The
highly oxidized metal sites with unsaturated coordination derived
from in situ electrochemical reconstruction combined with the dynamic
adaptive surface geometry construction of the catalyst are of the
utmost importance to enhance the intrinsic activity of the catalysts
for oxygen evolution reaction (OER). Although the dynamic phase reconfiguration
of catalysts during the OER process has been widely observed, the
reconfigured active phase is only limited to the unitary metallic
(oxygen) hydroxides. Here, we reveal the dynamic evolution of the
local geometry and electronic structure of nickel–iron carbonate
hydroxide hydrate (NFCH) electrodes under oxidation potential. The
results show that, in the early stage of cyclic voltammetry (CV) cycles,
the irreversible redox of Ni cations will lead to the phase transition
of the porous NF-CH-O nanosheets (nickel ferrite (NFO) intercalated
nickel–iron carbonate hydroxide hydrate), thus forming an intact
NiFe layered double hydroxide (NF-LDH-O) nanosheets with high surface
roughness, which has excellent OER catalytic activity and stability.
The theoretical model indicates that the high-oxidation-state metal
sites with unsaturated coordination formed by the electron transfer
facilitated by the electronic coupling of nickel and iron (Ni–O–Fe
bond) in the LDH phase can form appropriate bonds with the adsorbed
oxygen species, thus accelerating the reaction rate and improving
the OER activity of the NF-LDH-O catalyst. These discoveries not only
clarify the electrochemical sensitivity of the NiFe-based carbonate
hydroxide under oxidation conditions but also present an electrochemical
coordination–engineering tactic for the rational design of
high-active performance catalysts. This methodology for designing
the high-performance electrocatalyst for renewable energy applications
should be extended to other layered double hydroxide materials with
different metal cations or interlayer anions.
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