Co/Fe Oxyhydroxides Supported on Perovskite Oxides as Oxygen Evolution Reaction Catalyst Systems.

Co/Fe oxyhydroxide catalysts have been deposited onto the surface of amorphous carbons or different perovskite oxides. By performing electrochemical characterizations and operando X-ray absorption spectroscopy measurements, novel insights into Co/Fe oxyhydroxide catalysts and their interactions with perovskite oxides have been revealed. The addition of Fe into Co oxyhydroxide catalysts greatly enhances the oxygen evolution reaction (OER) activity by stabilizing the Co cations into a lower oxidation state under operative conditions compared to the case of undoped Co oxyhydroxide. A beneficial Co/Fe electronic interaction for OER can also be achieved by depositing Co oxyhydroxide on Fe-containing oxide supports, such as the LaFeO3 perovskite. Finally, it was found that, despite the lower Fe content in the Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite structure, Co oxyhydroxides supported on this perovskite exhibit the highest OER activity. Therefore, our findings suggest that perovskite structures presenting a large content of oxygen vacancies and undergoing surface reconstruction, such as BSCF, offer the best interface for Co oxyhydroxides. Finally, profiting from the beneficial Co/Fe electronic interaction and perovskite interface interaction, the highest OER activity has been achieved by depositing Co/Fe oxyhydroxide on the surface of BSCF perovskite.