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

Here, the synthesis of a Ni0.5Mn0.5Co2O4 trimetallic catalyst with a spinel structure and three-dimensionally ordered macroporous (3DOM) morphology is reported. A polymethylmethacrylate (PMMA) template, charac-terized 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 Co3O4 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 & REG; FAA3-50 from FuMaTech) as the electrolyte in different conditions. The performance is compared to that obtained using benchmarked IrO2 electrocatalysts. The maximum current density achieved with the developed catalyst is 2.5 A cm-2 at 2.2 V, higher than that obtained with IrO2 (2 A cm-2 at 2.2 V). Proper stability of 150 h is recorded for the cell based on the trimetallic catalyst.