Excellence in Research: Transition metal carbides and nitrides supported single-atom catalysts for aqueous-phase methanol reforming

氢是一种清洁燃料，主要通过高温下碳氢化合物的催化重整从化石资源中生产出来。或者，通过甲醇等简单醇的水相重整，可以在低温下更高效地生产它。该项目探索了利用新型催化剂从甲醇(一种可再生原料)中生产氢气的可行性，该催化剂旨在液体环境中的低温下高效工作。与此同时，该项目为一个多学科研究计划奠定了基础，该计划在计算科学领域为代表不足的非裔美国学生提供研究和教育机会，同时更广泛地加强佛罗里达农业和机械大学(FAMU)的研究能力，这是一所历史上的黑人学院和大学(HBCU)。该研究涉及在低成本过渡金属碳化物(TMC)和氮化物(TMN)支撑的单原子催化剂上进行甲醇水相重整(APRM)的计算和实验相结合的研究。SACS是一类新兴的材料，具有近100%的金属利用率，具有均相和多相催化剂的综合优势。理论计算将通过实验测量来验证，以揭示过渡金属碳化物和氮化物(TMCs和TMN)上负载的铂、钯、Rh和镍囊的稳定性和构效关系。该项目包括三个目标：1)通过密度泛函理论(DFT)计算、机器学习(ML)方法和超高真空下的扫描隧道显微镜/光谱(STM/STS)测量，研究沉积在不同TMCs和TMN上的SARC的稳定性和电子结构；2)通过与原位和非原位STM确定的催化剂结构相关联的DFT模拟，确定APRM在稳定SAC上的活性中心和反应机理；以及3)应用动力学蒙特卡罗(KMC)模拟和气液间歇反应器实验结果，确定APRM的潜在候选SAC。本项目对SAC结构组成和稳定性的原子学理解，以及APRM的机理洞察，有望推广到其他SAC构型和其他醇类重整反应中。除了技术方面，该项目还包括教育和外联活动，重点关注少数群体和代表不足的群体，从K-12到研究生，并涉及学生与当地高中、塔拉哈西社区学院和FAMU附属发展研究学校的互动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Hydrogen, a clean fuel, is primarily produced from fossil resources via the catalytic reforming of hydrocarbons at high temperatures. Alternatively, it can be produced more efficiently at low temperature through the aqueous-phase reforming of simple alcohols such as methanol. The project explores the feasibility of hydrogen generation from methanol (a renewable feedstock) as facilitated by novel catalysts designed to work efficiently at low temperatures in liquid environments. Concomitantly, the project lays the groundwork for a multidisciplinary research program providing research and education opportunities for underrepresented African American students in the area of computational sciences, while more broadly strengthening the research capability of Florida Agricultural and Mechanical University (FAMU), a historically black college and university (HBCU).The study involves a combined computational and experimental study of aqueous-phase reforming of methanol (APRM) on single-atom catalysts (SACs) supported on low-cost transition metal carbides (TMCs) and nitrides (TMNs). SACs are an emerging class of materials that offer near 100% metal utilization and possess the combined advantages of homogeneous and heterogeneous catalysts. Theoretical calculations will be validated with experimental measurements to unravel the stability and structure-activity relationships of Pt, Pd, Rh, and Ni SACs supported on transition metal carbides and nitrides (TMCs and TMNs). The project embraces three objectives: 1) investigation of stability and electronic structure of SACs deposited on various TMCs and TMNs via density functional theory (DFT) calculations, machine learning (ML) methods, and scanning tunneling microscopy/spectroscopy (STM/STS) measurements in ultrahigh vacuum; 2) identification of active sites and reaction mechanisms of APRM on stable SACs through DFT simulations of reaction energetics associated with catalyst structures identified by in-situ and ex-situ STM; and 3) application of Kinetic Monte Carlo (KMC) simulations and results of gas-liquid batch reactor experiments to identify promising SAC candidates for APRM. The atomistic understanding of structure compositions and stability of SACs, as well as the mechanistic insight of APRM obtained from this project, is expected to be transferable to other SAC configurations and other alcohol reforming reactions. Beyond the technical aspects, the project involves educational and outreach activities focused on minorities and underrepresented groups ranging from K-12 through graduate students, and involving student interactions with local high-schools, Tallahassee Community College, and the FAMU affiliated Developmental Research School.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.