【摘要】 以Co₃O₄为代表的Co基尖晶石氧化物因其在析氧反应（Oxygen Evolution Reaction,OER）中表现出优异的催化性能而备受关注，但其主要活性位点是四面体Co²⁺（T_d）还是八面体Co³⁺（O_h）仍存在争议。本研究通过无OER活性的Al元素替代进行配位调控，合成了只有四面体Co²⁺（T_d）位点的CoAl₂O₄尖晶石氧化物和Co₃O₄进行对比，以明确真正的OER活性位点。采用X射线衍射（X-ray Diffraction,XRD）、透射电子显微镜（Transmission Electron Microscope,TEM）和X射线吸收精细结构（X-ray Absorption Fine Structure,XAFS）表征Co₃O₄和CoAl₂O₄的形貌与原子结构，并利用高能量分辨荧光探测X射线吸收谱（High Energy Resolution FluorescenceDetected X-ray Absorption Spectroscopy,HERFD-XAS）和电化学表征获取Co₃O₄和CoAl₂O₄的精细电子结构和碱性OER性能。在10 mA·cm^-2电流密度下，Co₃O₄的过电位为375 mV，优于CoAl₂O₄的404 mV。HERFD-XAS结果表明，相较于CoAl₂O₄,Co₃O₄在边前约7 712 eV处探测到非局域电子激发峰，这表明具有八面体配位钴的Co₃O₄存在更强的金属-金属相互作用，因而表现出更优异的碱性OER性能。本研究从电子结构分析和活性位点识别的角度，为设计高性能OER催化剂提供了新见解。更多还原

【Abstract】 [Background] Cobalt-based spinel oxides, exemplified by Co₃O₄, have attracted significant attention for their exceptional catalytic performance in the oxygen evolution reaction（OER）, yet controversy persists regarding whether tetrahedral Co²⁺（Td） or octahedral Co³⁺（Oh） sites serve as the primary active centers. [Purpose] This study aims to identify the true OER active sites in Co₃O₄ through coordination engineering using OER-inactive Al substitution. [Methods] Firstly, Co₃O₄ and CoAl₂O₄ spinel oxides were synthesized via coprecipitation method, where Al occupies only octahedral sites occupied only by Al, leaving Co²⁺ exclusively in tetrahedral positions in CoAl₂O₄. Then, the morphological and atomic structures of both catalysts were characterized using X-ray diffraction（XRD）, transmission electron microscopy（TEM）, and X-ray absorption fine structure（XAFS） spectroscopy. Finally, highenergy-resolution fluorescence-detected X-ray absorption spectroscopy（HERFD-XAS） and electrochemical measurements were performed to probe the refined electronic structures and evaluate the alkaline OER performance. [Result] Observation results indicate that Co₃O₄ exhibits superior catalytic activity with an overpotential of 375 mV at 10 mA·cm^-2, which is 29 mV lower than that of CoAl₂O₄（404 mV）. The Tafel slope of Co₃O₄（66.40 mV/dec） is significantly smaller than that of CoAl₂O₄（107.80 mV/dec）, indicating faster OER kinetics. HERFD-XAS reveals a distinct pre-edge feature at approximately 7 712 eV in Co₃O₄, attributed to non-local electronic excitation via the Co1s→Co4p→O2p→Co3d pathway, which is absent in CoAl₂O₄. Octahedral Co³⁺（Oh） sites in Co₃O₄ serve as the primary OER active centers, exhibiting 7.2% lower overpotential and 38.5% reduction in Tafel slope compared to tetrahedral Co²⁺（Td）-only CoAl₂O₄. [Conclusions] Results of this study show that the enhanced performance originates from stronger metal-metal interactions in octahedral sites, which optimizes d-orbital electronic structure and accelerates OER kinetics, providing atomic-level insights for designing high-performance transition metal oxide catalysts.更多还原