Cobalt-/Copper-Containing Perovskites in Oxygen Evolution and Reduction Reactions

The design and engineering of electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key to sustainable development. The structure of ABO(3) perovskites allows engineering of their electronic properties such as the energy of the Fermi level and the valence band maximum, which directly impact their electrocatalytic activity. Moreover, the covalency of the B-O bond and its electron affinity increase the polarization of -OH adsorbed at B-sites, leading to enhanced kinetics of OER. Here, a series of cobalt/copper perovskites (Ca0.8Sr0.2Co1-xCuxO3-delta (x = 0, 0.5, and 1)) were prepared. In our finding, copper with a larger electron affinity compared to cobalt accelerates OER, while the coexistence of Co/Cu at the B-sites increases the activity of the system in ORR. The mechanism of OER is discussed based on the pH dependency on the reversible hydrogen electrode (RHE) scale and galvanostatic oxidation measurements. The results point to the lattice oxygen mechanism as the prevailing one.