1 research outputs found
Cation Incorporation into Copper Oxide Lattice at Highly Oxidizing Potentials
Electrolyte cations can have significant effects on the
kinetics
and selectivity of electrocatalytic reactions. We show an atypical
mechanism through which electrolyte cations can impact electrocatalyst
performancedirect incorporation of the cation into the oxide
electrocatalyst lattice. We investigate the transformations of copper
electrodes in alkaline electrochemistry through operando X-ray absorption
spectroscopy in KOH and BaÂ(OH)2 electrolytes. In KOH electrolytes,
both the near-edge structure and extended fine-structure agree with
previous studies; however, the X-ray absorption spectra vary greatly
in BaÂ(OH)2 electrolytes. Through a combination of electronic
structure modeling, near-edge simulation, and postreaction characterization,
we propose that Ba2+ cations are directly incorporated
into the lattice and form an ordered BaCuO2 phase at potentials
more oxidizing than 200 mV vs the normal hydrogen electrode (NHE).
BaCuO2 formation is followed by further oxidation to a
bulk Cu3+-like BaxCuyOz phase at 900 mV vs
NHE. Additionally, during reduction in BaÂ(OH)2 electrolyte,
we find both Cu–O bonds and Cu–Ba scattering persist
at potentials as low as −400 mV vs NHE. To our knowledge, this
is the first evidence for direct oxidative incorporation of an electrolyte
cation into the bulk lattice to form a mixed oxide electrode. The
oxidative incorporation of electrolyte cations to form mixed oxides
could open a new route for the in situ formation of active and selective
oxidation electrocatalysts