Uncovering the Geometry Activity of Spinel Oxides in Li-CO2 Battery Reactions

Oxide catalysts are attractive in Li-CO2 batteries for their activity and stability. However, discerning the active sites and contributing factors for battery reactions is still challenging due to the presence of passive spectator species. Herein, we use Co3O4 to uncover the geometry-dependent activity and propose the key parameters that govern reactions in the Li-CO2 batteries. We find that octahedral Co plays a dominant role in promoting battery reaction kinetics due to its strong interaction with reactants. In particular, we investigate the correlations between the d-orbital configurations in octahedral sites and CO2 activity, where low eg filling facilitates CO2–catalyst bonding. Therefore, catalysts containing octahedral Co, especially Co3O4, show high activity and durability with a low overpotential of 1.0 V and a cycling life of 600 h. Our study exemplifies the role of local electronic and geometry structures in catalysis, which provides insight into catalyst design in Li-CO2 batteries.