Enhanced photocatalytic performance of spinel ferrite (MFe2O4, M=Zn, Mn, Co, Fe, Ni) catalysts: The correlation between morphology–microstructure and photogenerated charge efficiency

Spinel ferrites have attracted much attention due to their excellent chemical stability and activation properties. However, the effect of the morphology-microstructure on the photogenerated charge efficiency of these composites has rarely been studied. Herein, the relationship between the morphology-microstructure and photogenerated charge efficiency of spinel ferrites was investigated. In this study, spinel ferrites (MFe2O4, M = Zn, Mn, Co, Fe, Ni) were synthesized by a one-step hydrothermal method, and the morphology-microstructure was regulated by adjusting the preparation parameters. According to the results of UV–vis diffuse reflectance spectroscopy and transient photocurrent measurements, photogenerated electrons in smaller particles had higher separation and transfer rates. In addition, high crystallinity was expected to reduce the recombination rate of electron-hole pairs. Further research on the interactions among the preparation conditions was conducted using Box-Behnken design (BBD). The results showed that there were interactions among the preparation parameters and the optimum conditions were pH= 10.14, 13.34 h and 187.12 ℃. Under these conditions, the degradation rate constant of ciprofloxacin was 1.5 times higher than those of the original catalysts. This research provides basic theoretical and technical support for the precise regulation of MFe2O4 synthesis.