CeO 2 Functionalized Cobalt Layered Double Hydroxide for Efficient Catalytic Oxygen-Evolving Reaction.

Water splitting to produce hydrogen is an effective means to alleviate the energy crisis. The anodic oxygen-evolving reaction (OER) limits the overall efficiency due to its high energy barrier. To address this, layered double hydroxides (LDHs) with high catalytic activities have been widely studied, especially those modified with CeO 2 , either bound to the surface or doped into interior. However, experimental evidence for the atomic-level understanding of the mechanism for the enhanced catalytic performance is conspicuously missing. Herein, anchoring CeO 2 nanoparticles onto Co LDH, based on the thoughts of loading capacity and size effect to regulate the properties of the interface and to optimize the performance, is attempted. The electronic interactions are studied by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS), revealing electron transfer from Co 2+ to Ce 4+ that leads to an increase in Co 3+ . The strong Lewis acidity of Co 3+ helps the binding of OH - , which is conducive to the formation and transformation of oxygen-containing intermediates. Providing evidence is the formation of one of the key intermediates Co-OOH at a sizably reduced potential as monitored by in situ Raman spectroscopy. With this work, the atomic level correlation of site-specific electronic interactions with the enhanced catalytic performance is clearly established.