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.