Quantifying Surface Chemical Intermediates and Interfacial Redox Processes via Combined Raman Spectroscopy and Scanning Electrochemical Microscopy

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Chemical reactions at electrode surfaces are essential for a large number of applications, which range from powering fuel cells to cleaning water. In addition, understanding the intimate details of those reactions is crucial to bolster renewable energy technologies. Unfortunately, all these important reactions at electrodes also display a broad range of complicated chemical reaction pathways that happen at a very small region close to the surface of the electrodes. This makes it very difficult to observe and understand how these reactions happen at the atomic level, which is key to improving them. Professor Rodriguez-Lopez addresses this pressing challenge by introducing a measurement technique where laser light, in combination with very small probes in a particular arrangement, are used to identify the chemicals formed at the surface of electrodes, while also identifying the reactions in which they participate. By carefully choosing some key electrode materials, Rodriguez-Lopez improves the ability to measure very small amounts of chemicals that speed up the product formation. The methods help understand how a promising catalyst for a fuel cell can lose activity, and how oxygen atoms at metals participate in key processes for energy technologies. The research plan benefits society by including hands-on activities for Hispanic children in the community. Advances electrochemical science is also taught to a diverse group of students to ensure a workforce with training at the forefront of science. With this award, the Division of Chemistry is funding Dr. Joaquin Rodriguez-Lopez at the University of Illinois to study development of a hybrid microscopy system for examination of chemical reactions at electrode surfaces. Exploring the mechanisms of interfacial electrocatalytic processes is challenging, however knowledge about reactive intermediate identity, surface coverage, and reactivity, is critical in understanding in situ approaches. Dr. Rodriguez-Lopez investigates a simultaneous, spatiotemporally matched approach for the in situ quantification of reactive intermediates at electrochemical interfaces through integration of scanning electrochemical microscopy with Raman spectroscopy. The research may improve the spatial resolution of the technique by using micro and nanoelectrodes of different sizes. Rodriguez-Lopez aims to help solve long-standing challenges in electrocatalysis by correlating electrode reactivity to surface properties of materials in fuel cells, electrolyzers, and batteries, as well as in systems for water remediation, electrosynthesis, and corrosion prevention. The project integrates educational and outreach plans that engage students of Hispanic origin in scientific activities, as well as the organization of an electrochemical bootcamp that helps ensure the presence of a diverse workforce at the forefront of electrochemical and measurement science.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.