CAREER: Modulation of Kinetic Dispersion at the Single Molecule Level on Individual Catalytic Nanoparticles

职业：在单分子水平上调节单个催化纳米颗粒的动力学分散

• 批准号: 1254527
• 负责人: Robert Rioux
• 金额: $ 42.5万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1254527&HistoricalAwards=false
• 关键词: CAREER; Modulation; Kinetic; Dispersion; Single

Technical/Scientific MeritThe impact of catalysis on the economy and technology of industrialized countries is impossible to overstate. It is surprising that our current knowledge of catalyst design that leads to a catalyst capable of desired product formation with minimal environmental impact is often quite rudimentary. Heterogeneous catalysis is extremely complex and the dynamics at the catalyst surface sites during catalytic turnover influences the kinetic outcome of the reaction. Studying nanoparticle catalysts a single particle at a time with single turnover resolution will improve our molecular level understanding of the origins of kinetic dispersion, and will provide insights on how to utilize this information to design catalysts with optimized activity and selectivity. Robert M. Rioux of The Pennsylvania State University will provide this level of study under a NSF Faculty Early Career Development (CAREER) Program Award. Rioux analogizes the situation to that in biological systems. Single molecule measurements have revolutionized how biologists think about structure and function since it was revealed structure is dynamic rather static with changes in structure occurring while functioning. In heterogeneous catalyst systems, experimental studies have also provided direct evidence that surface atoms responsible for catalytic turnover are dynamic, rather than static. However, measured reactivity is due to an ensemble of surface atoms, and structural dynamics have not been coupled with reactivity measurements. Understanding how dynamic structural changes (fluxionality) couple to function is critical to the design of next generation catalysts since this is direct insight into the catalytic entity responsible for catalytic turnover. Rioux will investigate structure-function relationships utilizing single nanoparticle methods with single turnover resolution coupled with characterization of the catalytic solid-liquid interface with novel calorimetric methods and chemical titration. Experimental studies utilizing pro-fluorescent molecules which convert to fluorophores will be utilized to examine the relationship between dynamic structural changes ? whether these changes are associated with the nanoparticle itself or the primary solvation layer -- and single molecule turnover trajectories. Catalyst variables such as particle size and their subsequent modification with adsorbates of varying affinity and chemical character will be examined. The rate of reaction is influenced drastically by temperature and the influence of temperature-dependent fluxionality on the catalytic processes will be evaluated. Distribution of kinetic and thermodynamic parameters associated with proposed rate expressions will be assessed at the single molecule level and compared with ensemble equivalents. This work will additionally examine the spatial dependence of simultaneous turnover on activity and selectivity using a non-fluorescent reactant that produces two products with different emission characteristics. The relationship between reaction selectivity and location on the catalytic nanoparticle will be assessed with correlative microscopy.Broader ImpactsThe results of the proposed research will provide the catalysis/nanoparticle community with unambiguous structure-function relationships regarding the kinetics and dynamics of catalytic turnover. The fundamental insight into catalytic processes gained from single nanoparticle measurements should enable more efficient catalyst design by providing a dynamic, rather than static picture of the influence of structure on function.Educational activities supported by this NSF CAREER proposal focus on the development of a first year seminar (FYS) to attract and retain particularly undergraduate female students in the chemical engineering major. The newly-developed FYS will integrate the PI?s current involvement in AIChE ChemE car project and provide a ?hands-on? mentored experience for freshmen/sophomore female students. The FYS will include a component of outreach to the commonwealth campuses of Penn. State, where female (and male) students do not have the opportunity to participate in a chemical engineering themed FYS. The PI along with his graduate students will travel to the commonwealth campuses for on-site, ?hands-on? demonstrations.

催化对工业化国家的经济和技术的影响是不可能夸大的。令人惊讶的是，我们目前的催化剂设计知识，导致催化剂能够形成所需的产品，具有最小的环境影响往往是相当初级的。 多相催化是极其复杂的，在催化剂表面的网站在催化剂周转的动力学影响的反应动力学结果。 研究纳米粒子催化剂，一次一个粒子，单周转分辨率将提高我们的动力学分散的起源分子水平的理解，并将提供关于如何利用这些信息来设计具有优化的活性和选择性的催化剂的见解。 Robert M.宾夕法尼亚州立大学的Rioux将根据NSF教师早期职业发展（CAREER）计划奖提供这种水平的学习。Rioux将这种情况与生物系统中的情况进行了类比。单分子测量已经彻底改变了生物学家对结构和功能的看法，因为它揭示了结构是动态的，而不是静态的，结构的变化发生在功能的同时。在多相催化剂体系中，实验研究也提供了直接证据，表明负责催化转换的表面原子是动态的，而不是静态的。 然而，测量的反应性是由于表面原子的合奏，结构动力学还没有与反应性测量耦合。 了解动态结构变化（流动性）如何与功能耦合对下一代催化剂的设计至关重要，因为这是对负责催化转换的催化实体的直接洞察。 Rioux将研究结构-功能关系，利用单纳米颗粒方法，单周转率分辨率，再加上催化固液界面的表征，新的量热方法和化学滴定。 利用亲荧光分子转换成荧光团的实验研究将被用来研究动态结构变化之间的关系？这些变化是否与纳米颗粒本身或主要溶剂化层有关-以及单分子周转轨迹。 催化剂的变量，如颗粒大小和随后的修改与不同的亲和力和化学性质的吸附物将被检查。 反应速率受温度的影响很大，并将评估温度依赖性对催化过程的影响。 与建议的速率表达式相关的动力学和热力学参数的分布将在单分子水平上进行评估，并与系综当量进行比较。 这项工作还将研究使用非荧光反应物，产生两种产品具有不同的发射特性的同时营业额的活性和选择性的空间依赖性。 反应的选择性和位置之间的关系的催化纳米粒子将进行评估与相关microscopic. broaderimpactsThe结果提出的研究将提供明确的结构-功能关系的催化/纳米粒子社区的动力学和动力学的催化营业额。 从单个纳米颗粒测量获得的催化过程的基本见解，应使更有效的催化剂设计，通过提供一个动态的，而不是静态的图片的结构对function.Educational活动的影响支持的NSF CAREER建议侧重于第一年的研讨会（FYS）的发展，特别是吸引和留住本科女生在化学工程专业。 新开发的FYS将整合PI？目前参与AIChE ChemE汽车项目并提供？亲自动手为大一/大二女生提供辅导经验。 FYS将包括对宾夕法尼亚州英联邦校园的宣传。国家，女（和男）学生没有机会参加化学工程为主题的FYS。 PI沿着他的研究生将前往英联邦校园现场，？亲自动手示威