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要旨:
Sub-10 nm CoFe2O4 nanoparticles with different sizes and various
compositions obtained by (partial) substitution of Co with Ni cations have been synthesized by using a one-pot method
from organic solutions by the decomposition of metal acetylacetonates in the presence of oleylamine. The electrocatalytic activity of CoFe2O4 towards the oxygen evolution reaction
(OER) is clearly enhanced with a smaller size (3.1 nm) of the
CoFe2O4 nanoparticles (compared with 4.5 and 5.9 nm). In addition, the catalytic activity is improved by partial substitution
of Co with Ni, which also leads to a higher degree of inversion of the spinel structure. Theoretical calculations attribute the
positive catalytic effect of Ni owing to the lower binding energy differences between adsorbed O and OH compared with pure cobalt or nickel ferrites, resulting in higher OER activity. Co0.5Ni0.5Fe2O4 exhibited a low overpotential of approximately
340 mV at 10 mAcm-2, a smaller Tafel slope of 51 mVdec-1, and stability over 30 h. The unique tunability of these CoFe2O4 nanocrystals provides great potential for their application as an efficient and competitive anode material in the field of electrochemical water splitting as well as for systematic fundamental studies aiming at understanding the correlation of composition and structure with performance in electrocatalysis.
