EAGER: Novel Catalyst Design Using Hierarchical Hybrid Materials

通过将纳米材料与更大的多孔支架进行量身定制的集成而设计的新型催化剂催化剂是一种使能技术，对水、能源、化工和制药等关键工业部门至关重要。任何固体催化剂的有效性在很大程度上取决于表面反应中心的可用性。纳米材料(尺寸在1-100纳米范围内)在这方面提供了显著的优势，因为与传统材料相比，它们提供了非常高的单位质量表面积。然而，纳米催化剂通常以松散的粉末或胶体形式部署，很容易分散到环境中，造成严重的健康和环境风险。这个向莱特州立大学的Sharmila Mukhop adhyay教授颁发的热切的奖项项目的目标是探索能否通过结合纳米材料的优势和坚固固体的结构完整性来解决这一困境。在自然生物表面，如肠道和支气管壁，通过“分层”和“混合”结构，在紧凑的空间中实现了极高水平的相互作用，其中较大的支架提供机械支持，逐渐变小的专用附件提供额外的功能特性。该项目将探索是否以及如何将相同的概念应用于催化剂设计，从多孔固体支架开始，并使用可控的强附着纳米级催化材料，如碳纳米管、氧化物涂层纳米管和金属纳米颗粒来增强它们。回报可能非常高，因为它将使创新的表面驱动设备的创造成为可能，包括催化剂、传感器和储能元件。该项目的另一个好处是将纳米技术与催化和环境可持续性联系起来的教育组成部分。这个项目的所有参与者都参与了学生辅导和K-12教育模块的开发。将从该项目中受益的外展计划包括为弱势学生提供大学前课程和为STEM教师举办训练营。该项目的目标是深入了解分层杂化材料的加工和性能，在这种材料中，不同维度的纳米级组件的良好分布被固定在更大的多孔支架上。设想的支架支撑材料是泡沫或碳纤维织物，其比表面积通过控制地附着像地毯一样的碳纳米管阵列而增加几个数量级。这些纳米管可以被覆盖有氧化物层，以增加表面润湿性和/或改善催化剂-载体相互作用。最后，这些纳米管增强的支架表面将使用催化剂纳米颗粒如钯进行功能化。合成的材料将用于降解一种模型水基污染物三氯乙烯(TCE)，三氯乙烯在工业上被广泛使用，并以其在地下水中的毒性和持久性而闻名。这个项目将回答与表面活性设备相关的三个非常基本的问题：(I)是否有可能以足够的控制将多个纳米催化剂连接到单个坚固的固体上？(2)综合混合材料将保留或改进每个组成部分的好处？如果是这样的话，集成固体与其组分以及与传统催化剂颗粒和粉末相比情况如何？(Iii)这些构筑物是否适合长期使用？这些问题的答案可以为将先进的纳米催化剂集成到更大的固体设备中提供基础。

Novel catalyst design by tailored integration of nanomaterials with larger porous scaffoldsCatalysts are an enabling technology critical to key industrial sectors such as water, energy, chemicals, and pharmaceuticals. The effectiveness of any solid catalyst strongly depends upon the availability of surface reactive sites. Nanomaterials (that have dimensions in 1-100 nm range) provide significant advantages in this regard because they offer exceptionally higher surface area per unit mass compared to conventional materials. However, nanocatalysts are generally deployed as loose powders or colloids that can easily disperse into the surroundings, posing serious health and environmental risks. The goal of this EAGER award project made to Professor Sharmila Mukhopadhyay at Wright State University is to explore if this dilemma can be resolved by combining the advantages of nanomaterials with the structural integrity of robust solids. In natural biological surfaces such as intestinal and bronchial linings, an extremely high level of interaction in a compact space is enabled through "hierarchical" and "hybrid" architectures, in which larger scaffolds provide mechanical support and progressively smaller specialized attachments offer additional functional properties. This project will explore if and how the same concept can be adapted to catalyst design, starting with porous solid scaffolds and enhancing them with controlled sequence of strongly adhered nano-scale catalytic materials such as carbon nanotubes, oxide coated nanotubes, and metal nanoparticles. The payoff can be very high, since it will enable creation of innovative surface-driven devices including catalysts, sensors and energy storage components. Another benefit from this project will be educational components relating nanotechnology with catalysis and environmental sustainability. All participants in this project are involved in student mentoring as well as development of K-12 educational modules. Outreach programs that will benefit from this project include pre-college offerings for disadvantaged students and training camps for STEM Teachers.The goal of this project is to provide in-depth understanding of processing and properties of hierarchical hybrid materials, in which well-tailored distribution of nanoscale components of varying dimensions are anchored on larger porous scaffolds. Scaffold support materials envisioned are foams or fabric of carbon, whose specific surface areas are increased by several orders of magnitude through controlled attachment of carpet-like arrays of carbon nanotubes. These nanotubes may be coated with oxide layers for increased surface wettability and/or improved catalyst-support interactions. Finally these nanotube-enhanced scaffold surfaces will be functionalized with catalyst nanoparticles such as palladium. The materials synthesized will be used to degrade a model water-borne pollutant, trichloroethene (TCE), which is widely used by industry and known for its toxicity and persistence in ground-water. This project will answer three very basic questions relevant to surface-active devices: (i) Is it possible to attach multiple nano-catalysts to a single robust solid with sufficient control? (ii) Would the integrated hybrid material retain or improve the benefits of each component? If so, how does the integrated solid compare with its components and with conventional catalyst pellets and powders? (iii) Are these structures suitable for prolonged use? The answers to these questions can provide the groundwork for integrating advanced nanocatalysts into larger solid devices.