Oxalate-coordinated transition metal-based electrocatalysts
have
recently been shown to be very efficient for oxygen evolution reaction
(OER). However, the role of oxalate ligands has not been fully revealed.
Here, the effect of oxalate ligands with two −COO functional
groups on the surface of bimetallic sulfides is revealed. Through
ex situ Fourier transform infrared, X-ray diffraction, X-ray photoelectron
spectroscopy, and other material characterization techniques and in
situ electrochemical characterization techniques, it is proved that
the suitable oxalate-coordinated FeNi bimetallic sulfide (Fe–Ni3S2/OXs) has the best OER catalytic activity, which
can be attributed to the synergistic effect of the high-valence metal
sites and the proton center of the carboxyl functional group in oxalate.
The results of the density functional theory calculation show that
oxalate coordination can effectively optimize the adsorption–dissociation
performance of the catalyst surface for OH– and
provide a proton adsorption center, thereby promoting the Gibbs’s
free energy of reaction intermediates. And the overpotential of 260
mV (90% IR) is observed at the geometric current density of 100 mA
cm–2 in 1 M KOH solution, and the catalytic performance
of OER is proved to be strongly associated with the oxalate-coordinated
concentration on the support surface. And its Tafel slope reaches
57 mV dec–1, which has excellent OER catalytic reaction
kinetics. This work reveals the effect of oxalate ligands on OER activity
and provides a promising way for the preparation of efficient basic
oxygen evolution electrocatalysts.