One-Pot Synthesis of Ni-MOF/Co-MOF Hybrid as Electrocatalyst for Oxygen Evolution Reaction

Abstract

This approach suggests a hybrid bimetallic organic frameworks (H-biMOF) as electrocatalyst for the oxygen evolution reaction (OER) under alkaline conditions. A H-biMOF including cobalt (II) and nickel (II) was synthesized with terephthalic acid (Tp) as a linker using one-pot solvothermal method. The morphological study with microscopy techniques shows hexagonal rod-like structures for pure cobalt MOF, wood-shaving-like structures for pure nickel MOF and hexagonal nanosheets coated by wood-shaving-like structures with for H-biMOF. The structure of H-biMOF was confirmed by XRD showing both pure Co and Ni MOFs in the pattern. The catalytic OER ability of all samples was evaluated using electrochemical methods. The best performance was achieved for a H-biMOF made from a 3:1 starting salt ratio of cobalt and nickel (CoTp 3:1(Ni)). The OER catalytic activity of CoTp 3:1(Ni) demonstrates a low overpotential of 371 mV and a Tafel slope of 53.6 mV dec−1 (at a current density of 10 mA cm−2). The high catalytic activity of the biMOF through OER is related to the high number of active sites and suitable mass transport properties providing reactatnts to increase the current density at a given potential.