Environment-friendly ternary ZnO/ZnFe2O4/TiO2 composite photocatalyst with synergistic enhanced photocatalytic activity under visible-light irradiation

Developing novel environmental-friendly photocatalysts with ideal properties is an endless project, urged by growing demands of advance in high efficiency, energy saving, and environmental remediation. In this work, a novel ternary ZnO/ZnFe2O4/TiO2 composite photocatalyst have been synthesized via a facile synthetic method. Anatase TiO2 particles with average crystallite size of 10.38 nm are thinly coated on the surface of octahedrallike ZnO/ZnFe2O4 nanoparticles. The ternary composite photocatalyst displays stronger transient photocurrent response characteristics, about 3 times larger than that of pristine ZnFe2O4 under visible-light irradiation, indicating excellent photogenerated charge carriers transfer efficiency. Compared with ZnFe2O4 and ZnO/ ZnFe2O4, the ZnO/ZnFe2O4/TiO2 composite photocatalyst have the optimal photocatalytic properties, achieving 96.32% degradation efficiency for methylene blue (MB) aqueous solution after 150 min of visible-light irradiation. More impressive is the stability, after 4 cycles, its photocatalytic activity still no significant decreases. Reactive species trapping tests reveal that not superoxide radicals but hydroxyl radicals and photogenerated holes are highly responsible for the photocatalysis process. The enhancement of photocatalytic activity is ascribed to the synergetic effect of large specific surface area, efficient visible-light absorption, and rapid migration of photogenerated charge carriers. The results disclose the ternary ZnO/ZnFe2O4/TiO2 composite photocatalyst is a suitable photocatalyst candidate for environmental remediation.