Three-dimensionally ordered macroporous trimetallic spinel for anion exchange membrane water electrolysis

Here, the synthesis of a NiMnCoO trimetallic catalyst with a spinel structure and three-dimensionally ordered macroporous (3DOM) morphology is reported. A polymethylmethacrylate (PMMA) template, characterized by spheres with an average diameter of 160 nm, is used in the preparation procedure. The material is investigated by X-ray diffraction, transmission and scanning electron microscopy analyzes to corroborate the incorporation of Mn and Ni into the CoO crystal structure and the formation of the 3DOM morphology, respectively. Furthermore, the sample is evaluated as an oxygen evolution reaction catalyst in an electrolyzer based on an anion exchange membrane (Fumasep® FAA3-50 from FuMaTech) as the electrolyte in different conditions. The performance is compared to that obtained using benchmarked IrO electrocatalysts. The maximum current density achieved with the developed catalyst is 2.5 A cm at 2.2 V, higher than that obtained with IrO (2 A cm at 2.2 V). Proper stability of 150 h is recorded for the cell based on the trimetallic catalyst.