Cation-Dependent Multielectron Kinetics of Metal Oxide Splitting

Direct electrolytic extraction of metals from metaloxides is a promising process for the sustainable production ofmetals. In this work, we elucidate the inherent thermodynamicdriving forces behind the reduction of metal oxides to metals (M-OER). It is shown that the thermodynamics of M-OER can besystematically tuned via the interactions of oxygen with theparticipating metal cations as a function of metal-oxygen covalency,oxygen-oxygen covalency, and metal-oxygen ionicity. We screenboth group 1 elements and metals that are able to exist in the +2oxidation state for M-OER thermodynamics. Li, Fe, and Co areidentified as having low thermodynamic overpotentials for electro-lytic extraction from their metal oxides due to interactions between oxygen and these metals being neither too strong (covalent) nortoo weak (ionic). We further show that the bulk formation energies are predictive of M-OER reaction energetics on surfaces bydeveloping unified design principles for tuning the thermodynamics of these reduction reactions both in bulk oxides and on surfaces.

Automated summary

This work elucidates the thermodynamic driving forces behind the reduction of metal oxides to metals and provides a promising process for the sustainable production of metals through the tuning of oxygen-metal interactions.