Iron-doped NiCo-MOF hollow nanospheres for enhanced electrocatalytic oxygen evolution.

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