Abstract First-row transition metal compounds have been widely explored as oxygen evolution reaction (OER) electrocatalysts due to their impressive performance in this application. However, the activity trends of these electrocatalysts remain elusive due to the effect of inevitable iron impurities in alkaline electrolytes on the OER; the inhomogeneous structure of iron-based (oxy)hydroxides further complicates this situation. Bimetallic metal-organic frameworks (MOFs) have the advantages of well-defined and uniform atomic structures and the tunable coordination environments, allowing the structure-activity relationships of bimetallic sites to be precisely explored. Therefore, we prepared a series of iron-based bimetallic MOFs (denoted as Fe2M-MIL-88B, M = Mn, Co, or Ni) and systematically compared their electrocatalytic performance in the OER in this work. All the bimetallic MOFs exhibited higher OER activity than their monometallic iron-based counterpart, with their activity following the order FeNi > FeCo > FeMn. In an alkaline electrolyte, Fe2Ni-MIL-88B showed the lowest overpotential to achieve a current density of 10 mA cm−2 (307 mV) and the smallest Tafel slope (38 mV dec−1). The experimental and calculated results demonstrated that iron and nickel exhibited the strongest coupling effect in the series, leading to modification of the electronic structure, which is crucial for tuning the electrocatalytic activity.

中文翻译：

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铁基二元金属有机骨架纳米棒作为析氧反应的有效催化剂

摘要 第一排过渡金属化合物因其在该应用中令人印象深刻的性能而被广泛用作析氧反应 (OER) 电催化剂。然而，由于碱性电解质中不可避免的铁杂质对 OER 的影响，这些电催化剂的活性趋势仍然难以捉摸。铁基（羟基）氢氧化物的不均匀结构使这种情况进一​​步复杂化。双金属金属有机骨架（MOFs）具有原子结构明确、均匀、配位环境可调的优点，可以精确探索双金属位点的构效关系。因此，我们制备了一系列铁基双金属 MOFs（表示为 Fe2M-MIL-88B，M = Mn，Co，或 Ni) 并在这项工作中系统地比较了它们在 OER 中的电催化性能。所有双金属 MOF 都表现出比单金属铁基对应物更高的 OER 活性，它们的活性顺序为 FeNi > FeCo > FeMn。在碱性电解质中，Fe2Ni-MIL-88B 显示出最低的过电位，可实现 10 mA cm-2 (307 mV) 的电流密度和最小的 Tafel 斜率 (38 mV dec-1)。实验和计算结果表明，铁和镍在该系列中表现出最强的耦合效应，导致电子结构的改变，这对于调节电催化活性至关重要。在碱性电解质中，Fe2Ni-MIL-88B 显示出最低的过电位，可实现 10 mA cm-2 (307 mV) 的电流密度和最小的 Tafel 斜率 (38 mV dec-1)。实验和计算结果表明，铁和镍在该系列中表现出最强的耦合效应，导致电子结构的改变，这对于调节电催化活性至关重要。在碱性电解质中，Fe2Ni-MIL-88B 显示出最低的过电位，可实现 10 mA cm-2 (307 mV) 的电流密度和最小的 Tafel 斜率 (38 mV dec-1)。实验和计算结果表明，铁和镍在该系列中表现出最强的耦合效应，导致电子结构的改变，这对于调节电催化活性至关重要。