Facile synthesis of excellent Fe3O4@starch-derived carbon Photo-Fenton catalyst for tetracycline degradation: Rapid Fe3+/Fe2+ circulation under visible light condition

Photoinduction is widely used to accelerate the Fe3+/Fe2+ circulation in Fe3+/H2O2 Fenton oxidation, however, the remained challenges in developing a facile, economical, and efficient synthetic methodology for the preparation of high-performance Fe-based Photo-Fenton catalyst and inevitably forming iron sludge limit its applications. Herein, starch-derived carbon (SC) encapsulated Fe3O4 (Fe3O4@SC) magnetic nanocomposites are synthesized by mechanical activation treatment combined with high-temperature pyrolysis method using cassava starch as the carbon source. The photoelectrochemical properties of Fe3O4@SC are regulated by COFe bonds and oxygen vacancies in Fe3O4@SC, as well as graphitization of SC, which effectively accelerate the Fe3+/Fe2+ circulation in Fe3O4@SC + H2O2 system under visible light, thus Fe3O4@SC shows excellent catalytic performance and superior stability for the degradation of tetracycline hydrochloride, and the initiation rate constant is 2.4 times higher than that in dark. Moreover, quenching experiments and electron spin resonance results confirm that OH, O2−, and h+ (OH plays a critical role) are generated in the catalytic system of Fe3O4@SC + H2O2 + visible light. This work provides new insights into a green and facile approach for the synthesis of Photo-Fenton catalysts, providing new avenue for the acceleration of Fe3+/Fe2+ cycle under visible light-driven Fenton process.