Modeling electrocatalysts in operating conditions: Surface restructuring and catalytic activity

随着可再生电力越来越多地来自风能和太阳能等来源，电化学在未来几年将在清洁能源、化学制造和环境过程中发挥重要作用。该项目专注于两个电化学反应，即从水中生产氢气的析氢反应(HER)和将二氧化碳转化为更高价值产品的二氧化碳还原反应(CO2RR)。这两个反应都是在催化剂的推动下进行的。铜基催化剂是迄今发现的活性最高的催化剂之一，但与许多电催化剂一样，它们的化学结构在反应条件下会发生变化。该项目的重点是了解重建过程，目标是设计更活跃、更有选择性和更稳定的催化剂。具体地说，该项目开发并使用计算技术来预测结构变化，以响应关键的电化学过程变量。除了技术方面，该项目还包括一个针对高中教师的培训计划，将可持续发展和能源的主题带到他们的课堂上，同时向学生介绍迅速崛起的分子建模领域。该项目将通过独特的第一原理、多尺度随机理论模拟，确定用于析氢和CO2电还原反应的铜基电催化剂在真实的电位、溶剂和电解液条件下的表面重构。我们将结合实验研究电势诱导重构对这些反应的电催化机理、活性和选择性的影响。现场表征表明，在操作条件下，电催化剂的表面结构发生了强烈的修饰。然而，目前还不可能确定活性表面的原子结构，因此，这些重建对机制的影响尚不清楚。所提出的多尺度第一原理模拟似乎是解释界面结构的最合适的方法。大体上，可能会出现新的反应机制。将研究二氧化碳电还原与析氢的选择性(后者是应用中的主要障碍)。PI实验室独有的几种理论方法，包括电化学势、溶剂效应、全局优化算法和STM图像模拟，将被改进、调整和合并，以使这项研究成为可能。提出了与实验密切相关的建议，无论是在结构方面，还是为了验证预测的动力学和选择性，都使用了操作手扫描隧道显微镜(STM)。这个项目将教育年轻的研究人员现代表面化学和催化技术，包括逼真的建模、方法开发、量子力学和统计力学。此外，学生还将学习如何将建模工作与实验数据和能力联系起来。该培训将促进一支高技能的劳动力队伍，以应对可持续燃料和化学品制造方面的全球挑战。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。

Electrochemistry is slated to play a large role in clean energy, chemical manufacturing, and environmental processes in coming years, as renewable electricity becomes increasingly available from sources such as wind and solar energy. The project focuses on two electrochemical reactions, the hydrogen evolution reaction (HER) to produce hydrogen from water, and the carbon dioxide reduction reaction (CO2RR) to convert CO2 to higher-value products. Both reactions are facilitated by catalysts. Copper-based catalysts are amongst the most active identified to date, but as with many electrocatalysts, their chemical structure changes under reaction conditions. The project focuses on understanding the reconstruction process with the goal of designing more active, selective, and stable catalysts. Specifically, the project develops and employs computational techniques to predict structural changes in response to key electrochemical process variables. Beyond the technical aspects, the project incorporates a training program for high-school teachers that brings the topics of sustainability and energy to their classrooms, while introducing students to the rapidly emerging area of molecular modeling. The project will determine, by unique first-principles, multi-scale stochastic theoretical simulations, how the surface of copper-based electrocatalysts used for the hydrogen evolution and CO2 electroreduction reactions restructures in realistic conditions of potential, solvent, and electrolyte. The influence of the potential-induced reconstruction on the electrocatalytic mechanism, activity, and selectivity of these reactions will be studied, in link with experiments. There is evidence from in-situ characterization that the surface structure of electrocatalysts is strongly modified in operational conditions. However, it is not yet possible to determine the atomic structure of the active surface, and thus, the implications of these reconstructions on the mechanisms are unknown. The proposed multiscale first-principle simulations appear to be the most adequate approach to elucidate the interface structure. Principally, new reaction mechanisms may emerge. The selectivity of CO2 electroreduction versus hydrogen evolution (the latter being a major hurdle in applications) will be studied. Several theoretical methods unique to the laboratories of the PIs, including the incorporation of electrochemical potential, solvent effects, global optimization algorithms, and STM image simulations, will be advanced, adapted, and merged to make this research possible. Close connection to the experiment is proposed, both for structural aspects, with operando scanning tunneling microscopy (STM), and to validate the predicted kinetics and selectivity. This project will educate young researchers in techniques of modern surface chemistry and catalysis, including realistic modeling, method development, quantum mechanics, and statistical mechanics. In addition, students will learn how to connect modeling efforts to experimental data and capabilities. The training will promote a highly-skilled workforce to address global challenges in the manufacture of sustainable fuels and chemicals.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.