Enhancing Water Oxidation Performance of Transition Metal Oxides by Atomically Precise Heteroatom Doping

Heteroatom doping is an effective strategy for tuning the electronic structure and stability of non-noble transition metal (e.g., Fe, Co, and Ni) oxides for cost-efficient oxygen evolution reactions (OERs), but conventional doping methods usually give rise to unpredictable and uneven doping sites or even phase separation. Here, we develop an interfacial diffusion strategy for atomically precise doping of less electronegative heteroatoms to the lattices of 3d transition metal (Fe, Co, Ni) oxides, leveraging on the simple yet effective lattice-match principle. Taking Fe2O3 as a model, Cr can be uniformly doped and arranged in the alternating cation layers against Fe. As-prepared FeCrO3 lowers the overpotential from 438 mV of Fe2O3 to 258 mV at 10 mA cm-2 in 1.0 M KOH and can operate for at least 1100 h with almost no performance attenuation at 250 mA cm-2. Multiple characterizations reveal that the ordered arrangement of Cr around Fe sites induces an electron flux from Cr to Fe, stabilizing active Fe2+ species and accelerating the Fe2+/Fe3+/Fe4+ redox cycle, thereby promoting water activation and *OH dehydrogenation. Besides, ordered Cr doping improves the OER stability of FeCrO3 by preserving surface basicity through Lewis acidic Cr3+ and stabilizing the Fe-O bond to shift the reaction mechanism from lattice oxygen oxidation (LOM) to adsorbate evolution (AEM). This atomically precise doping strategy is easily scaled-up for kilogram production of FeCrO3, and it is readily extendable to other transition metal oxides (e.g., NiO and Co3O4). Our work underscores the importance of atomically precise surface engineering in the manufacture of catalysts.