468323 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.
 M.S. Burke, L.J. Enman, A.S. Batchellor, S.H. Zou, S.W. Boettcher, Oxygen evolution reaction electrocatalysis on transition metal oxides and (oxy)hydroxides: Activity trends and design principles, Chemistry of Materials, 27 (2015) 7549-7558.
 M.S. Burke, S.H. Zou, L.J. Enman, J.E. Kellon, C.A. Gabor, E. Pledger, S.W. Boettcher, Revised oxygen evolution reaction activity trends for first-row transition-metal (oxy)hydroxides in alkaline media, Journal of Physical Chemistry Letters, 6 (2015) 3737-3742.
 L. Trotochaud, S.L. Young, J.K. Ranney, S.W. Boettcher, Nickel-iron oxyhydroxide oxygen-evolution electrocatalysts: The role of intentional and incidental iron incorporation, J. Am. Chem. Soc., 136 (2014) 6744-6753.
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