Tailoring the three-phase microenvironment surface to induce carbon nitride oxide generating ·O2– with 100% selectivity for ultrafast photodegradation tetracycline under visible light

Abstract

The reactive oxygen species (ROS) contribute to photodegrading tetracycline (TC), which determines the overall efficiency of photocatalysts. Superoxide radical (·O2–) is one of the excellent ROS for photodegrading TC by carbon nitride. However, achieving hierarchical carbon nitride with efficient, stabile, and selective production of ·O2– via O2 photoreduction is a great challenge. Herein, a carbon nitride oxide nest (CNON6) with carbon/nitrogen vacancies (C-v, N-v) and oxygen substitution (O-s) was prepared via tailoring surface microenvironment. The CNON6 can photodegrade 82% of TC within 2 min under visible light, and the pseudo-first-order kinetic constant is 1.22 min−1, 24-fold higher than that of CN. The superior photoactivity is attributed to a unique surface microenvironment, which N-v increased photoelectric conversion efficiency, C-v enhanced O2 adsorption and O-s induced ·O2– evolution with ∼ 100% selectivity. Moreover, PVDF membrane-supported CNON6 (11.33 cm2, 0.88 mg/cm2) can completely remove TC from wastewater at a rate of 2.62 mg/h in a simulated industrial continuous flow cell. The cost-effectiveness assessment was $6.36/kg/h, implying the CNON6/PVDF has a bright application prospect in wastewater treatment. This work developed a surface microenvironment tailor strategy to design photocatalysts for efficient degradation of TC.