Molecular Additives at the Catalyst Ionomer Interface

Abstract

The growth and viability of deep decarbonization through the hydrogen economy is dependent upon scientific advances that will address the existing political, regulatory, and technological barriers that currently hinder electrochemical energy technologies. The strong correlation between device-level performance and catalytic electrode activity/durability highlights the criticality of identifying the limiting processes and developing strategies to address these limitations. The goal of our group is to use fundamental insight derived from the study of well-defined systems to develop unique mitigation strategies, aimed at improving device-level performance, that go beyond simply varying electrocatalyst material properties. The interface between catalyst and ionomer in polymer electrolyte membrane fuel cells (PEMFC) greatly limits device performance through detrimental impacts to local reactant transport and reaction kinetics. Optimization of the catalyst/ionomer interface to not only mitigate these detrimental impacts, but to also beyond existing performance is a challenging task. In this presentation we will present our work in developing molecular interfacial modifying species to optimize the interaction between catalyst and ionomer. Integrating molecular components such as ionic liquids or caffeine both enhances the kinetics of the electrode reactions and limits the detrimental impacts of ionomer on the catalyst surface. We will present our fundamental understanding of why these molecular additives improve catalyst activity and limit the impacts of ionomer. We will also present our integration of these molecular moieties into next generation ionomers and their performance in PEMFC membrane electrode assemblies (MEA).