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초록

In transition metal oxide (TMO) based oxygen evolution reactions (OER) electrocatalysts, the lattice oxygen-mediated mechanism (LOM) has emerged as a more efficient pathway for OER compared to the traditional adsorbate evolution mechanism (AEM). LOM activation critically depends on covalency of transition metals (TMs) with high-valence states. In this study, we leverage the high electron affinity and strong oxophilicity of cerium (Ce) to fine-tune the TM-O bonding state of NiO through a one-step electrodeposition method. Ce and Ni co-electrodeposition forms a CeO2/NiO heterostructure that shifts from AEM to LOM via enhanced covalency between high- valence Ni and lattice oxygen and promotes electron transfer from NiO to CeO2. This CeO2/NiO heterostructure achieves a low overpotential of 160 mV and a Tafel slope of 32.68 mV dec(-)1 at 10 mA cm(-)2. Additionally, it exhibits a low cell voltage of 1.84 V and only a 1.19% voltage increase over 100 h at a high current density of 1 A cm(-)2 in an anion exchange membrane water electrolyzer. These results represent the role of oxophilic Ce and CeO2 in stabilizing the Ni oxidation states, thereby ensuring superior LOM-driven OER performance.

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