(348d) Fe-Ni Core-Shell Hydroxide Nanoparticles As an Active Oxygen Evolution Reaction (OER) Catalyst
In this presentation, our results on the synthesis, characterization, and electrochemical testing of an iron-nickel core-shell hydroxide nanoparticle catalyst will be presented. Bimetallic iron-nickel nanoparticles were synthesized using a multi-step procedure in water under ambient conditions. When compared to monometallic iron and nickel nanoparticles, the Fe-Ni nanoparticles show enhanced catalytic activity for OER under alkaline conditions (1 M NaOH). The bimetallic nanoparticles demonstrated an improvement in OER overpotential as well as a significant increase in maximum measured current density, as compared to the monometallic iron and nickel nanoparticles. At 1 mA/cm2, the overpotential for the monometallic iron and nickel nanoparticles was 421 mV and 476 mV, respectively, while the bimetallic Fe-Ni nanoparticles had a greatly reduced overpotential of only 256 mV. At 10 mA/cm2, bimetallic Fe-Ni nanoparticles had an overpotential of 311 mV. Electron microscopy and elemental analysis results will be presented with a detailed discussion of unique aspects of the FeNi nanoparticle catalyst. Results suggest that while the nanoparticles are nominally in a core-shell morphology, there is significant migration of iron into the nickel shell as well as incorporation of some phosphorus into the nanoparticle shell, likely originating from the phosphonate-based stabilizer used during nanoparticle synthesis. X-ray photoelectron spectroscopy suggests that the primary phase of nickel is nickel hydroxide, and x-ray absorption spectroscopy characterization suggests that the primary phase of nickel is the more disordered alpha phase of nickel hydroxide. The presence of a small amount of nickel (oxy)hydroxide is also likely present, based on characterization results.
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