Magnetic core-shell carbon microspheres (CMSs)@ZnFe2O4/Ag3PO4 composite with enhanced photocatalytic activity and stability under visible light irradiation

Novel magnetic core-shell visible light responsive carbon microspheres (CMSs)@ZnFe2O4/Ag3PO4 composite photocatalyst with different mass ratios have been successfully synthesized through the solvothermal and in situ precipitation methods for the first time. The characteristics of the as-prepared materials were systematically determined by the XRD, XPS, SEM, FESEM-EDS, UV-vis DRS, VSM, and PL etc.; the results indicated that all of the composites showed good crystallinity and strong absorbance both in the UV and visible light regions. Moreover, a heterojunction structure was formed between the ZnFe2O4 and Ag3PO4. The photo catalytic performance of the composite was evaluated for 2,4-dichlorophenol (2,4-DCP) degradation, and enhanced photo catalytic activity and stability were achieved. When the mass ratio of CMSs, ZnFe2O4, and Ag3PO4 in the composite was 2:1:3, the apparent photodegradation rate constant of 2,4-DCP was 0.0184 mm(-1), which was 7.36 times that of ZnFe2O4, 2.45 times that of Ag3PO4, and 4 times that of CMSs@ZnFe2O4 (mass ratio = 2:1). And after four times recycling, the photodegradation efficiency of 2,4-DCP over the CMS5@ZnFe2O4/Ag3PO4 (mass ratio = 2:1:3) can even reach approximately 89%. The investigation of the photocatalytic mechanism suggested that both the effective separation of the photoinduced electron-hole pairs and the active free radicals formed in the special core-shell interface contributed to the superior photocatalytic performance of the composite. (C) 2015 Elsevier B.V. All rights reserved.