Promoting charge transfer through oxygen vacancies in ultrathin g-C3N4 to achieve efficient photocatalytic degradation of ciprofloxacin

OVs-UCN was synthesized by oxygen pre-doping and N 2 calcination. • OVs accelerated charge separation and interfacial transfer. • CIP removal reached nearly 99% within 60 min in the PMS/Vis system. • 1 O 2 -dominated non-radical oxidation governed CIP degradation. • OVs-UCN showed real-water applicability and reduced effluent toxicity. Developing green and pollution-free high-performance photocatalysts remains the key to achieving efficient pollutant degradation. In the study, we developed an oxygen pre-doping followed by calcination induced nitrogen elimination strategy to synthesize oxygen-vacancies ultrathin g-C 3 N 4 (OVs-UCN). The tunable layered structure substantially shortens the migration pathway of electrons from the interior in the catalyst to its surface. Importantly, construction of OVs effectively enhances visible-light absorption and modulates the band structure for promoting the photogenerated carriers. Experimental results demonstrate that OVs-UCN removes nearly 99% of ciprofloxacin (CIP) within 60 min, exhibiting significantly superior photocatalytic activity compared with unmodified g-C 3 N 4 . Quenching experiments reveal that CIP degradation is dominated by the synergistic effects of singlet oxygen, holes, and superoxide radical. Moreover, OVs-UCN retains excellent applicability across a wide pH range and in various real-water matrices. This work provides new perspectives for the rational design of heterogeneous photocatalysts and emphasizes the practical promise of vacancy modification strategy for antibiotic wastewater remediation. Download: Download high-res image (133KB) Download: Download full-size image