Enhanced photo-Fenton degradation of dyes under visible light with recyclable γ-Fe2O3/CQDs: Catalyst preparation, performance and mechanism insight
A low band gap and visible light-responsive heterogeneous Photo-Fenton catalyst of γ-Fe 2 O 3 /CQDs micron composite was prepared under the one-pot hydrothermal method. The Photo-Fenton degradation of γ-Fe 2 O 3 /CQDs towards dye solution of rhodamine B(RhB), methyl blue (MB), and methyl orange (MO) was studied comparatively with α-Fe 2 O 3 . The γ-Fe 2 O 3 /CQDs exhibited remarkable catalytic performance for various dyes and with a first-order rate ( k ) of 14 times higher than that of initial α-Fe 2 O 3 with a low concentration of H 2 O 2 of 0.049 mmol . L −1 and a wider pH range of 3.1–7.1. The microstructure of the compounds was observed by XRD, SEM, TEM, FT-IR, and XPS characterization results suggested that the γ-Fe 2 O 3 /CQDs nanocomposite was formed through the stable Fe–O–C bonds, thus, the band gap decreased, and it is more favorable for the distance of holes and electrons. The free radical trapping experiment and EPR analysis indicated that •OH and 1 O 2 were the major active species during the typical photo-Fenton reaction. What's more, the γ-Fe 2 O 3 /CQDs also exhibited good stability and magnetic properties. DFT conclusion shows that the mechanism of the potential determination step (PDS) on α-Fe 2 O 3 (220) is the cleavage of H 2 O 2 with an energy barrier of only 0.08 eV, which is 0.54 eV lower than that of OH* on γ-Fe 2 O 3 (220). Thus it can be deemed that γ-Fe 2 O 3 /CQDs perform much higher catalytic activity for the dissociation of H 2 O 2 than α-Fe 2 O 3 . This work gives a feasible and economical countermeasure of visible light Photo-Fenton dispose of dye wastewater with a recyclable magnetic γ-Fe 2 O 3 /CQDs micron catalyst.
危险品化学品经营许可证（带存储）