Bifunctional electrocatalysts for oxygen reduction/evolution reactions derived from NiCoFe LDH materials

Materials obtained from thermal treatment of thermally treated NiCoFe-layered double hydroxides (LDH) with different Ni:Co ratios were evaluated as bifunctional catalysts for Oxygen Reduction Evolution and Evolution Reduction Reactions in alkaline media. The structural properties of synthesized materials were characterized by X-ray diffraction, Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopies, whereas the basicity of each material was evaluated by temperature-programmed desorption of carbon dioxide. The results revealed the presence of inverse spinel structure with different compositions and a NiO phase with different amounts in the sample, while the electrochemical results showed a high activity towards oxygen reactions. The sample with higher amount of NiO and the lowest substitution grade on tetrahedral sites in the spinel-type structure exhibited the best catalytic activity. Graphical Abstract