Bi2Zr2O7 nanoparticles synthesized by soft-templated sol-gel methods for visible-light-driven catalytic degradation of tetracycline.

Tetracycline (TC), an antibiotic, is persistent in nature and frequently detected in water and sediments. Visible-light-driven photocatalyst for TC degradation is a promising environmental-friendly technology. Bi2Zr2O7, an effective photocatalyst, but no studies on its photodegradation of TC could be found in literature. In this study, Bi2Zr2O7 was synthesized by three soft templated sol-gel methods. Three synthesized Bi2Zr2O7 catalysts have different structures, morphologies and band gaps. The Bi2Zr2O7 nanoparticles synthesized with citric acid as the template (BZO-3) had a larger specific surface area (30.7 m2/g) and a narrower band gap (2.39 eV), and exhibited a better performance for TC degradation under visible light with an efficiency of up to 81.3%. They also exhibited good stability and reusability in recycled experiments. A reaction mechanism of TC degradation by these photocatalyst was proposed. The enhanced photocatalytic performance was mainly due to photogenerated holes of reactive species and TC was mainly degraded on the surface of the photocatalyst. Pathways of TC photodegradation were derived from the result of analyses of the reaction intermediates. In conclusion, Bi2Zr2O7 nanoparticles were found effective as photocatalyst for TC photodegradation by visible light.