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Alkaline anion exchange membrane electrolyzers have high potential to support renewable energy systems through energy storage in the form of hydrogen. However, the efficiency of these electrolyzers is significantly hindered by the sluggish kinetics of the oxygen evolution reaction (OER). High overpotentials are needed to overcome this kinetic hinderance, which translates to higher energy requirements for water electrolysis. Effective electrocatalysts can lower the overpotential for OER and water electrolysis, but these catalysts need to be highly active, stable, and inexpensive. The most active catalysts for OER are IrO_x and RuO_x; however, these catalysts contain precious transition metals that are prohibitively costly to deploy on a large scale. Nickel-Iron oxide catalysts (NiFeO_x) are non-precious alternatives for OER catalysis, which have shown higher activity than IrO_x in alkaline conditions. However, the long-term stability of these NiFeO_x has not been adequately demonstrated to date.

We have synthesized carbon-supported NiFeO_x nanoparticles using a straightforward wet impregnation method. This catalyst can achieve 10 mA/cm² at 300 mV overpotential at room temperature and at 240 mV at 70°C in alkaline aqueous solution. The stability of this catalyst, however, is poor in concentrated alkaline electrolytes. Thus, we are working to determine the cause of instability in this catalyst. Our working hypothesis is that the poor stability results primarily from oxidative degradation of the carbon support. We have evaluated this hypothesis by integrating accelerated degradation electrochemistry experiments with detailed materials analysis techniques, including SEM, XRD, and Raman Microscopy.