system, while •OH was relatively more dominant than SO4•− for SMX degradation. Finally, the reaction mechanism in the vis-CQDs@γ-Fe2O3/PDS system was proposed involving an effective and accelerated heterogeneous-homogeneous iron cycle. CQDs would enrich the photo-generated electrons from γ-Fe2O3, causing efficient interfacial generation of surface-bond Fe2+ and reduction of adsorbed Fe3+. This visible light induced iron cycle would eventually lead to effective activation of PDS as well as the efficient degradation of SMX.Graphical ...
Source: Chinese Chemical Letters - Category: Chemistry Source Type: research