Simultaneously manipulating excitons and charge carriers in g-C3N4 with abundant cyano groups and N vacancies for photocatalytic molecular oxygen activation

Abstract

Photocatalytic molecular oxygen (O₂) activation mediated by excitons and charge carriers plays a crucial role in environmental remediation. Herein, N-vacancy rich g-C₃N₄ catalyst modified with cyano groups was successfully fabricated through a dual-alkali etching strategy, which exhibited a remarkable O₂ activation under visible light. Experimental and theoretical calculations indicate that N vacancy and cyano group (−C≡N) synergistically enhance the oxygen adsorption ability and greatly boost the production of abundant •O₂⁻ by charge-transfer-mediated O₂ activation. Meanwhile, the introduction of more N vacancies can be able to accelerate the energy transfer pathway to improve ¹O₂ generation. Benefiting from the remarkable yield of reactive oxygen species, dual-alkali etched g-C₃N₄ showed efficient and robust photocatalytic degradation efficiency and broad environmental adaptability toward tetracycline hydrochloride, and the intermediate products are highly harmless. This study provides a novel idea for efficient solar energy utilization toward wastewater restoration by simultaneously utilizing charge transfer and energy transfer.