Atomic-level correlation between the electrochemical performance of an oxygen-evolving catalyst and the effects of CeO₂ functionalization

Herein, we prepared a bimetallic layered double hydroxide (FeCo LDH) featuring a dandelion-like structure. Anchoring of CeO₂ onto FeCo LDH produced interfaces between the functionalizing CeO₂ and the parent LDH. Comparative electrochemical studies were carried out. Onset potential, overpotential, and Tafel slope point to the superior oxygen-evolving performance of CeO₂-FeCo LDH with respect to FeCo LDH, therefore, demonstrating the merits of CeO₂ functionalization. The electronic structures of Fe, Co, and Ce were analyzed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) from which the increase of Co³⁺ and the concurrent lowering of Ce⁴⁺ were established. With the use of CeO₂-FeCo LDH, accelerated formation at a sizably reduced potential of Co-OOH, one of the key intermediates preceding the release of O₂ was observed by in situ Raman spectroscopy. We now have the atomic-level and location-specific evidence, the increase of the active Co³⁺ across the interface to correlate the enhanced catalytic performance with CeO₂ functionalization. [Figure not available: see fulltext.]