Accessing and Stabilizing Metastable States by Coupling Plasma and Surface Chemistry

通过耦合等离子体和表面化学来访问和稳定亚稳态

• 批准号: 2247498
• 负责人: Casey O'Brien
• 金额: $ 57.66万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247498&HistoricalAwards=false
• 关键词: Accessing; Stabilizing; Metastable; States; Coupling

With support from the Chemical Catalysis program in the Division of Chemistry, Casey O’Brien and William Schneider of the University of Notre Dame are working collaboratively (1) to clarify the mechanisms by which atmospheric pressure plasmas couple with solid surfaces to access and stabilize metastable nitrogen species, and (2) to explore the potential to exploit these metastable states to drive novel reactions. The integration of atmospheric pressure plasmas with heterogeneous catalysts (plasma catalysis) has recently gained considerable attention because of its potential to carry out transformations that are difficult or impossible using conventional thermal catalysis, and in modular units powered by renewable electricity. Realization of this potential would lead to more energy-efficient and environmentally sustainable chemical processes. Nitrogen activation in particular has attracted substantial interest in the plasma catalysis community because of the ability of plasma to activate the strong dinitrogen triple bond. Preliminary work in the O’Brien lab suggests that the types of adsorbed nitrogen species relevant to plasma catalysis may be richer than previously thought. This project focuses on clarifying the nature and reactivity of plasma-generated nitrogen species using spectroscopic techniques developed in the O’Brien lab and computational approaches in the Schneider lab. The theory-informed spectroscopic approach and proof-of-concept catalytic examples will broadly impact both catalysis science and technology. This research will also enhance advanced scientific education through training of graduate students in experimental and computational research, communication, scientific rigor, and the ethical conduct of research.This proposal explores a strategy to access, stabilize, and concentrate metastable intermediates that are thermally inaccessible by coupling plasma and surface chemistry, and to exploit these metastable species for novel surface reactions. Casey O’Brien and William Schneider will collaboratively explore these concepts in the context of nitrogen activation. Recent unpublished work in the O’Brien lab suggests that metastable azides, or N3, are stabilized by metal surfaces during exposure to N2 plasmas. While preliminary experiments indicate that LTP(low temperature plasma)-exposed metal surfaces can accommodate metastable N3 species, there are many fundamental science questions that remain unanswered: (i) What is the identity (N2, N3, or other) and nature of this species? (ii) Is this species formed in the plasma first and subsequently trapped by the metal surface, or does the surface facilitate its formation? (iii) How reactive are these surface-adsorbed species towards other reactants? This project will address these fundamental science questions to develop strategies to exploit metastable species generally, and azides specifically, to drive chemical transformations that cannot be achieved by conventional thermal catalysis or plasma alone. To this end, this project integrates experimental and computational approaches to clarify the mechanisms by which atmospheric pressure plasmas couple with solid surfaces to access and stabilize metastable N3 species and explore the potential to exploit these metastable states to drive novel reactions. The work leverages state-of-the-art in-situ spectroscopy techniques developed in the O’Brien, and density functional theory calculations that predict the relationship between surface composition, structure, products, and reactivity, providing a theoretical framework for understanding and guiding experiments.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.

在化学系化学催化项目的支持下，圣母大学的凯西奥布莱恩和威廉施耐德正在合作（1）澄清大气压等离子体与固体表面耦合以获得和稳定亚稳态氮物种的机制，以及（2）探索利用这些亚稳态驱动新反应的潜力。大气压等离子体与非均相催化剂（等离子体催化）的集成最近获得了相当大的关注，因为其有可能进行使用常规热催化难以或不可能的转化，并且在由可再生电力供电的模块化单元中。实现这一潜力将导致更节能和环境可持续的化学工艺。尤其是氮活化在等离子体催化界引起了极大的兴趣，因为等离子体能够活化强的二氮三键。奥布莱恩实验室的初步工作表明，与等离子体催化相关的吸附氮物种的类型可能比以前认为的更丰富。该项目的重点是澄清等离子体产生的氮物种的性质和反应性，使用光谱技术开发的奥布莱恩实验室和计算方法在施耐德实验室。基于理论的光谱方法和概念验证催化实例将广泛影响催化科学和技术。这项研究还将通过培养研究生在实验和计算研究、交流、科学严谨性和研究道德行为方面的能力来加强高等科学教育。这项提议探索了一种策略，可以通过耦合等离子体和表面化学来获得、稳定和浓缩热不可及的亚稳态中间体，并利用这些亚稳态物种进行新的表面反应。凯西奥布莱恩和威廉施耐德将合作探索这些概念的背景下，氮活化。奥布莱恩实验室最近未发表的工作表明，亚稳态叠氮化物或N3在暴露于N2等离子体期间被金属表面稳定。虽然初步实验表明，LTP（低温等离子体）暴露的金属表面可以容纳亚稳态N3物种，但仍有许多基本的科学问题没有得到解答：（i）这种物种的身份（N2，N3或其他）和性质是什么？(ii)这种物质是先在等离子体中形成，然后被金属表面捕获，还是表面促进了它的形成？(iii)这些表面吸附的物质对其他反应物的反应性如何？该项目将解决这些基本的科学问题，以开发利用亚稳态物质的策略，特别是叠氮化物，以驱动传统热催化或等离子体无法实现的化学转化。为此，该项目整合了实验和计算方法，以澄清大气压等离子体与固体表面耦合以访问和稳定亚稳态N3物种的机制，并探索利用这些亚稳态来驱动新反应的潜力。这项工作利用了奥布莱恩开发的最先进的原位光谱技术，以及预测表面组成、结构、产物和反应性之间关系的密度泛函理论计算，为理解和指导实验提供理论框架。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响进行评估来支持审查标准。