Collaborative Research: Developing Novel Surface Immobilized Photocatalysts Using Functionalized C60

众所周知，C60 （buckminsterfullerene）及其一些功能化衍生物可以光化学生成单线态氧和超氧化物等活性氧。这种将光能转化为氧化能的方法在光催化有机合成和光动力治疗中得到了广泛的研究和应用。虽然富勒烯基光催化也是一种很有前途的可持续水处理方法，但由于原始的C60实际上是不可润湿的，因此很难使C60接近水中的目标污染物，因此这种水相应用受到了限制。即使C60是水溶性的（例如，通过功能衍生化），也很难防止C60释放到产品水中并循环利用以长期使用。提出的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，用于水和废水的处理和再利用。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支撑材料上来实现这一目标。具体的研究目标包括：1)开发新的和改进现有的方法来固定C60和选择功能化的C60到支撑材料表面；2)量化它们的光化学反应活性，主要与1O2的产生有关，作为载体底物和水化学的函数；3)评价这些新型光敏剂对选定有机污染物的降解和对具有代表性的微生物的失活。他们假设：1)C60及其衍生物与聚合物表面的化学附着是可以实现的，而C60的笼状结构产生的1O2的光化学活性没有明显的损失；2)由于C60的化学稳定性，C60基催化剂在长时间使用后，光催化活性的降低最小；3)通过共价键固定可以减少催化剂对环境的释放，提高回收利用率。这些假设的有效性为开发基于c60的创新光催化工艺奠定了基础。这是一个由两家机构合作的项目，汇集了光活性纳米材料合成、基础光化学和光催化剂在有机污染物氧化降解和微生物灭活方面的应用。他们将首先采用选定的均质和固定化形式的四烷基和六烷基- c60加合物，其中包括羧基、羟基和胺基。具体任务包括：1)水溶性功能化C60、C60（或衍生化C60）包被微珠和C60（或衍生化C60）结合聚合物的合成；2)利用湿化学方法、电子自旋共振（ESR）捕获技术和激光闪光光解（LFP）技术对这些材料的光化学性质进行了表征，重点研究了其产生1O2的动力学和机理；3)光催化氧化有机污染物及典型微生物（细菌和病毒）灭活的动力学和机理研究。这是将富勒烯光催化技术应用于环境工程的首次尝试之一。他们的动机是C60的独特性质，包括1)特殊的光催化活性，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，便于回收再利用，有利于富勒烯基光催化的进一步应用研究。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在附着和杀菌机制上如何变化的基本理解也将对生态毒理学风险评估具有重要意义。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，从而开发更可持续的水管理方法。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，该催化剂只需要阳光就可以进行水的修复和再利用。研究结果将在出版物中广泛传播，并纳入本科和研究生课程。他们还将在一个合格的专业人才短缺的新兴领域培养学生。这些学生将获得纳米化学、光化学和环境工程应用的跨学科和协作经验。

0933219/0932872 Alvarez/Kim It 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.