In situ growth of hierarchical bimetal-organic frameworks on nickel-iron foam as robust electrodes for the electrocatalytic oxygen evolution reaction.

Evidence shows that self-supported electrocatalysts are crucial role to solving environmental and energy issues. In this study, self-supported 2D metal-organic framework (MOF) nanosheets grown in situ on nickel-iron foam (NFF) were prepared by a one-step solvothermal process. The hierarchical nanostructure possesses a high specific surface area and abundant metal sites, which are beneficial for electrocatalytic reactions. In the electrocatalytic oxygen evolution reaction (OER), the optimal NiFe(20Ni)-MOF/NFF can drive current densities of 10, 50 and 100 mA cm at small overpotentials of 226, 277 and 294 mV, respectively. According to the characterization results, the OER performance is improved by the synergistic action of bimetals and the generation of hydroxides/oxyhydroxides. This work provides new insights into fabricating self-supported MOF-based electrodes for water splitting that are simple and highly efficient.