超临界CO2辅助Ag3PO4量子点/层状镧系氢氧化物多孔纳米线的表界面调控及吸附-可见光催化协同降解抗生素的增效机制

Based on the advantages of Ag3PO4 with wide visible light response range and strong catalytic oxidation capacity, and the defects of easy light corrosion and difficult to recover, the supported photocatalysts of Ag3PO4 quantum dot/layered lanthanide hydroxide porous nanowires will be synthesized by using the supercritical CO2 technology. The synthesized catalyst will be applied to adsorb and visible-light photodegrade antibiotic contaminants. Firstly, the surface and interface properties (active site, specific surface area, light absorption properties, etc.) of the photocatalysts will be controlled by changing the reaction parameters, and the reaction conditions will be optimized by the response surface method. Secondly, the role and contribution of adsorption of the photocatalysts on the antibiotics photodegradation will be studied by a variety of in situ spectral characterization techniques. Moreover, the kinetic model of the adsorption-photocatalytic degradation of antibiotics would be established, and the degradation mechanism would be elucidated by combining with the density functional theory. Thirdly, the efficiency enhanced mechanism of the catalyst will be revealed by analyzing its electron-hole migration rule on the surface/interface and the anti-corrosive properties. And on this basis, the structure-activity relationship of the catalyst will be discussed with the help of catalyst configuration calculation by the density functional theory. The results will provide technical support for the application of Ag3PO4-based photocatalysts in the field of refractory organic pollutants degrading, and also can enrich the catalytic reaction theory of the supported photocatalysts.

基于Ag3PO4可见光响应范围宽、催化氧化能力强的优势，针对其易光腐蚀、难回收的缺陷，拟采用超临界CO2技术辅助合成负载型光催化剂Ag3PO4量子点/层状镧系氢氧化物多孔纳米线，并将其应用于吸附-可见光催化降解抗生素类污染物。通过改变制备反应参数实现光催化剂的表界面性质（活性位、比表面积、光吸收性能等）调控，并利用响应曲面法优化反应条件；通过多种原位光谱表征技术深入研究吸附在抗生素光催化降解过程中的角色和贡献，并结合密度泛函理论（DFT）对降解（中间）产物的全优化计算，构建抗生素的吸附-光催化降解动力学模型，阐明其降解机理；通过分析催化剂表界面电子-空穴迁移规律及抗光腐蚀性，揭示光催化剂的吸附-光催化协同增效机制，并在此基础上，结合DFT对催化剂构型的计算，探讨催化剂的构效关系。研究结果为Ag3PO4基光催化剂在难降解有机污染物领域的应用提供技术支撑，丰富了负载型光催化剂的催化反应理论。

抗生素作为疾病的预防治疗药剂及有机体的生长促进剂，被广泛应用于临床及畜禽和水产养殖等领域，从而造成大量抗生素类废水的排放。而市政污水处理系统对抗生素类物质的去除效果不理想，致使抗生素随出水进入自然环境，从而严重影响人类健康和生态平衡。半导体光催化技术在有机污染物的深度处理中具有高效、节能、反应条件温和、无二次污染等优势，为充分利用自然界太阳光谱中的可见光，具有可见光响应性的催化剂是目前的研究热点。Ag3PO4被认为是可见光响应性催化剂的重大突破，但其必须在有电子牺牲剂的条件下才能表现出极强的催化氧化能力。项目针对Ag3PO4易光腐蚀、难分离回收的缺陷，设计合成负载型光催化剂层状镧系氢氧化物/Ag3PO4、异质结型催化剂La1-xSrxCoO3/Ag3PO4、CuBi2O4/Ag3PO4和CuBi2O4/β-Bi2O3，考察了催化剂制备方法和条件对催化剂物化性质的影响，重点研究了催化剂组成以及各成分之间的协同作用对催化剂催化活性和循环利用性的影响及规律。结果表明：镧系氢氧化物的结构和物化性质受溶剂组成、添加剂等影响较大，且所得的镧系氢氧化物/Ag3PO4负载型催化剂中，得益于Ag3PO4的强可可见光吸收能力、La(OH)xA3-x•yH2O对电子的强转移能力、及La(OH)xA3-x•yH2O的高比表面积对双酚A的强富集能力等，使得复合材料表现出更优异的光催化活性；而对于异质结型催化剂La1-xSrxCoO3/Ag3PO4，锶掺杂使得镧系材料物表面具有更多的氧空位，不仅为催化反应体系提供了更多的活性位点，提高了催化活性，而且提高了电子与空穴的有效分离，减小了催化剂的光腐蚀性；此外，在CuBi2O4/Ag3PO4的光催化体系中着重研究了H2O2、S2O82-和溶液pH对催化活性影响的交互作用，酸性条件有利于催化反应的进行，H2O2的添加对复合材料的性能和抗光腐蚀性均有很大程度提高，而S2O82-的加入虽然能大幅提高催化剂的催化活性，但是却不能抑制Ag3PO4的光腐蚀性。该项目的顺利实施，为Ag3PO4基光催化剂在难降解有机污染物领域的应用提供了理论依据和技术支撑。