In situ fabrication of Bi2O3/C3N4/TiO2@C photocatalysts for visible-light photodegradation of sulfamethoxazole in water

Abstract

Developing visible-light-driven photocatalysts with high charge separation and transfer efficiency to degrade organic pollutants in wastewater remains a major issue. In this work, quaternary Bi2O3/C3N4/TiO2@C (BCTC) hybrids were successfully fabricated by hydrothermal and calcination two-step method using Bi(NO3)3·5H2O, C3N4, and Ti3C2 as precursors. The optimized BCTC hybrids with the dosage of 1 g L−1 (BCTC-2%) exhibited high photocatalytic activity, degrading 100% sulfamethoxazole (SMZ, 5 mg L−1) within 100 min under visible light irradiation. Moreover, the photocatalytic degradation rate of SMZ by the quaternary junction was found to be 5.12-, 2.87-, and 1.35-fold higher as compared with Bi2O3/C3N4, C3N4/TiO2@C, and Bi2O3/TiO2@C junctions, respectively. The enhanced photocatalytic performance of BCTC hybrids could be attributed to the formation of a double Z-scheme photocatalytic system and the photosensitization of Bi2O3 and C3N4. The photogenerated hole (h+) was the primary reactive species that degraded SMZ. The plausible intermediates during the photocatalytic degradation of SMZ were identified by high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry and the degradation pathway was postulated. Importantly, BCTC-2% had a good photocatalytic activity for degrading SMZ in natural water samples, indicating the high potential of BCTC hybrids for wastewater treatment applications.