Introduction of iron in various catalytic systems has served a crucial function to significantly enhance the catalytic activity toward oxygen evolution reaction (OER), but the relationship between material properties and catalysis is still elusive. In this study, by regulating the distinctive geometric sites in spinel, Fe occupies the octahedral sites (Fe³⁺_(Oh)) and confines Co to the tetrahedral site (Co²⁺_(Td)), resulting in a strikingly high activity (η_{j = 10 mA cm}⁻² = 229 mV and η_{j = 100 mA cm}⁻² = 281 mV). Further enrichment of Fe ions would occupy the tetrahedral sites to decline the amount of Co²⁺_(Td) and deteriorate the OER activity. It is also found that similar tafel slope and peak frequency in Bode plot of electrochemical impedance spectroscopy indicate that Co²⁺_(Td) ions are primarily in charge of water oxidation catalytic center. By means of electrochemical techniques and in situ X‐ray absorption spectroscopy, it is proposed that Fe³⁺_(Oh) ions mainly confine cobalt ions to the tetrahedral site to restrain the multipath transfer of cobalt ions during the dynamic structural transformation between spinel and oxyhydroxide, continuously activating the catalytic behavior of Co²⁺_(Td) ions. This material‐related insight provides an indication for the design of highly efficient OER electrocatalysts.

中文翻译：

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揭露高效掺铁电催化剂中发生氧气逸出反应的几何位点限制

在各种催化体系中引入铁已经起到了至关重要的作用，即显着增强了对氧释放反应（OER）的催化活性，但是材料性能与催化之间的关系仍然难以捉摸。在这项研究中，通过调节尖晶石中独特的几何位点，Fe占据了八面体位点（Fe ³⁺ _（Oh）），并将Co限制在四面体位点（Co ²⁺ _（Td））中，从而产生了惊人的高活性（η _{j = 10 mA cm} ^-2 = 229 mV，ηj _{= 100 mA cm} ^-2 = 281 mV）。Fe离子的进一步富集将占据四面体位点，从而降低Co ²⁺ _{（Td）的量}并降低OER活性。还发现，在电化学阻抗谱的波德图中，相似的塔菲尔斜率和峰值频率表明Co ²⁺ _（Td）离子主要负责水氧化催化中心。通过电化学技术和原位X射线吸收光谱，提出Fe ³⁺ _（Oh）离子主要将钴离子限制在四面体位置，以抑制尖晶石与羟基氧化物之间动态结构转变过程中钴离子的多径传递。 ，连续激活Co ²⁺ _（Td）离子的催化行为。这种与材料有关的见解为高效OER电催化剂的设计提供了指示。