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.

通过燃烧化石燃料产生的有毒气体，例如氮氧化物（NOX）和硫氧化物（SOX），会产生烟雾和酸雨。将这些有害污染物转换为更安全的副产品是一个重大而重要的挑战。在该项目中，通过化学划分的化学催化计划的资金，南加州大学的斯蒂芬·克罗宁博士正在研究血浆驱动的催化，以消除这些污染物。催化剂是加速化学反应而不会消耗的物质。催化剂需要能量运行，研究团队正在研究平原（低温，荧光灯中的发光气体是等离子体的一个例子）来传递该能量。这项工作中获得的基本知识可以改进的系统来修复这些有害的污染物。用于研究等离子体驱动的化学反应的专门技术也可以应用于其他广泛的催化反应。克罗宁博士正在积极从事宣传活动，以他的研究为基础，以促进学生参与科学，技术，工程和数学（STEM）学科。这些活动包括针对高中科学老师的研讨会，旨在改善有前途的高中生的教育，并鼓励他们对STEM职业的兴趣。随着化学级化学催化计划的资金，南加州大学的克罗宁博士正在研究使用原位减弱总反射（ATR） - ftir光谱的关键反应中间体的振动特征。在这里，使用纳秒高电压脉冲跨含有纳米颗粒的基质（例如PT，AG，AU），使用纳秒高电压脉冲来生成热电子，低温瞬态脉冲等离子体。这些纳米颗粒可在血浆的产生中提供高达1000倍的增强，该等离子体位于纳米颗粒表面，在该表面最有用，在纳米颗粒的表面上。这种瞬时等离子体的低温性对于维持这些细腻的纳米颗粒的结构完整性至关重要，并且使用常规射频（RF）等离子体不可能。 Cronin博士及其小组探索了几种测试反应系统，包括NO，NO2和SO2修复。尽管这些反应都使用基于等离子体的过程证明了这些反应，但这些血浆辅助反应的详细化学途径尚不清楚。尽管其他形式的光谱法在等离子体（例如LIF光谱法）上进行了广泛进行，但ATR-FTIR是一种固有的表面敏感光谱法，通过阐明关键中间物种的阐明，为血浆驱动的催化反应机制提供了新的见解。通过使用几种不同类型的金属纳米颗粒表面（例如Cu，Ni，Pt）鉴定表面中间体，Cronin博士及其小组在气体和液相中测试了几种假设的化学途径。例如，一个假设是SO2修复是由OH自由基驱动的（即SO2→HSO3→H2SO4），可以由等离子体产生。 Cronin博士积极从事专注于女性学生招募STEM领域和高中学生研究实习的STEM外展计划，以支持该项目的广泛影响。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和广泛影响的评估来通过评估来支持的珍贵的支​​持。

项目成果

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
• 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.

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
• 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.

Enhanced Plasma Generation from Metal Nanostructures via Photoexcited Hot Electrons

• DOI: 10.1021/acs.jpcc.1c00765
• 发表时间: 2021-03
• 期刊: Journal of Physical Chemistry C
• 影响因子: 3.7
• 作者: Bofan Zhao;Indu Aravind;Sisi Yang;Y. Wang;Ruoxi Li;Boxin Zhang;Yi Wang;J. Dawlaty;S. Cronin

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
• 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
• 通讯作者: Singleton, Dan