• Accepted manuscript •

### S-Scheme-Enhanced PMS Activation for Rapidly Degrading Tetracycline Using CuWO4−x/Bi12O17Cl2 Heterostructures

Ruyao Chen1, Jiazeng Xia2, Yigang Chen2, Haifeng Shi1,3

1. 1 School of Science, Jiangnan University, Wuxi 214122, Jiangsu Province, China;
2 Department of General Surgery, Wuxi No. 2 People's Hospital, Affiliated Wuxi Clinical College of Nantong University, Wuxi 214002, Jiangsu Province, China;
3 National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
• Received:2022-09-09 Revised:2022-09-23 Accepted:2022-09-30 Published:2022-10-08
• Contact: 史海峰;陈义钢Haifeng Shi;Yigang Chen E-mail:hfshi@jiangnan.edu.cn;wuxichen2512@njmu.edu.cn
• Supported by:
This work was supported by the National Natural Science Foundation of China (22136002, 22172064), the Special Fund Project of Jiangsu Province for Scientific and Technological Innovation in Carbon Peaking and Carbon Neutrality, China (BK20220023), the Project of Wuxi Science and Technology Development Fund, China (Y20212004), and National Laboratory of Solid State Microstructures, Nanjing University, China (M34047). Prof. Haifeng Shi was indebted to the financial support from the Qing Lan Project of Jiangsu Province, China.

Abstract: The peroxymonosulfate (PMS) activation reaction based on photocatalysts has been widely employed for the removal of tetracycline (TC) and other antibiotics. The photocatalyst comprising CuWO4 decorated with oxygen vacancies has attracted research attention owing to its narrow band gap, favorable oxidation ability, and good charge transfer efficiency. A single-component photocatalyst can influence the PMS activation efficiency due to the rapid recombination between photogenerated electron and hole pairs. Herein, oxygen vacancy-decorated CuWO4−x/Bi12O17Cl2 (CovB) photocatalysts were fabricated, and enabled an enhancement in the PMS activation efficiency for TC removal under visible-light irradiation. The crystalline structures and optical properties of CovB were measured by field-emission scanning electron microscopy, transmission electron microscopy, and UV-visible diffuse reflectance spectroscopy. Characterization of the O 1s bond by electron paramagnetic resonance (EPR) analyses and X-ray photoelectron spectra (XPS) showed that the oxygen vacancies were successfully introduced into the composites. CovB-30 (mass ratio of CuWO4−x to Bi12O17Cl2 was 3 : 7) achieved a TC removal rate of 94.74% in 30 min in the PMS activation system. The degradation efficiencies of CovB-30 were 2.67 and 2.21 times higher than those of CuWO4 and Bi12O17Cl2, respectively. The enhanced TC elimination performance can be ascribed to the synergetic effect between photocatalysis and the PMS activation reaction, which were promoted by the S-scheme heterojunction. The S-scheme heterojunction structure could maintain an excellent redox ability under light irradiation and generate an internal electric field, which possessed the ability to prevent the recombination of photogenerated carriers. The photoluminescence (PL) measurements and time-resolved photoluminescence (TRPL) spectra confirmed that the formation of the S-scheme heterojunction effectively increased the migration rates and separation efficiency of photogenerated hole and electron pairs, facilitating the activation of PMS for TC removal. CovB-30 retained the ability to eliminate TC in a wide pH range of 3.0–11.0 and different inorganic anion systems. The XPS profiles of fresh and used samples indicated that the Cu2+/Cu+ redox cycle and oxygen vacancies both participated in the activation of PMS. XPS analysis and experimental capture results illustrated that the charge transfer mechanism of the CovB composite followed that of an S-scheme heterojunction photocatalyst. CovB-30 maintained excellent PMS activation ability over a wide pH range of 3.0–11.0. This paper discusses the possible TC degradation pathways in the PMS activation system on the basis of the generated intermediates. Quenching experiments were conducted, and demonstrated that SO4•−/∙OH/∙O2/h+/1O2 served as the reactive species in TC removal. The CovB-30 composite possessed remarkable photocatalytic activity after five consecutive cycles, illustrating that it could be utilized for practical antibiotic degradation. This work proposes a promising method of introducing oxygen vacancies into an S-scheme photocatalyst for efficient PMS activation.

MSC2000:

• O643