CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)梯型异质结增强PMS活化性能用于高效抗生素去除

S-Scheme-Enhanced PMS Activation for Rapidly Degrading Tetracycline Using CuWO_(4−x)/Bi_(12)O_(17)Cl_(2) Heterostructures

利用光催化剂中产生的光生电荷活化过一硫酸盐(PMS)用于抗生素等污染物的去除,由于结合了光催化反应和PMS活化的独特优势,近年来引起了广泛的关注。然而,对于单一光催化剂,严重的光生电子空穴对的复合限制了其活化PMS的效率。于此,本文构建了CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)光催化剂,通过梯型异质结促进电荷分离,实现高效PMS活化。通过X射线衍射仪技术(XRD)、高分辨透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)和紫外-可见漫反射光谱(UVVis)等分析手段对所制备催化剂的形貌和结构进行了详细的表征。另外,通过在可见光照射下降解四环素(TC),系统地研究了CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)的催化活性。结果发现,与CuWO_(4-x)和Bi_(12)O_(17)Cl_(2)相比,CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)表现出了明显增强的四环素降解活性:在加入微量的PMS及可见光照射30分钟后,对四环素的降解效率达到了94.74%。X射线光电子能谱以及捕获实验结果表明,CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)复合材料遵循梯型异质结电荷迁移机制。得益于梯型异质结的构建,CuWO_(4-x)/Bi_(12)O_(17)Cl_(2)光催化剂中电子和空穴的传输与分离效率得到显著提高,同时还能保持复合材料最佳的氧化还原能力。此外,对比反应前后样品的X射线光电子能谱结果,发现铜离子和氧空位也参与PMS活化,这将促进反应中活性自由基的产生,从而进一步提高了TC的降解效率。本研究为合成可高效活化PMS和降解抗生素的梯型异质结光催化剂提供了新的思路。

The peroxymonosulfate(PMS)activation reaction based on photocatalysts has been widely employed for the removal of tetracycline(TC)and other antibiotics.The photocatalyst comprising CuWO_(4) 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 CuWO_(4−x)/Bi_(12)O_(17)Cl_(2)(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 CuWO_(4−x) to Bi_(12)O_(17)Cl_(2) 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 CuWO_(4) and Bi_(12)O_(17)Cl_(2),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 Cu^(2+)/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 SO_(4)•−/∙OH/∙O_(2)^(−)/h^(+)/^(1)O_(2) 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.