Enhanced photocatalytic degradation of tetracycline by BiOCl/ZnPc Z-type heterojunction under visible-light irradiation: Promoting singlet oxygen generation

Singlet oxygen ( 1 O 2 ) exhibits superior effectiveness in degrading electron-rich organic pollutants. Herein, we propose a method to modulate 1 O 2 generation by solvothermal construction of bismuth oxychloride/zinc phthalocyanine (BiOCl/ZnPc) heterojunction system. This approach broadens the photoresponse range of BiOCl, strengthens the internal electric field (IEF) between the interfaces, and significantly enhanced the photocatalytic activity of the heterojunction system. The efficiency of the photocatalytic degradation process was evaluated using chlortetracycline hydrochloride (CTC) as a model emerging contaminant. The CTC removal rate using BiOCl/ZnPc (97.94 % in 120 min) was 1.33 times and 17.53 times those of BiOCl (73.47 % in 120 min) and ZnPc, respectively. Electron spin resonance and radical quenching tests revealed that singlet oxygen ( 1 O 2 ) and superoxide radicals (·O 2 − ) played a role in photocatalytic oxidation. The presence of 1 O 2 in the BiOCl/ZnPc heterojunction system enhanced the photocatalytic efficiency of the electron-rich organic compounds such as CTC. This study provides new ideas for heterojunction enhancement to strengthen the efficiency of charge transfer-enhanced generation of 1 O 2 and efficient degradation of electron-rich organic pollutants in water.