Dual step-scheme heterojunction with full-visible-light-harvesting towards synergistic persulfate activation for...

The occurrence of micropollutants in aquatic media raises great concern because of their biological toxicity and persistence. Herein, visible-light-driven photocatalyst titanium dioxide/graphitic carbon nitride/triiron tetraoxide (TiO_2-x/g-C₃N₄/Fe₃O₄, TCNF) with oxygen vacancies (O_v) was prepared via a facile hydrothermal-calcination method. The complementary visible-light co-absorption among semiconductors enhances light-harvesting efficiency. The built-in electric field formed during Fermi level alignment drives photoinduced electron transfer to improve charge separation across the interfaces. The increased light-harvesting and favorable energy band bending significantly enhance the photocatalytic performance. Therefore, TCNF_-5-500/persulfate system could effectively photodegrade bis-phenol A within 20 min under visible-light irradiation. Moreover, the superior durability, non-selective oxidation, adaptability, and eco-friendliness of the system were confirmed by different reaction conditions and biotoxicity assessment. Furthermore, the photodegradation reaction mechanism was presented according to the major reactive oxygen species produced in the system. Thus, this study constructed a dual step-scheme heterojunction by tuning visible-light absorption and energy band structure to increase the charge transfer efficiency and photogenerated carrier lifetime, which has great potential for environmental remediation using visible photocatalysis.