Fe/Ni bimetal organic framework as efficient oxygen evolution catalyst with low overpotential.

Electrochemical water-splitting is an ideal strategy to produce the promising substitutable energy source, hydrogen (H2). However, the sluggish kinetics of electrochemical oxygen evolution reaction (OER) and the prohibitive cost, low reserves and easy oxidation of noble metal-based electrocatalysts force researchers to explore efficient and low-cost electrocatalysts. Bimetal nanostructred materials are proved to have enhanced OER catalytic performances. In this study, a series of bimetallic metal-organic frameworks (Fe/Ni-MOFs) are prepared by a solvothermal method. The prepared MOFs present abundant unsaturated metal active sites for OER. The optimized Fe/Ni bimetal-MOF has low overpotentials of 236 mV at 10 mA cm-2 and 284 mV at 100 mA cm-2 for OER. In addition, in comparison with most of the previously reported OER electrocatalysts, the present MOF shows a lower Tafel slope of 49 mV dec-1. Besides, the MOF catalyst exhibits high electrochemical stability and the OER activity shows a negligible change after stability test for 15 h and 10,000 voltammetric cycles. Meanwhile, the Fe-doped Ni-MOFs show faster catalytic kinetics and higher conductivity than the monometallic Ni-MOF. This work paves a way to exploit bi- or multi-metallic MOFs with high conductivities and electrocatalytic performances for electrochemical energy conversion.