A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction (OER) during the water oxidation process. In particular, Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity. However, the critical role of Fe species during the electrocatalytic process is still under evaluation. Herein, we report nickel (oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework (NiFe-MOF) during the water oxidation process. The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni⁴⁺, which directly correlates with an enhanced OER activity. Both the geometric and electronic structures of the as-reconstructed Ni_1−xFe_xOOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF, further affecting the catalytic activity. As a result, the Ni_1−xFe_xOOH derived from Ni_0.9Fe_0.1-MOF delivers low overpotentials of 260 mV at 10 mA cm⁻² and 400 mV at 300 mA cm⁻².

Ni和Fe氧化物的混合物是水氧化过程中析氧反应（OER）最常用的活性催化剂之一。特别是，即使掺入少量Fe的Ni氧化物也会显着提高OER活性。然而，Fe 物种在电催化过程中的关键作用仍在评估中。在此，我们报告了在水氧化过程中通过双金属金属有机骨架 (NiFe-MOF) 的表面重建与 Fe 结合的镍（氧）氢氧化物。光谱研究与理论计算揭示了 Fe 在促进高氧化 Ni ^{4+形成中的关键作用}，这与增强的 OER 活性直接相关。_{重构后的 Ni 1 - x} Fe _x OOH 电催化剂的几何结构和电子结构都可以通过双金属 NiFe-MOF 的 Ni-Fe 比进行微调，从而进一步影响催化活性。结果，源自Ni _0.9 Fe _{0.1 -MOF的Ni 1- x} Fe _x ^{OOH 在10 mA cm -2}和300 mA cm ^-2提供260 mV的低过电势和400 mV 。