Catalyst-ionomer interactions in electrochemical systems

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Electrochemical energy conversion systems including polymer electrolyte membrane (PEM) fuel cells and water electrolyzers are central to reducing global fossil fuel dependence through widespread implementation of renewable hydrogen. Great improvements have been made in reducing the amount of expensive noble metals needed for high-performance. Nevertheless, significant opportunity exists for further improving fuel cell/electrolyzer performance through optimization of the interface between the catalyst and the ion-conducting medium known as the ionomer. The study utilizes state-of-the-art instrumentation, combined with a suite of electrochemical characterization methods, to gain unprecedented insight regarding the interfacial interactions between the catalyst layers and the ionomer. The resulting fundamental insights regarding catalyst-ionomer interactions across a range of catalytic systems – under conditions emulating device operation – will translate directly to improved designs of durable, low-cost PEM fuel cells and other water electrolyzer systems. The study involves a set of interconnected research and educational goals, both aimed at expanding knowledge of electrochemical devices, ensuring a highly trained future workforce, and highlighting the importance of renewable energy to the broader public.The project will develop fundamental understanding of catalyst-ionomer interfaces and interactions, determine the effects of catalyst and support chemistry and morphology on these interfaces and interactions, and track evolution of interfacial structure and composition under sustained electrochemical reaction. The project will also establish best practices and protocols for PEM catalyst layer surface studies that can be applied to other systems. A variety of X-ray photoelectron spectroscopy experiments under in situ conditions, in conjunction with complementary characterization, will investigate the evolution of both catalyst-ionomer interactions and interfaces during exposure to relevant conditions for three material sets of increasing complexity: 1) ionomer thin films, 2) catalyst-ionomer composites, and 3) integrated electrodes. The resulting insights will guide future work in designing novel catalyst systems and electrodes with optimized surfaces and interfaces as well as improved performance and durability. Knowledge obtained from this project will be disseminated to a wide audience through publications, participation in workshops and conferences, and close interactions with scientists from academia, national labs, and industry. The investigator will contribute to the education of STEM teachers through the AVS Science Educators workshop (SEW) and through the Summer Workshop on Energy Education for Teachers (SWEET) program at the investigator’s institution. The project also focuses on increasing participation from underrepresented minority groups and training future leaders capable of transforming scientific understanding related to clean-energy and climate impact via renewable resources.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.