Impact of nanoparticle size and lattice oxygen on water oxidation on NiFeOxHy
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NiFeOxHy are the most active catalysts for oxygen evolution in a base. For this reason, they are used widely in alkaline electrolysers. Several open questions remain as to the reason for their exceptionally high catalytic activity. Here we use a model system of mass-selected NiFe nanoparticles and isotope labelling experiments to show that oxygen evolution in 1 M KOH does not proceed via lattice exchange. We complement our activity measurements with electrochemistry–mass spectrometry, taken under operando conditions, and transmission electron microscopy and low-energy ion-scattering spectroscopy, taken ex situ. Together with the trends in particle size, the isotope results indicate that oxygen evolution is limited to the near-surface region. Using the surface area of the particles, we determined that the turnover frequency was 6.2 ± 1.6 s−1 at an overpotential of 0.3 V, which is, to the best of our knowledge, the highest reported for oxygen evolution in alkaline solution.
Roy, C., Sebok, B., Scott, B., Fiordaliso, E. M., Sørensen, J. E., Bodin, A., Trimarco, D. B., Damsgaard, C. D., Vesborg, P. C. K., Hansen, O., Stephens, I. E. L., Kibsgaard, J., & Chorkendorff, I. (2018). Impact of nanoparticle size and lattice oxygen on water oxidation on NiFeOxHy. Nature Catalysis, 1(11), 820-829. https://doi.org/10.1038/s41929-018-0162-x