Collaborative Research: Developing Novel Surface Immobilized Photocatalysts Using Functionalized C60

0933219/0932872 Alvarez/KM众所周知，C60(巴克明斯特富勒烯)及其一些官能化的衍生物可以光化学方式产生单线态氧和超氧化物等活性氧物种。这种将光能转化为氧化能的过程已被广泛研究并应用于光催化有机合成和光动力治疗。尽管基于富勒烯的光催化也是一种很有前途的可持续水处理方法，但由于原始C60几乎不可湿润，这种水相应用受到了限制，因为很难使C60接触到水中的目标污染物。即使C60是可溶于水的(例如，通过官能化衍生法)，要防止C60释放到产品水中并将其循环使用以延长使用时间也是具有挑战性的。拟议研究的总体目标是克服上述限制，开发环境友好的C60基光催化剂，用于水和废水处理和再利用。他们计划通过共价键将C60的光活性形式固定在易于回收的载体材料上，从而实现这一目标。具体的研究目标包括：1)开发新的和增强现有的方法将C60和选定的官能化C60固定在载体材料表面；2)定量它们的光化学反应活性，主要与载体底物和水化学的函数有关；3)评估这些新型光敏剂对选定有机污染物的降解和对代表性微生物的灭活。他们假设：1)C60和C60衍生物可以化学连接到聚合物表面，而不会因为C60的笼状结构而导致光化学活性的任何损失；2)由于C60的化学稳定性，C60催化剂在长时间使用后光催化活性的下降将是最小的；3)通过共价键合的固定化将使催化剂对环境的释放减少到最低，并提高循环利用率。这些假设的有效性为开发创新的基于C60的光催化过程奠定了基础。这是一个两个机构的合作，汇集了光活性纳米材料合成、基础光化学和光催化剂应用于有机污染物氧化降解和微生物灭活方面的专业知识。他们最初将采用选定的均质和固定化形式的四元和六元C60加合物，带有羧基、羟基和胺部分。具体工作包括：1)合成水溶性官能化的C60、C60(或衍生的C60)包覆的小球和C60(或衍生的C60)结合的聚合物；2)表征这些材料的光化学性质，重点是利用湿化学法、电子自旋共振(ESR)捕获技术和激光闪光光解(LFP)产生1O2的动力学和机理；以及3)对选定的有机污染物的光催化氧化和代表性微生物(细菌和病毒)的灭活进行动力学和机理研究。这是首次尝试将基于富勒烯的光催化应用于环境工程。它们的动机是C60的独特性质，包括1)出众的光催化活性，2)利用可见光进行光激发的能力，以及3)化学稳定性。C60的固定化有利于防止二次污染，有利于回收再利用，这将促进富勒烯基光催化应用的进一步研究。例如，表面固定化C60可用于抗菌表面合成或空气净化。对富勒烯的光催化性能如何随附着和杀菌机制的变化而获得的基本了解也将对生态毒理学风险评估提供重要信息。确保获得廉价和清洁的水源是本世纪最大的全球挑战之一。纳米技术提供了跨越传统基础设施密集型技术的机会，以开发更可持续的水资源管理方法。该项目具有开发安全、易于实施和可重复使用的C60基光催化剂的巨大潜力，只需要阳光就可以进行水的修复和再利用。结果将在出版物中广泛传播，并纳入本科生和研究生课程。他们还将在一个新兴领域培训学生，在这个领域，合格的专业人员短缺。这些学生将在纳米化学、光化学和环境工程的应用方面获得跨学科和协作经验。

0933219/0932872Alvarez/KimIt is well known that C60 (buckminsterfullerene) and some of its functionalized derivatives can photochemically produce reactive oxygen species such as singlet oxygen and superoxide. This conversion of light energy to oxidizing power has been extensively studied and applied for photocatalytic organic synthesis and photodynamic therapy. Although fullerene-based photocatalysis is also a promising sustainable approach for water treatment, such aqueous phase applications have been limited by the difficulty to make C60 accessible to target pollutants in water, since pristine C60 is virtually nonwettable. Even if C60 is rendered water soluble (for example, by functional derivatization), it is challenging to prevent C60 release to product water and recycle it for prolonged use. The overarching objective of the proposed research is to overcome the above limitations and develop environmentally benign C60-based photocatalysts for water and wastewater treatment and reuse. They plan to achieve this goal by immobilizing photoactive form of C60 onto easily recoverable support materials via covalent bonding. Specific research objectives include: 1) developing new and enhancing existing methods to immobilize C60 and selected functionalized C60 onto support material surfaces; 2) quantifying their photochemical reactivity, mainly related to 1O2 production, as a function of support substrate and water chemistry; and 3) evaluating these novel photosensitizers for degradation of selected organic contaminants and inactivation of a representative microorganism. They hypothesize that: 1) chemical attachment of C60 and C60 derivatives to polymeric surface is achievable without any significant loss in photochemical activity for 1O2 production which originates from C60s cage structure; 2) C60 based catalyst will exhibit minimal reduction of photocatalytic activity after prolonged use due to the chemical stability of C60, and 3) immobilization via covalent bonding will minimize catalyst release to environment and enhance recycling. Validity of these hypotheses forms a foundation for developing an innovative C60-based photocatalysis process. This is a two-institution collaboration that brings together expertise in photoactive nanomaterial synthesis, fundamental photochemistry, and photocatalyst application for oxidative degradation of organic contaminants and inactivation of microorganisms. They will initially employ selected homogenized and immobilized forms of tetrakis- and hexakis-C60 adducts with carboxylic, hydroxyl, and amine moieties. Specific tasks include: 1) syntheses of water-soluble functionalized C60, C60(or derivatized C60)-coated beads, and C60 (or derivatized C60)-incorporated polymer; 2) characterization of photochemical properties of these materials with focus on kinetics and mechanisms of 1O2 production using wet-chemical method, electron spin resonance (ESR) trapping technique, and laser flash photolysis (LFP); and 3) kinetics and mechanistic studies on photocatalytic oxidation of selected organic pollutants and inactivation of representative microorganisms (bacteria and virus). This is one of the first attempts to apply fullerene-based photocatalysis in environmental engineering. They are motivated by the unique properties of C60, including 1) exceptional photocatalytic activity, 2) ability to use visible light for photoexcitation, and 3) chemical stability. Immobilization of C60 is conducive to prevention of secondary contamination and facilitating recycle and reuse, which will encourage further research on applications of fullerene-based photocatalysis. For example, surface immobilized C60 could be applied for antibacterial surface synthesis or air purification. Fundamental understanding gained on how the photocatalytic properties of fullerenes change upon attachment and bactericidal mechanisms will also be important to inform ecotoxicological risk assessment. Ensuring access to inexpensive and clean sources of water is one of the greatest global challenges of this century. Nanotechnology offers opportunities to leapfrog over traditional infrastructure-intensive technologies to develop more sustainable approaches for water management. This project has a great potential to develop safe, easy to implement, and reusable C60-based photocatalysts that require only sunlight for water remediation and reuse. Results will be broadly disseminated in publications and integrated into undergraduate and graduate courses. They will also train students in an emerging area where qualified professionals are in short supply. These students will gain interdisciplinary and collaborative experience with applications of nanochemistry, photochemistry and environmental engineering.