Synergistic effects in iron-copper bimetal doped mesoporous γ-Al2O3 for Fenton-like oxidation of 4-chlorophenol: Structure, composition, electrochemical behaviors and catalytic performance

Abstract

Iron-copper bimetal supported on mesoporous γ-Al₂O₃ with different Fe/Cu ratios was prepared via a modified evaporation-induced self-assembly method and employed to degrade 4-chlorophenol (4-CP) in a Fenton-like process. The X-ray photoelectron spectroscopy, X-ray diffraction spectrum and UV-vis diffuse reflectance spectroscopy results confirmed the co-doping of Fe²⁺/Fe³⁺ and Cu⁺/Cu²⁺ into the lattice of γ-Al₂O₃ through the bonds of AlOFe and AlOCu. With the iron and copper co-doped in γ-Al₂O₃, three-fold oxygen vacancies (V₀) could be achieved compared with that of non-metal catalysts, which was favorable for the reduction of iron and copper species. The 1Fe3Cu-γ-Al₂O₃ with a Fe/Cu mass ratio of 1:3 exhibited the highest activity on Fenton-like degradation of 4-CP due to the synergistic effects of Fe and Cu by facilitating the electron transfer in the recycles of Cu⁺/Cu²⁺ and Fe²⁺/Fe³⁺ based on the results of X-ray photoelectron spectroscopy, cyclic voltammetry and electro paramagnetic resonance analysis. The utilization efficiency of H₂O₂ was as high as 86.0% when 4-CP almost disappeared (i.e., 99.7 percent of 0.78 mM 4-CP) at 240 min and pH 7.0, additionally, their dechlorination and TOC removal efficiencies were 92.0% and 81.6%, respectively. The catalyst also displayed a good performance after 5th cycles. Furthermore, a possible mechanism for activation of OH on the catalyst surface was also proposed.

Keywords: Cyclic voltammetry; Fenton-like process; Iron-copper bimetallic catalyst; Oxygen vacancy; Synergistic effects.