N vacancies and OH/C=O co-modified g-C3N4 photoactivated peroxymonosulfate for the degradation of tetracycline: Synergistic promotion effect between excitons and carriers

Activation of peroxymonosulfate (PMS) to generate reactive oxygen species (ROS) for pollutant degradation via metal-free photocatalysts is an important green wastewater treatment and remediation method, but the pathway for generating ROS via exciton effects in catalysts is often overlooked. In this study, OH/C=O co-modified N-defective rod-shaped carbon nitride (Nv-CN-O) was designed and synthesized by soft template and alkali hydrothermal method. In the Nv-CN-O/PMS/Light system, there was a synergistic degradation of tetracycline (TC) by carriers and excitons, with a degradation rate 2.15 times higher than that of CN/PMS/Light. N vacancies and OH/C=O enhanced the adsorption to PMS, accelerated the charge transfer process, and activated PMS to generate ·O 2 − dominated reactive species. The functional group OH/C=O promoted the production of triplet excitons that through the energy transfer pathway to promote the production of 1 O 2 . Abundant ROS were involved in the TC degradation process, and three possible TC degradation pathways were proposed. Nv-CN-O has strong anti-interference ability in actual water bodies, shows a promoting effect on the degradation of TC, which has practical application potential.