The development of metal–organic frameworks (MOFs) as high-efficiency electrocatalysts for water splitting has attracted special attention due to their unique structural features including high porosity, large surface areas, high concentrations of active sites, uniform pore sizes and shapes, etc. Most of the related reports focus on the in situ generation of high-efficiency electrocatalysts by annealed MOFs. However, the pyrolysis process usually destroys the porous structure of MOFs and reduces the number of active sites due to the absence of organic ligands and agglomeration of metal centers. In this work, we prepared unique NiCo-MOF hollow nanospheres (NiCo-MOF HNSs) by a solvothermal method and further fabricated Fe-doped NiCo-MOF HNSs (Fe@NiCo-MOF HNSs) by a simple impregnation-drying method. Significant enhancement of electrocatalytic activity of Fe@NiCo-MOF HNSs was witnessed because of the doped Fe. Compared with the parent NiCo-MOF HNSs, the optimized Fe@NiCo-MOF HNSs exhibited a lower overpotential of 244 mV at 10 mA·cm⁻² with a smaller Tafel slope of 48.61 mV·dec⁻¹, which was lowered by ca. 90 mV due to the influence of Fe doping on the electronic structure of the active centers of Ni and Co. The above materials also displayed excellent stability without obvious activity decay for at least 16 hours. These findings present a new entry in the design and fabrication of high-efficiency MOF-based electrocatalysts for energy conversion.

中文翻译：

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铁掺杂的NiCo-MOF空心纳米球可增强电催化氧的释放。

金属有机骨架（MOFs）作为高效的水分解电催化剂的开发由于其独特的结构特征（包括高孔隙率，大表面积，高活性位点浓度，均匀的孔径和形状等）而引起了人们的特别关注。大多数相关报告都集中在原地退火MOF生成高效电催化剂。但是，由于缺乏有机配体和金属中心的团聚，热解过程通常会破坏MOF的多孔结构并减少活性位点的数量。在这项工作中，我们通过溶剂热法制备了独特的NiCo-MOF中空纳米球（NiCo-MOF HNSs），并通过简单的浸渍干燥方法进一步制备了掺铁的NiCo-MOF HNSs（Fe @ NiCo-MOF HNSs）。由于掺杂了Fe，因此观察到Fe @ NiCo-MOF HNS的电催化活性显着增强。与母体NiCo-MOF HNS相比，优化的Fe @ NiCo-MOF HNS在10 mA·cm ^-2时显示出较低的244 mV过电位，而Tafel斜率更小，为48.61 mV·dec ^-1，降低了约ca。由于Fe掺杂对Ni和Co活性中心的电子结构的影响而产生的90 mV电压。上述材料还显示了出色的稳定性，至少16小时没有明显的活性衰减。这些发现为高效的基于MOF的电能转化电催化剂的设计和制造提供了新的机会。