Sustainability in energy conversion processes requires materials that are designed to be high-performance and durable, yet cost-effective. Alkaline electrochemical systems provide an opportunity to explore non-precious metal alternatives to precious metal-based electrocatalysts, where the use of non-precious metals would allow a significant reduction in cost. Recently, iron-incorporated nickel oxide/hydroxide catalysts have been a focus for alkaline electrooxidation reactions, and in particular, for the oxygen evolution reaction. This focus results from the newly identified role of iron in controlling catalyst activity. While fundamental research largely focuses on the study of bulk films, there is a need for catalysts that have high mass normalized activities, or, high surface area-to-volume ratio. Our research interests in this area focus on the development of FeNi bimetallic nanoparticles. We develop nanoparticle materials for specific electrochemical or chemical reactions, such as the oxygen evolution reaction, through variation of bimetallic composition, morphological structure, extent of oxide/oxyhydroxide phases, and ligand concentration and molecular structure. Much of our work focuses on the use of complementary high resolution characterization tools to understand how synthesis directs nanoparticle structure and how structure impacts electrocatalytic activity. In this talk, I will discuss some of our on-going work on iron-nickel oxide/hydroxide nanoparticle materials suite that demonstrates promising performance for the oxygen evolution reaction. I will discuss how we synthesize our nanoparticles, how we control nanoparticle properties such as morphology and composition, and our understanding of how nanoparticle properties influence catalyst performance. In particular, I will focus on our recent results with synchrotron-based x-ray absorption spectroscopy on both dry, ex situ samples and with an operando electrochemical setup. These results illustrate the dynamic behavior of iron-nickel hydroxide electrocatalysts in the alkaline environment and suggest that during the oxygen evolution reaction, both the iron and the nickel undergo changes to oxidation state and coordination environment.

FexNi1-xO(H)y nanoparticles for alkaline electrocatalysis: Understanding the chemical structure of complex nanocatalysts

2019 Fall National Meeting

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