ABSTRACT

The project addresses catalytic electrochemical processes related to the production of ammonia (NH3) from water and nitrogen, and the oxygen evolution reaction (OER) needed to split water to produce hydrogen for energy storage and fuel and chemical production. Both processes offer alternatives to conventional processes that rely on hydrocarbon resources for the needed hydrogen. Thus the project will support NSF's initiatives in the areas of sustainable energy generation and Innovations at the Nexus of Food, Energy, and Water (INFEWS), the latter via the importance of NH3 as the world's primary raw material for nitrogen-based fertilizer production. In particular, the research is aimed at discovering efficient, nonprecious metal nanocatalysts for the targeted electrochemical processes that can operate at ambient temperature conditions rather than the high-temperature conditions required for hydrocarbon-based technologies. The electrocatalytic nitrogen reduction reaction (NRR) has the potential to generate NH3 at lower net energy consumption than the traditional Haber-Bosch thermal catalytic process which accounts for between 1 and 2% of world energy consumption.

Specifically, the project seeks advances in catalytic electrolyzers for both NRR and OER. The work will focus exclusively on nonprecious metal bimetallic catalysts operating in alkaline electrochemical environments, thus enabling low-cost, technology-enabling alternatives to the precious metals. The project is built on preliminary data suggesting that specific control of the spatial composition and morphology of heterostructured nanoparticles will enable enhanced catalytic activity and also establish fundamental understanding of composition-activity relationships for key bimetallic systems in nanoparticle form. The specific research objectives are: (1) to synthesize and characterize novel heteronanostructures of nonprecious Fe-Ni bimetals composed of a hetero-core with/without an alloyed shell, (2) to evaluate the reactivity and selectivity of the catalysts for electrochemical NRR and OER in alkaline systems, and (3) to develop in operando methods to correlate the structure and composition with electrocatalytic activity using x-ray absorption spectroscopy. Beyond the targeted reactions, introduction of low-cost, nonprecious nanoparticle catalysts are of increasing interest for a broad range of catalytic applications, including electrocatalysis. Validation of the proposed novel nonprecious nanostructures, where specific spatial composition is correlated with the performance metrics and in operando characterization, will enable an approach to catalyst design that could be widely applied to enable cost- and performance-competitive catalysts for commercialization. Furthermore, controlling catalyst selectivity through structural design would enable key advances for important reactions related to water treatment, energy conversion, and agriculture. To support this objective, an integrated approach of research and education will be established to increase student participation in STEM research, to pursue STEM majors, and to train next-generation leaders in the interdisciplinary field of nanocatalysts. The investigators will actively recruit students, especially unrepresented student groups, to their research programs. The research findings will be integrated into teaching for undergraduate and graduate curriculum development in both Chemistry and Chemical Engineering departments. In addition, the investigators will strengthen the current summer programs by involving K-12 teachers through American Chemical Society Science Coaches and the University of Arkansas Engineering Academy Programs, as well as organizing an annual workshop for students and K-12 teachers on Nanocatalyst Discovery.

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