In Situ Characterization of a Single Catalytic Nanoparticle

目前，对催化活性的不了解限制了新催化剂的发现、优化和商业化应用的效率。这个项目描述了一个集中的努力来测量单个催化纳米颗粒的化学活性。通过单独测量颗粒，可以精确地确定组成、大小和底物支持的结果，从而揭示使某些催化剂系统比其他催化剂系统更有效的机制。这项研究得到了新的实验技术的支持，该技术将单个催化颗粒集成到可操作的三端纳米级电路中。加州大学欧文分校的PI研究小组专门研究基于碳纳米管的电路的制造，表征和化学修饰，并且已经证明了构建电阻由单个铂，钯或镍颗粒主导的电路的能力。目前的专业技术包括在原始碳纳米管中产生点缺陷，调整该缺陷的化学性质，然后在该位置成核并生长一个粒子。该项目的目标是利用这些纳米电路在现场实时监测催化剂颗粒的化学活性。这种电路对它们的附着物非常敏感，并且已经在液体和气体中证明了单个Pd和Ni颗粒的化学读数。该项目将探索发生在各种金属、金属间化合物和金属氧化物颗粒表面的催化和电化学反应。这个研究项目的智力价值在于集中精力定量区分非常相似的催化系统。例如，一个目标是区分不同大小的Pd颗粒的相对活性。另一个目的是比较羟基端和羧基端作为催化剂载体的碳。第三个目标是制备双粒子系统，以研究粒子间距的重要性。这些研究都直接解决了普通系综测量的主要缺点，并有可能为催化研究的新突破提供有效的途径。该项目还将通过加速高活性催化剂的发现过程，产生重大而广泛的影响。如果成功，这一建议将直接解决过程控制和提高催化剂系统的可预测性。该项目还将为加州大学欧文分校的研究生培训提供多个机会，并通过PI广泛的教学和外展活动得到加强。

0729630Collins, Philip A poor understanding of catalytic activity currently limits the efficiency with which new catalysts can be discovered, optimized, and implemented in commercial applications. This project describes a focused effort to measure the chemical activity of single catalytic nanoparticles. By measuring particles singly, the consequences of composition, size, and substrate support can be precisely determined, in order to uncover mechanisms which make some catalyst systems more effective than others. The research is underpinned by new experimental techniques in which single catalytic particles are integrated into operational, three-terminal nanoscale circuits. The PI's research group at UC Irvine specializes in the fabrication, characterization, and chemical modification of circuits based on carbon nanotubes, and has demonstrated the ability to build circuits in which the resistance is dominated by a single platinum, palladium, or nickel particle. Current expertise includes the ability to produce a point defect in a pristine carbon nanotube, tailor the chemistry of that defect, and then nucleate and grow one particle at that site. The project goal is to employ these nanocircuits to monitor the chemical activity of catalyst particles in situ and in real time. The circuits are exquisitely sensitive to their attachments, and chemical readout from single Pd and Ni particles has already been demonstrated in liquids and gases. The project will explore both catalytic and electrochemical reactions occurring at the surfaces of various metal, intermetallic, and metal oxide particles. The intellectual merit of this research program is a focused effort to quantitatively differentiate between very similar catalytic systems. For example, one objective is to distinguish the relative activity of differently-sized Pd particles. Another aim is to compare hydroxyl- and carboxylterminated carbons as catalyst supports. A third objective is to prepare dual-particle systems in order to study the importance of interparticle spacing. Each of these investigations directly addresses major shortcomings in common ensemble measurements and potentially provides an efficient route to new breakthroughs in catalysis research. This project will also have significant broader impact by accelerating the discovery process of high activity catalysts. If successful, this proposal will directly address process control and improve the predictability of catalyst systems. The project will also generate multiple opportunities for graduate training at UC Irvine and be reinforced by the PI's extensive teaching and outreach activities.