Magnetic yolk-shell structure of ZnFe2O4 nanoparticles for enhanced visible light photo-Fenton degradation towards antibiotics and mechanism study

Constructing yolk-shell structure is a promising strategy for creating much more active sites and enhancing relative light absorption. Yolk-shell ZnFe2O4 has been well used in the areas of electrocatalysis, sensor, etc., but no corresponding application in photo-Fenton reaction. In this work, yolk-shell ZnFe2O4 was firstly employed as photo-Fenton catalyst to investigate its advantage for antibiotics degradation. Interestingly, the yolk-shell ZnFe2O4 showed much improved photo-Fenton catalytic performance with magnetic recycling property, which is 5 times and 23 times higher than the ZnFe2O4 normal particles and alpha-Fe2O3, respectively, for degradation of contaminants under visible light irradiation. The superiority was mainly attributed to its relatively large surface area and much enhanced light absorption as well as effective charge separation, induced by unique yolk-shell structure. Besides, from the practical application view, the effect of reaction conditions, co-existing cations and anions were systematically investigated for the tetracycline (TC) photo-Fenton degradation. The TC degradation intermediate products were analyzed by HPLC-MS and a possible degradation pathway was proposed to illustrate the mechanism of TC degradation. The as-employed yolk-shell structure of ZnFe2O4 in this work probably provides a new method for designing high efficiency of photo-Fenton catalyst towards the decontamination of refractory pollutants in aqueous solution.