Trimetallic Co-Ni-Mn metal-organic framework as an efficient electrocatalyst for alkaline oxygen evolution reaction

•CoNi-, CoMn-, and CoNiMn-MOF were synthesized via a facile hydrothermal route.•CoNiMn-MOF exhibited the highest electrocatalytic activity toward OER.•A η20 of 220 mV and a Tafel slope of 66 mV dec−1 were measured for CoNiMn-MOF.•CoNiMn-MOF displayed excellent electrochemical stability for 20 h. Designing efficient and inexpensive catalysts toward the oxygen evolution reaction (OER) is vital for achieving sustainable and green hydrogen fuel production through water electrolysis. Herein, we have synthesized several bi- and trimetallic metal–organic frameworks (MOFs) composed of Co, Ni, and Mn metals and benzene-1,3,5-tricarboxylic acid linker. The MOFs were prepared via a simple hydrothermal method, and their electrocatalytic performances in alkaline OER were investigated. A battery of analytical techniques was employed to characterize the as-synthesized materials, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and nitrogen adsorption–desorption analysis. It was found that the trimetallic CoNiMn-MOF exhibits the highest electrocatalytic activity in OER, with an overpotential of 220 mV at the current density of 20 mA cm−2, a Tafel slope of 66 mV dec−1, and a very good electrochemical stability for 20 h. Remarkably, this trimetallic MOF can deliver a high current density of 250 mA cm−2 at an overpotential of only 293 mV. These findings indicate the great potential of CoNiMn-MOF as a high-performance and cost-effective catalyst for the electrochemical oxidation of water.