Understanding structure-activity relationships in disordered (oxy)hydroxide electrocatalysts

Hydrogen is a promising low- to zero-carbon resource and could pave the way to a clean energy economy across multiple sectors, including chemical manufacturing, agriculture, and transportation. Electrocatalysis is at the forefront of technologies that could help realize a hydrogen economy at scale. Earth-abundant, low-cost electrocatalysts that help chemically split water into hydrogen and oxygen are a promising platform for hydrogen generation. A major challenge is that electrocatalysts often undergo complex transformations during their operation, and these transformations are poorly understood. This project addresses this knowledge gap by combining experimental and computational techniques to probe these atomic level changes and understand how local structural changes impact electrocatalytic activity. The project will provide a rich ecosystem for training students in state-of-the-art computational and experimental techniques. The research results will be integrated into mentorship of undergraduate researchers and educational outreach programming incorporating computational and experimental aspects of research in electrochemistry. Disordered electrocatalysts have been shown to outperform crystalline ones. In many systems, electrochemical cycling leads to the formation of (oxy)hydroxide phases on the surface, which serve as the active electrocatalytic layer. While transition metal (oxy)hydroxides are among the most active and prominent alkaline oxygen evolution reaction (OER) electrocatalysts, the specific structural features responsible for their performance, particularly in their disordered forms, remain poorly defined. This project will establish structure-activity relationships for the (oxy)hydroxides as a model system, focusing on three sources of disorder for modulating the active site: iron incorporation, variation in proton decoration, and local structural distortions of the octahedra. The project will address several fundamental questions: What are the relevant types of disorder present in (oxy)hydroxides? How are these types of disorder related to the activity? Do these types of disorder lead to new active sites and/or more active sites? The project will employ a combined theoretical and experimental approach to achieve the research objectives. Electronic structure calculations based on density functional theory (DFT) will be used to evaluate OER free-energies. Measured vibrational, X-ray diffraction, and X-ray absorption spectra will be combined with simulated counterparts, alongside electrochemical characterization. These complementary tools will be used in a feedback loop to validate atomistic models against spectroscopic signatures and trends in electrocatalytic activity. The outcome, which will draw explicit connections between structural disorder and OER activity, will provide the necessary foundation for understanding how (oxy)hydroxide electrocatalysts evolve during electrochemical cycling. 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.