58 research outputs found
Electrochemical oxidation of CO on Cu single crystals under alkaline conditions
We perform a joint experimental-theoretical study of the electrochemical
oxidation of CO on copper (Cu) under alkaline conditions. Using cyclic
voltammetry on Cu single crystal surfaces, we demonstrate that both Cu terraces
and steps show CO oxidation activity at potentials just slightly positive
(0.03-0.14 V) of the thermodynamic equilibrium potential. The overpotentials
are 0.23-0.12 V lower than that of gold (approx. 0.26 V), which up until now
has been considered to be the most active catalyst for this process. Our
theoretical calculations suggest that Cu's activity arises from the
advantageous combination of simultaneous *OH adsorption under CO oxidation
potentials and surmountable *CO-*OH coupling barriers. Experimentally observed
onset potentials are in agreement with the computed onsets of *OH adsorption.
We furthermore show that the onsets of *OH adsorption on steps are more
affected by *CO-*OH interactions than on terraces due to a stronger competitive
adsorption. Overall, Cu(100) shows the lowest overpotential (0.03 V) of the
facets considered.Comment: 16 pages, 3 figures plus supplementary informatio
Progress and Perspectives of Electrochemical CO<sub>2</sub> Reduction on Copper in Aqueous Electrolyte
To date, copper is
the only heterogeneous catalyst that has shown
a propensity to produce valuable hydrocarbons and alcohols, such as
ethylene and ethanol, from electrochemical CO2 reduction
(CO2R). There are variety of factors that impact CO2R activity and selectivity, including the catalyst surface
structure, morphology, composition, the choice of electrolyte ions
and pH, and the electrochemical cell design. Many of these factors
are often intertwined, which can complicate catalyst discovery and
design efforts. Here we take a broad and historical view of these
different aspects and their complex interplay in CO2R catalysis
on Cu, with the purpose of providing new insights, critical evaluations,
and guidance to the field with regard to research directions and best
practices. First, we describe the various experimental probes and
complementary theoretical methods that have been used to discern the
mechanisms by which products are formed, and next we present our current
understanding of the complex reaction networks for CO2R
on Cu. We then analyze two key methods that have been used in attempts
to alter the activity and selectivity of Cu: nanostructuring and the
formation of bimetallic electrodes. Finally, we offer some perspectives
on the future outlook for electrochemical CO2R
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