Enhanced Water Oxidation Activity of the Cobalt(II, III) Oxide Electrocatalyst on an Earth-Abundant-Metal-Interlayered Hybrid Porous Carbon Support

Supports over which electrocatalysts are deposited play a crucial role in the oxygen evolution reaction (OER), because they influence the surface roughness, morphology, electronic structure, and conductivity of electrocatalysts. In this context, we designed a hybrid carbon support having an earth-abundant metal as an interlayer between a Co3O4 electrocatalyst and a carbon support. The present approach resulted in an electrode that was three dimensional with high porosity, provided low resistance to parallel electron conduction pathways through the metallic interlayer, and modulated the electrocatalytic activity of Co3O4 by affecting its electronic structure. To rationalize the effect of the metal interlayer, a range of nonnoble earth-abundant metals (e.g. Cu, Mo, Ti, Al) were ex-plored, of which the Cu-modified carbon support resulted in maximum specific activity (i.e. activity per electrochemical surface area) for the OER. Whereas both the electronegativity and conductivity of the metal interlayer were found to influence the OER activity, the dominant controlling factor in the explored systems was conductivity. The specific activity of the OER of electrodeposited Co3O4 was found to have a near-linear relationship between the electrical conductivity and the electron-donor metals (e.g. Ti, Al) and another near-linear relationship having different intercepts with electron-acceptor metals (e.g. Cu, Mo, W). The above understanding can be useful in increasing the OER activity of electrocatalysts through support-electrocatalyst interactions.