Collaborative Research: Understanding the Correlation between Water Electrolysis and Chemical Environment in Aqueous Electrolytes

With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professors Ji and Fang of Oregon State University in collaboration with Professor Greaney of the University of California, Riverside will explore the roles of local solvation structures in expanding the stability of water-based electrolytes for energy storage technologies. While previous efforts to improve the water stability against electrolysis have focused on changes to the O–H bond strength, the team will pursue a new approach by considering the impact of changing the hydroxide and proton solvation energies. The team will use a combination of femtosecond stimulated Raman spectroscopy (FSRS) and ab initio molecular dynamics (AIMD) simulations to study electrolytes of varying salt concentrations, cations and anions, and pH values to support their hypothesis that the electrochemical window of aqueous solutions can be expanded by discouraging their solvation of hydroxides and protons, the byproducts of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Their studies will elucidate key factors in chemical environment that dictate HER and OER onset potentials in aqueous electrolytes. Besides three graduate students who will directly perform the project tasks, the three PI’s labs will engage in outreach activities via online videos and in-person chemistry summer camps. This collaborative research project by Ji and Fang Labs at Oregon State University and Greaney Lab at UC Riverside will systematically investigate how solvation environments in aqueous electrolytes affect water’s HER and OER as well as the electrolytes’ resulting electrochemical stability window (ESW). The team will reveal how the local chemical environment with various cations and anions at low temperatures affects the electrolytic properties of aqueous solutions, and identify a richer set of Raman spectrum descriptors and predictors for chemical environments in concentrated aqueous electrolytes via PIs’ complementary expertise in electrochemistry, FSRS, and atomistic modeling. The direct observation of water’s H–O–H bending mode and use of a photoacid will provide deep insights into water’s local environment, bridging kinetics on ultrafast timescales to thermodynamics at equilibrium. The broader impacts of this work involve the development of a powerful experimental and theoretical platform to rationally design aqueous electrolytes with a significantly expanded or suppressed ESW for safe grid-scale storage batteries and green hydrogen production. The project, with cross-disciplinary knowledge and in the context of battery technology, will effectively engage STEM learners with combined science and engineering mindsets and natural curiosity about water in a myriad of applications. 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.