Controlling morphology of Ni-Fe-based nanocatalysts for oxygen evolution reaction.
by Chen, Jingyi
Controlling the morphol. of nanocatalysts is a powerful approach for improving the sluggish kinetics of electrochem. reactions for many important industrial applications such as oxygen evolution reaction (OER) in water electrolysis. This work reports a scalable, oil-based method to yield highly uniform Ni-Fe-based nanocatalysts with well-defined morphol. (i.e., Ni-Fe core-shell, Ni/Fe alloy, and Fe-Ni core-shell). The Ni diffusion from the amorphous a-Ni(OH)2 core to the iron oxide shell makes the NiOx-NiOx/FeOx core-mixed shell structure the most active and the most stable nanocatalyst, which outperforms the comparison NiOx/FeOx alloy nanoparticles expected to be active for OER. Transmission electron microscopy and x-ray methods reveal that the chem. environment of the mixed NiOx/FeOx alloy compn. is important to achieve high electrocatalytic activity for OER and that the core-shell morphol. plays a key role in optimization of the electrocatalytic activity and stability of the nanocatalyst for OER. In situ x-ray absorption spectroscopy of the best-performing core-shell nanocatalysts will be discussed to illustrate the dynamics of Ni and Fe coordinate environment under the electrochem. conditions.