NSF-DFG Echem: Elucidating Surface Structure Contribution of Facets, Steps and Kinks in Electrocatalysis of the Oxygen Evolution and Reduction Reactions

This project is an international collaboration between the Colorado School of Mines (USA), the National Renewable Energy Laboratory (USA), Carl von Ossietzky University Oldenburg (Germany) and the German Aerospace Center-Deutsches Zentrum für Luft- und Raumfahrt (DLR) in Germany. Electrolysis is a key technology to generate green hydrogen using renewable energies while fuel cells are crucial for converting stored energy into electrical energy.

Both technologies require catalysts which currently struggle with sluggish kinetics limiting their efficiencies and thus requiring the development of improved electrocatalysts. Currently, water electrolyzers and fuel cells use metals that are scarce and expensive thereby limiting large-scale commercialization. In this research program we target the use of earth abundant materials such as first row transition metals (Ni, Fe, Co, Mn or Cu) in the form of metal oxides as electrocatalysts through fundamental study and manipulation of the surfaces.

This project brings together American and German scientists and engineers to work on this challenging project thus providing a unique educational experience for the students involved.

The overarching goal of this project is to create higher performing, more durable non-precious metal catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Alkaline conditions established by the chemical nature of an anion exchange membrane (AEM) enable the usage of alternative catalytic materials for the OER in AEM water electrolysis (AEMWE) and ORR in AEM fuel cells (AEMFC).

The rock salt structure enables synthesis of shape-controlled metal oxide particles with (111) or (100) surfaces, which are not (easily) achievable for other crystal structures like spinels or pervoskites, allowing elucidation of their role in oxygen electrocatalysis. Further, these materials offer ideal platforms to systematically study the effects of tailoring the surfaces with steps and kinks and making multi-metal oxides with elements of similar ionic radii (e.g.

Co, Mn, Fe). Our central hypothesis is that controlling the surface termination and facet exposure of a catalyst can alter the coordination and bonding environments at the surface thus changing the reactant-catalyst interaction and the electrocatalytic OER/ORR activity. Therefore, the connection between synthesis, surface morphology and electrochemical performance will provide the underlying fundamental knowledge crucial for the design of catalysts.

This research was funded under the NSF-DFG Lead Agency Activity in Electrosynthesis and Electrocatalysis (NSF-DFG EChem) opportunity NSF 20-578.

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.