【作者】 王凯；

【导师】 余晓皎；

【作者基本信息】 西安理工大学 ， 环境科学与工程， 2025， 博士

【摘要】 抗生素在工农业及医疗等领域的广泛使用使得其不可避免地进入地表水、地下水及海洋中。尽管水体中抗生素浓度较低,但难以自然衰减,可能诱发耐药基因和细菌增殖,威胁生态安全。光催化技术为此提供绿色解决方案,它能将抗生素分子分解为低毒甚至无毒的小分子物质。二维(2D)BixOyBr光催化剂具有合适带隙和丰富活性位点,但对可见光响应范围窄,光生载流子复合率高。本论文针对2D BxOyBr存在的问题,拟通过构建异质结和形成缺陷提升其载流子分离效率。通过对五种抗生素的降解研究,分析BixOyBr基异质结的催化活性,阐明界面电荷迁移机制,评估催化剂稳定性与中间产物生态毒性。主要研究内容及结果如下:(1)SrTiO3/BiOBr异质结的制备及对诺氟沙星和土霉素降解研究。利用微波水热法合成零维/二维(0D/2D)SrTiO3/BiOBr 光催化剂,与 BiOBr 相比,SrTi3/BiOBr(3S-B)的吸收边界保持在445 nm,但阻抗由39.5 kΩ降低到18.1 kΩ,瞬态光电流(i-t)强度由2.4 μA/cm2提高到4.8 μA/cm2。3S-B对诺氟沙星(NOR)和土霉素(OTC)的降解率分别为77.4%和93.5%,较BiOBr提升1.1倍和1.7倍。基于能带结构和密度泛函理论(DFT)证实光催化活性提升得益于0D/2D界面协同功函数匹配的Z型异质结构加速光诱导电荷载流子的产生和迁移。根据DFT预测了 OTC的可能活性位点,采用气相色谱-质谱联用仪(GC-MS)获得了 12种中间产物。通过毒性评估软件工具(T.E.S.T)可知所有中间产物对黑头呆鱼的LC50值均增加,且相比于OTC溶液,降解液对金黄色葡萄球菌的抑菌带宽度由38.8 mm降低到23.0 mm,中间产物毒性显著降低。(2)Cu2O/BiOBr宽可见光响应异质结的制备及对诺氟沙星和磺胺甲噁唑降解研究。鉴于SrTiO3/BiOBr异质结的弱可见光吸收能力,采用微波水热法合成0D/2D Cu2O/BiOBr光催化剂。与BiOBr相比,Cu2O/BiOBr(5C-B)催化剂的光吸收边界由445 nm提高到645 nm。5C-B光催化剂对NOR和磺胺甲噁唑(SMZ)的降解率分别为84.6%和90.7%,是BiOBr的1.4和1.3倍。光催化性能提高在于Cu2O引入拓宽了异质结的可见吸收范围,并且Z型电子转移机制赋予了催化剂强氧化还原能力。基于HPLC-MS测定了 SMZ经过异恶唑开环反应、羟基化反应和苯胺氧化分解的10种中间产物。采用T.E.S.T分析可知,大多数中间产物对大型水蚤和黑头呆鱼的LC50值均增加,且经过6天培育,绿豆在SMZ降解液中的培育长度为14.0 cm,接近于去离子水的17.0 cm,证实中间产物毒性减弱。(3)SrTiO3/BiOBr/Cu2O双通道电子转移异质结的制备及对诺氟沙星和磺胺嘧啶降解研究。针对二元体系单通道电子转移体系空间限制效应,三元异质结的双通道设计可有效降低载流子复合几率。采用微波水热法制备0D/2D/0D SrTiO3/BiOBr/Cu2O三元催化剂,与 SrTiO3/BiOBr相比,SrTiO3/BiOBr/Cu2O(SBC-5)三元光催化剂的阻抗由 18.5 kΩ降低到2.1 kΩ,i-t强度由4.5 μA/cm2提高到9.9 μA/cm2。SBC-5对NOR的降解率为95.4%,对应的降解速率常数(k)为0.0916 min-1,分别是SrTiO3、BiOBr和SrTiO3/BiOBr的3.6、4.1和2.2倍。SBC-5对磺胺嘧啶(SDZ)的降解率为94.7%,是SrTiO3/BiOBr的1.4倍。光催化性能增强源于Cu2O引入拓宽可见光响应范围、0D/2D/0D界面提供了更多反应位点,双通道载流子传输路径降低界面阻抗的协同作用。基于DFT测定了 SDZ可能活性位点,利用HPLC-MS获得12种中间产物。通过T.E.S.T分析可知,随着光照时间延长,最终中间产物对黑头呆鱼的LC50值均增加,且绿豆在SDZ降解液中经过6天培育长度达到16.0 cm,接近于去离子水的18.0 cm,证实降解液低毒性。(4)富Bi协同氧空位策略增强SrTiO3/Bi3O4Br异质结对诺氟沙星和金霉素降解研究。为继续提高BiOBr基异质结的催化活性并解决三元结构合成工艺繁琐的局限性,通过富Bi协同OVs策略进行工艺优化。采用微波水热法构建0D/2D SrTiO3/Bi3O4Br-OVs催化剂,与BiOBr相比,Bi3O4Br-OVs禁带宽度由2.76 eV减小到2.44 eV。与Bi3O4Br-OVs相比,SrTiO3/Bi3O4Br-OVs(9S-BOB)催化剂的阻抗由35.1 kΩ降低到9.1 kΩ,i-t强度由2.2 μA/cm2提高到5.2 μA/cm2。9S-BOB对NOR的降解率为93.6%,对应k值达到了0.0964 min-1,分别是 SrTiO3 和 Bi3O4Br-OVs 的 5.7 和 2.7 倍。9S-BOB 对金霉素(CTC)降解率达到了 92.9%,是Bi3O4Br-OVs的1.6倍。优异的光催化活性取决于富Bi协同OVs策略降低了催化剂禁带宽度,搭载0D/2D结构Z型电子转移机制可有效优化载流子传输效率。根据DFT计算对CTC的活性位点进行识别,采用GC-MS测定了 12种中间产物。使用T.E.S.T分析可知所有中间产物对黑头呆鱼和大型水蚤的LC50值均增加,且金黄色葡萄球菌降解溶液中培养48 h获得的菌落数与在去离子水中培养获得的菌落数量相当,产物的生物毒性风险被有效控制。更多还原

【Abstract】 The widespread application of antibiotics in manufacturing,agriculture,and healthcare industries inevitably leads to their presence in surface water,groundwater,and marine environments.Despite the relatively low concentrations detected in aquatic systems,antibiotics are resistant to natural degradation,potentially promoting the proliferation of drug-resistant genes and bacteria,posing a significant threat to ecological security.Photocatalytic technology provides an environmentally friendly approach to address this issue by decomposing antibiotic molecules into harmless substances such as CO2 and H2O.As a key component of photocatalytic systems,the two-dimensional(2D)BixOyBr photocatalyst exhibits an appropriate bandgap and abundant active sites;however,it suffers from limited visible-light responsiveness and a high rate of photogenerated carrier recombination.This study focuses on addressing the core challenges associated with 2D BixOyBr materials and aims to enhance their carrier separation efficiency through heterojunction construction and defect engineering.By investigating the degradation of five antibiotics,the catalytic activity of BixOyBr-based heterojunctions was evaluated,the interfacial charge migration mechanism was elucidated,and the stability of the catalyst as well as the ecotoxicity of intermediate products were systematically assessed.The primary research contents and findings are summarized as follows:(1)Preparation of SrTiO3/BiOBr heterojunctions and investigation into the degradation of norfloxacin and oxytetracycline.A zero-dimensional/two-dimensional(0D/2D)SrTiO3/BiOBr photocatalyst was synthesized via a microwave-hydrothermal method.Compared with BiOBr,the absorption boundary of SrTiO3/BiOBr(3S-B)remains at 445 nm,but the impedance decreases from 39.5 kΩ to 18.1 kΩ,and the transient photocurrent(i-t)intensity increases from 2.4 μA/cm2 to 4.8μA/cm2.The degradation efficiencies of 3S-B for norfloxacin(NOR)and oxytetracycline(OTC)reached 77.4%and 93.5%,respectively,representing 1.1-fold and 1.7fold improvements over BiOBr.Band structure analysis and density functional theory(DFT)calculations confirmed that the enhanced photocatalytic activity originated from the Z-scheme heterojunction formed at the 0D/2D interface with synergistic work-function matching,which facilitated the generation and migration of photoinduced charge carriers.DFT simulations predicted the potential active sites of OTC,and 12 intermediates were identified via Gas chromatography-mass spectrometry(GC-MS).Toxicity evaluation using the Toxicity Estimation Software Tool(T.E.S.T)revealed increased LC50 values of all intermediates toward the fathead minnow.Furthermore,compared to the OTC solution,the inhibition zone width of the degradation solution against Staphylococcus aureus has decreased from 38.8 to 23.0 mm,indicating a significant reduction in the toxicity of the intermediates.(2)Preparation of Cu2O/BiOBr wide visible light-responsive heterojunctions and study on the degradation of norfloxacin and sulfamethoxazole.To address the weak visible light absorption of SrTiO3/BiOBr heterojunctions,a 0D/2D Cu2O/BiOBr photocatalyst was synthesized via a microwave-hydrothermal method.Compared with pristine BiOBr,the Cu2O/BiOBr composite(5C-B)exhibited a significantly extended optical absorption edge from 445 nm to 640 nm.The degradation efficiencies of 5C-B for NOR and sulfamethoxazole(SMZ)reached 84.6%and 90.7%,respectively,demonstrating 1.4-fold and 1.3-fold enhancements over BiOBr.The improved photocatalytic performance was attributed to the expanded visible-light absorption range enabled by Cu2O incorporation and the robust redox capacity conferred by the Z-scheme electron transfer mechanism.Ten intermediates derived from SMZ degradation were identified via HPLC-MS,involving isoxazole ring-opening reactions,hydroxylation,and aniline oxidation and decomposition.T.E.S.T revealed increased LC50 values for most intermediates toward Daphnia magna and fathead minnow.Additionally,mung beans cultivated in SMZ degradation solutions achieved a growth length of 14.0 cm after 6 days,approaching the 17.0 cm observed in deionized water,further confirming the mitigated toxicity of the intermediates.(3)Preparation of SrTiO3/BiOBr/Cu2O dual-channel electron transfer heterojunction and investigation of norfloxacin and sulfadiazine degradation.To address the spatial confinement effect limiting electron transfer in binary heterojunctions,a ternary heterojunction with dualchannel charge transfer pathways was designed to suppress carrier recombination.A 0D/2D/0D SrTiO3/BiOBr/Cu2O ternary catalyst(SBC-5)was synthesized via microwave-hydrothermal method.Compared with the SrTiO3/BiOBr,the impedance of the SrTiO3/BiOBr/Cu2O(SBC-5)ternary photocatalyst decreased from 18.5 to 2.1 kΩ,while the intensity of i-t increased from 4.5 to 9.9 μA/cm2.The degradation efficiency of SBC-5 for NOR reached 95.4%,with a rate constant(k)of 0.0916 min-1—3.6-,4.1-,and 2.2-fold higher than SrTiO3,BiOBr,and SrTiO3/BiOBr,respectively.For sulfadiazine(SDZ),SBC-5 achieved 94.7%degradation efficiency,1.4 times that of SrTiO3/BiOBr.The enhanced activity originated from synergistic effects:Cu2O incorporation broadened visible-light absorption,the 0D/2D/0D architecture provided abundant reactive sites,and dual-channel charge transfer minimized interfacial resistance.DFT simulations identified potential active sites of SDZ,while HPLC-MS revealed 12 intermediates.Toxicity assessment via T.E.S.T demonstrated increasing LC50 values of final intermediates toward fathead minnow.Mung beans cultivated in SDZ degradation solutions attained a growth length of 16.0 cm after 6 days,approaching 18.0 cm in deionized water,confirming the low ecological risk of treated solutions.(4)Study on enhancing the degradation of norfloxacin and chlortetracycline by SrTiO3/Bi3O4Br heterojunction via a Bi-rich synergistic oxygen vacancy strategy.To enhance the catalytic activity of BiOBr-based heterojunctions while addressing the complexity of ternary structure synthesis,a Bi-rich strategy synergized with oxygen vacancies(OVs)was employed for process optimization.A 0D/2D SrTiO3/Bi3O4Br-OVs catalyst(9S-BOB)was constructed via microwave-hydrothermal synthesis.Compared to BiOBr,Bi3O4Br-OVs exhibited a narrowed bandgap(2.44 eV vs.2.76 eV).Compared to Bi3O4Br-OVs,the impedance of the 9S-BOB catalyst decreased significantly from 35.1 to 9.1 kΩ,while the i-t strength increased from 2.2 to 5.2 μA/cm2.The degradation efficiency of NOR using 9S-BOB was 93.6%,with the corresponding rate constant(k)reaching 0.0964 min-1,which is 5.7 and 2.7 times higher than that of SrTiO3 and Bi3O4Br-OVs,respectively.Additionally,the degradation efficiency of chlortetracycline(CTC)by 9S-BOB reached 92.9%,representing a 1.6-fold increase compared to Bi3O4Br-OVs.The superior performance stems from the Bi-rich OVs strategy narrowing the bandgap and the 0D/2D Z-scheme heterojunction optimizing charge carrier separation efficiency.DFT simulations identified active sites of CTC,while GC-MS detected 12 intermediates.Toxicity assessment via T.E.S.T revealed increased LC50 values of all intermediates toward fathead minnow and Daphnia magna.Moreover,Staphylococcus aureus colony counts in CTC degradation solutions after 48 h cultivation matched those in deionized water,confirming minimal biotoxicity risks of the degradation products.更多还原