1 research outputs found
Iron-Induced Activation of Ordered Mesoporous Nickel Cobalt Oxide Electrocatalyst for the Oxygen Evolution Reaction
Herein, ordered mesoporous
nickel cobalt oxides prepared by the
nanocasting route are reported as highly active oxygen evolution reaction
(OER) catalysts. By using the ordered mesoporous structure as a model
system and afterward elevating the optimal catalysts composition,
it is shown that, with a simple electrochemical activation step, the
performance of nickel cobalt oxide can be significantly enhanced.
The electrochemical impedance spectroscopy results indicated that
charge transfer resistance increases for Co<sub>3</sub>O<sub>4</sub> spinel after an activation process, while this value drops for NiO
and especially for CoNi mixed oxide significantly, which confirms
the improvement of oxygen evolution kinetics. The catalyst with the
optimal composition (Co/Ni 4/1) reaches a current density of 10 mA/cm<sup>2</sup> with an overpotential of a mere 336 mV and a Tafel slope
of 36 mV/dec, outperforming benchmarked and other reported Ni/Co-based
OER electrocatalysts. The catalyst also demonstrates outstanding durability
for 14 h and maintained the ordered mesoporous structure. The cyclic
voltammograms along with the electrochemical measurements in Fe-free
KOH electrolyte suggest that the activity boost is attributed to the
generation of surface NiÂ(OH)<sub>2</sub> species that incorporate
Fe impurities from the electrolyte. The incorporation of Fe into the
structure is also confirmed by inductively coupled plasma optical
emission spectrometry