(561d) Iron-Doped Nickel Catalysts as Anode Materials for An Electrochemical Air Separation Device

Oxy-fired coal plants as well as integrated gasification combined cycle plants are of interest for their use in capturing carbon dioxide. The production of pure oxygen from the air is essential as a source for these plants. Currently, the technology used to accomplish this air separation process is cryogenic refrigeration. This method is energy intensive and requires a large capital cost. Various other technologies are being proposed to perform this task. One possible route to separate oxygen from the air would be through the use of an electrochemical oxygen concentration cell. These cells can theoretically run with low energy requirements. However, to make this technology viable and approach these low energy costs, catalyst development in the form of more active oxygen reduction and evolution catalysts is necessary. This research investigates more active transition metal oxide catalysts for oxygen evolution. Iron-doped nickel powders were synthesized through an evaporation-induced self-assembly process (EISA) yielding catalysts with BET surface areas ranging from 15-35 m²/g. Catalysts with doping between 3-10mol% Fe were examined through cyclic voltammetry (CV) and chronoamperometry (CA). It was found that by doping nickel with 5mol% iron, large catalytic gains could be realized. At a modest overpotential of 0.6V, activity of this doped catalyst was increased by 300% over pure nickel oxide. XRD examination of these iron doped catalysts revealed crystalline NiO with no change in the lattice constant suggesting substitutional incorporation of iron into the nickel lattice. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis of the electrode surface further showed a well dispersed nickel-iron catalyst. Finally, these catalysts were incorporated into an air separation cell showing successful oxygen separation at potentials lower than 1 V.