Great efforts in developing bifunctional water splitting electrocatalysts are to construct catalytic materials with new and optimized chemical compositions and structures for enhancing efficiency of both anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). In this work, the Fe-doped NiO mesoporous nanosheets array on Ni foam with different Fe dopant content (Fe_x%-NiO/NF) was synthesized by a facile solvothermal synthesis in mixed solvents of deionized water and methanol and subsequent anneal in air. The well-connected three-dimensional mesoporous nanosheets array structure offers a large number of catalytically active sites and buffers the large volume change during the electrochemical process of OER and HER. More importantly, the doped Fe³⁺ ions modified atomic and electronic structure of NiO by activated Ni centers through a Fe-induced partial-charge-transfer process which can promote the electrocatalytic performances of NiO for OER and HER. As a result, the optimized Fe_11%-NiO/NF electrode exhibited excellent OER activity with a small overpotential of 206 mV at 10 mA cm⁻² and a low Tafel slope of 49.4 mV dec⁻¹. Moreover, it also presented prominent HER activity, only demanding a small overpotential of 88 mV at 10 mA cm⁻² and a low Tafel slope of 49.7 mV dec⁻¹. A two-electrode electrolyzer using Fe_11%-NiO/NF as both anode and cathode performs active overall water splitting, needing a small cell voltage of 1.579 V to afford a current density of 10 mA cm⁻². This work can stimulate the design and optimization of Ni-Fe mixed oxide as an efficient electrocatalyst for practical overall water electrolysis.

开发双功能水分解电催化剂的巨大努力是构建具有新的和优化的化学组成和结构的催化材料，以提高阳极氧气逸出反应（OER）和阴极氢气逸出反应（HER）的效率。在这项工作中，通过在去离子水和甲醇的混合溶剂中轻松地溶剂热合成并随后在空气中进行退火，合成了具有不同Fe掺杂含量（Fe _x％ -NiO / NF）的Ni泡沫上的Fe掺杂NiO介孔纳米片阵列。良好连接的三维介孔纳米片阵列结构可提供大量的催化活性位点，并在OER和HER的电化学过程中缓冲大量的体积变化。更重要的是，掺杂的Fe ³⁺离子通过活化的Ni修饰NiO的原子和电子结构，这是通过Fe诱导的部分电荷转移过程实现的，该过程可以促进NiO对OER和HER的电催化性能。结果，优化的Fe _11％ -NiO / NF电极表现出优异的OER活性，在10 mA cm ^-2时的过电势较小，为206 mV，Tafel斜率较低，为49.4 mV dec ^-1。此外，它还表现出显着的HER活性，仅要求在10 mA cm ^-2时有88 mV的小过电位和49.7 mV dec ^-1的低Tafel斜率。使用Fe _11％的两电极电解槽-NiO / NF既作为阳极又作为阴极执行主动的总水分解，需要1.579 V的小电池电压来提供10 mA cm ^-2的电流密度。这项工作可以刺激Ni-Fe混合氧化物的设计和优化，以作为一种实用的整体水电解的有效电催化剂。