Carbon-based nanocomposites for sensing and catalysis

非技术综述：碳基电子纳米复合材料提供了新的机会，通过启用传感器和改进工艺来改善环境，这些工艺支撑着我们日常生活中使用的材料。利用这一潜力需要深入了解这些材料的反应性，以及创造具有新功能的复合材料的新方法。化学家们对溶液中小分子在均匀环境中的反应性有很深的了解。在材料研究部固体与材料化学计划和化学部催化计划的支持下，这项研究试图将小分子的已知精确度扩展到具有更复杂结构和固态组织的碳基纳米材料。将均相反应性概念转化为催化和传感是通过建立将结构附着到碳纳米材料或围绕碳纳米材料组装结构的新方法来完成的。例如，当活性结合金属的材料是组装的组合物的一部分时，碳基纳米材料可以支撑金属催化剂。麻省理工学院的研究人员开发了按需传递电子的新方法，以更有效和更有选择性的过程驱动反应。例如，在催化中，许多情况下需要铂等稀有金属。在能源转换技术所需的催化方面尤其如此。这项研究创造了支持纳米材料，允许与数量少得多的这些有价值的材料进行卓越的反应。这一努力还支持教育机会，通过麻省理工学院和少数族裔服务机构之间的交流计划，使STEM劳动力多样化，并在研究和商业生涯中激励新一代科学家。技术概述：在材料研究部固态和材料化学项目和化学部催化项目的支持下，本研究试图以石墨烯、碳纳米管(CNTs)、金属纳米颗粒和多孔聚合物为原料创建多组分功能材料体系。它利用新的方法对石墨烯表面和多孔聚合物中的受限空腔进行共价功能化，以生产成分可控的高活性小金属纳米颗粒(直径5 nm)。碳纳米管侧壁的共价修饰是一种将分子催化物种硬连接到导电元件上并产生高催化活性的方法，这种方法将扩展到不对称电催化的产生。在析氧反应中生成的亲电金属氧代中间体用于与烯烃的电化学环氧化反应，而手性碳纳米管催化剂用于制备光学活性的环氧化物。研究人员对碳纳米管和包裹了含有金属结合配体的多孔聚苯醚S(PAE)的碳纳米管进行了共价功能化，这使得他们能够研究这种导电载体中Ni(0)对芳基卤化物的还原偶联作用。开发新的PAE合成方法开辟了可能性的范围，聚合物中可以包含多种金属结合配体。首席研究员和他的团队还研究了是否可以使用含有PAE的多孔性配体将单个金属中心仅传递给每个NP，而其余的组成包含一种或多种其他富含地球上的金属。探索了多元素NP组成，以创建燃料电池相关反应的催化剂，包括乙醇氧化、氢氧化和氧气还原，以及新的耐化学性传感器。研究了具有集成染料的多孔PAE作为光氧化还原催化体系，特别是确定不对称的PAE口袋是否能产生手性产物。除了推进基础材料化学和潜在地生产新的商业相关技术外，这项研究还支持教育机会，以使劳动力多样化，并在研究和商业生涯中激励新一代科学家。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Summary: Carbon-based electronic nanocomposites offer new opportunities to improve the environment by enabling sensors and improving processes that underpin the materials used in our day-to-day existence. Harnessing this potential requires deep understanding of the reactivity of these materials and new methods to create composite materials with novel functionalities. Chemists have a great understanding of the reactivity of small molecules in solution in a homogenous environment. With support from the Solid State and Materials Chemistry program in the Division of Materials Research and the Catalysis program in the Division of Chemistry, this research seeks to extend the known precision of small molecules to carbon-based nanomaterials, which have much more complex structures and solid-state organizations. Translating homogenous reactivity concepts for catalysis and sensing is accomplished by building on new methods for attaching structures to or assembling structures around carbon nanomaterials. For example, carbon-based nanomaterials can support metal catalysts when materials that actively bind the metals are part of the assembled compositions. Researchers at the Massachusetts Institute of Technology develop new methods that deliver electrons on demand to drive reactions in more efficient and selective processes. For example, in many cases in catalysis, rare metals such as platinum are needed. This is particularly true in catalysis needed for energy conversion technologies. This research creates supporting nanomaterials that allow for superior reactivity with much smaller quantities of these valuable materials. This effort also supports educational opportunities to diversify the STEM workforce through an exchange program between Massachusetts Institute of Technology and minority serving institutions, and to inspire new generations of scientists in both research and business careers. Technical Summary: With support from the Solid State and Materials Chemistry program in the Division of Materials Research and the Catalysis program in the Division of Chemistry, this research seeks to create multi-component functional materials systems from graphene, carbon nanotubes (CNTs), metal nanoparticles, and porous polymers. It leverages new methods for the covalent functionalization of graphene surfaces and confined cavities in porous polymers to produce highly active small ( 5 nm diameter) metal nanoparticles of controlled composition. Covalent modification of the sidewalls of carbon nanotubes is used as a method to “hard wire” molecular catalytic species to a conductive element and produce high catalytic activity and this approach will be expanded to the generation of asymmetric electrocatalysis. The electrophilic metal-oxo intermediates generated in the oxygen evolution reaction is used to react with alkenes for electrochemical epoxidation and chiral CNT-catalysts are employed to generate optically active epoxides. The researchers covalently functionalize carbon nanotubes and carbon nanotubes coated with porous poly(phenylene ether)s (PAEs) that contain metal binding ligands, which allows them to investigate reductive coupling of aryl-halides by Ni(0) in such conducting supports. Developing new synthetic methods for PAE opens up the scope of possibilities and a diversity of metal binding ligands can be included in the polymer. The principal investigator and his team also study whether porous ligands containing PAEs could be used to deliver only a single metal center to each NP with the balance of the composition containing one or more other earth abundant metals. Multi-elemental NP compositions are explored to create catalysts for fuel cell relevant reactions, including ethanol oxidation, hydrogen oxidation, and oxygen reduction as well as new chemiresistive sensors. Porous PAEs with integrated dyes are investigated as photoredox catalytic systems, in particular to determine if asymmetric PAE pockets can produce chiral products. In addition to advancing fundamental materials chemistry and potentially producing new commercially relevant technologies, this research also supports educational opportunities to diversify the workforce and inspire new generations of scientists in both research and business careers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.