CAS: Mechanistic Study of Reaction Intermediates in Nanoparticle-Enhanced Plasma-Assisted Catalysis

CAS：纳米粒子增强等离子体辅助催化反应中间体的机理研究

• 批准号: 1954834
• 负责人: Stephen Cronin
• 金额: $ 31.1万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-15 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1954834&HistoricalAwards=false
• 关键词: CAS; Mechanistic; Study; Reaction; Intermediates

Toxic gases such as nitrogen oxides (NOx) and sulfur oxides (SOx), produced by the burning of fossil fuels, give rise to smog and acid rain. Converting these harmful pollutants to safer by-products is a significant and important challenge. In this project, with funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Stephen Cronin of the University of Southern California is investigating plasma-driven catalysis as a way to eliminate these pollutants. Catalysts are substances that accelerate chemical reactions without themselves being consumed. Catalysts require energy to function, and the research team is investigating plasmas (the low temperature, glowing gas in fluorescent lamps is an example of plasma) to deliver that energy. The fundamental knowledge gained in this work enables improved systems for remediating these harmful pollutants. The specialized techniques used to investigate plasma-driven chemical reactions can also be applied to a wide range of other catalytic reactions. Dr. Cronin is actively engaged in outreach activities that build upon his research to promote engagement of students in science, technology, engineering and mathematics (STEM) disciplines. These activities, which include a workshop for high school science teachers, are directed at improving the education of promising high school students and encouraging their interest in STEM careers. With funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Cronin of the University of Southern California is studying the vibrational signatures of key reaction intermediates using in situ attenuated total reflection (ATR)-FTIR spectroscopy. Here, a hot-electron, low-temperature transient pulsed plasma is generated using nanosecond high voltage pulses across a substrate containing nanoparticles (e.g., Pt, Ag, Au). These nanoparticles provide up to 1000X enhancement in the generation of the plasma, which is localized to the surface of the nanoparticles where it is most useful for catalysis. The low-temperature nature of this transient plasma is crucial to maintaining the structural integrity of these delicate nanoparticles and would not be possible with a conventional radio frequency (RF) plasma. Dr. Cronin and his group explore several test reaction systems, including NO, NO2, and SO2 remediation. While these reactions have all been demonstrated using plasma-based processes, the detailed chemical pathways of these plasma-assisted reactions are not well understood. While other forms of spectroscopy have been performed extensively on plasmas (e.g., LIF spectroscopy), ATR-FTIR is an inherently surface-sensitive spectroscopy that provides new insights into the plasma-driven catalytic reaction mechanisms through the elucidation of key intermediate species. By identifying surface intermediates using several different types of metal nanoparticle surfaces (e.g., Cu, Ni, Pt), Dr. Cronin and his group test several hypothetical chemical pathways in both the gas and liquid phases. For example, one hypothesis is that SO2 remediation is driven by OH radicals (i.e., SO2 → HSO3 → H2SO4), which can be produced by the plasma. Dr. Cronin is actively engaged in STEM outreach programs focused on female student recruitment into the STEM fields and in high school student research internships, in support of the broader impacts of the project.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.

化石燃料燃烧产生的氮氧化物 (NOx) 和硫氧化物 (SOx) 等有毒气体会产生烟雾和酸雨，将这些有害污染物转化为更安全的副产品是一项重大挑战。在化学系化学催化项目的资助下，南加州大学的 Stephen Cronin 博士正在研究等离子体驱动的催化，作为消除这些现象的一种方法。催化剂是一种能够加速化学反应而不被消耗的物质，催化剂需要能量才能发挥作用，研究小组正在研究等离子体（荧光灯中的低温发光气体就是等离子体的一个例子）来传递这种能量。在这项工作中获得的知识可以改进用于修复这些有害污染物的系统，用于研究等离子体驱动的化学反应的专业技术也可以应用于广泛的其他催化反应。以他的研究为基础，促进学生参与科学、技术、工程和数学 (STEM) 学科。这些活动包括为高中科学教师举办的研讨会，旨在改善有前途的高中生的教育并鼓励他们的兴趣。在化学系化学催化项目的资助下，南加州大学的 Cronin 博士正在利用原位衰减全反射 (ATR)-FTIR 光谱研究关键反应中间体的振动特征。使用纳秒高压脉冲在含有纳米颗粒（例如 Pt、Ag、Au）的基底上产生热电子、低温瞬态脉冲等离子体。这些纳米颗粒可将局部等离子体的生成增强高达 1000 倍。这种等离子体瞬变的低温特性对于维持这些精致纳米颗粒的结构完整性至关重要，并且会影响纳米颗粒的表面。 Cronin 博士和他的团队探索了几种测试反应系统，包括 NO、NO2 和 SO2 修复，虽然这些反应均已使用基于等离子体的工艺进行了演示，但详细的化学反应是不可能的。虽然其他形式的光谱学主要在等离子体上进行（例如 LIF 光谱学），但 ATR-FTIR 本质上是一种表面敏感光谱学，它为等离子体驱动的反应提供了新的见解。通过阐明关键中间体物种来研究催化反应机制 通过使用几种不同类型的金属纳米颗粒表面（例如铜、镍、铂）识别表面中间体，克罗宁博士和他的团队测试了气体和液体中的几种假设的化学途径。例如，一种假设是 SO2 修复是由 OH 自由基驱动的（即 SO2 → HSO3 → H2SO4），它可以由 Cronin 博士产生。积极参与 STEM 外展计划，重点关注女学生进入 STEM 领域和高中生研究实习，以支持该项目的更广泛影响。该奖项的法定使命，并通过使用基金会的评估被认为值得支持智力价值和更广泛的影响审查标准。

项目成果

Plasma-enhanced electrostatic precipitation of diesel exhaust particulates using nanosecond high voltage pulse discharge for mobile source emission control

利用纳秒高压脉冲放电对柴油机尾气颗粒物进行等离子体增强静电沉淀，用于移动源排放控制

• DOI: 10.1016/j.scitotenv.2022.158181
• 发表时间: 2022-12
• 期刊: Science of The Total Environment
• 影响因子: 9.8
• 作者: Zhang, Boxin;Aravind, Indu;Yang, Sisi;Weng, Sizhe;Zhao, Bofan;Schroeder, Christi;Schroeder, William;Thomas, Mark;Umstattd, Ryan;Singleton, Dan;et al
• 通讯作者: et al

Au Nanoparticle Enhancement of Plasma-Driven Methane Conversion into Higher Order Hydrocarbons via Hot Electrons

金纳米粒子通过热电子增强等离子体驱动的甲烷转化为高阶碳氢化合物

• DOI: 10.1021/acsanm.0c02912
• 发表时间: 2020-12
• 期刊: ACS Applied Nano Materials
• 影响因子: 5.9
• 作者: Zhao, Bofan;Aravind, Indu;Yang, Sisi;Wang, Yu;Li, Ruoxi;Cronin, Stephen B.
• 通讯作者: Cronin, Stephen B.

CO 2 Reduction to Higher Hydrocarbons by Plasma Discharge in Carbonated Water

通过碳酸水中的等离子体放电将 CO 2 还原为高级烃

• DOI: 10.1021/acsenergylett.1c01666
• 发表时间: 2021-11
• 期刊: ACS Energy Letters
• 影响因子: 22
• 作者: Yang, Sisi;Zhao, Bofan;Aravind, Indu A.;Wang, Yu;Zhang, Boxin;Weng, Sizhe;Cai, Zhi;Li, Ruoxi;Baygi, Ali Zarei;Smith, Adam;et al
• 通讯作者: et al

Enhanced Plasma Generation from Metal Nanostructures via Photoexcited Hot Electrons

通过光激发热电子增强金属纳米结构的等离子体生成

• DOI: 10.1021/acs.jpcc.1c00765
• 发表时间: 2021-04
• 期刊: The Journal of Physical Chemistry C
• 作者: Zhao, Bofan;Aravind, Indu;Yang, Sisi;Wang, Yu;Li, Ruoxi;Zhang, Boxin;Wang, Yi;Dawlaty, Jahan M.;Cronin, Stephen B.
• 通讯作者: Cronin, Stephen B.

Voltage-induced modulation in the charge state of Si-vacancy defects in diamond using high voltage nanosecond pulses

使用高压纳秒脉冲对金刚石中硅空位缺陷的电荷状态进行电压感应调制

• DOI: 10.1063/5.0066537
• 发表时间: 2021-10
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Weng, Sizhe;Coleman, Christopher;Aravind, Indu;Wang, Yu;Zhao, Bofan;Cronin, Stephen B.
• 通讯作者: Cronin, Stephen B.