Electrocatalysis of Ethanol on a Pd Electrode in Alkaline
Media: An <i>in Situ</i> Attenuated Total Reflection Surface-Enhanced
Infrared Absorption Spectroscopy Study
Yao-Yue Yang
Jie Ren
Qiao-Xia Li
Zhi-You Zhou
Shi-Gang Sun
Wen-Bin Cai
10.1021/cs401198t.s001
https://acs.figshare.com/articles/journal_contribution/Electrocatalysis_of_Ethanol_on_a_Pd_Electrode_in_Alkaline_Media_An_i_in_Situ_i_Attenuated_Total_Reflection_Surface_Enhanced_Infrared_Absorption_Spectroscopy_Study/2029713
<i>In situ</i> attenuated
total reflection surface-enhanced
infrared absorption spectroscopy in conjunction with H–D isotope
replacement is used to investigate the dissociation and oxidation
of CH<sub>3</sub>CH<sub>2</sub>OH on a Pd electrode in 0.1 M NaOH,
with a focus on identifying the chemical nature of the pivotal intermediate
in the so-called dual-pathway (C1 and C2) reaction mechanism. Real-time
spectroelectrochemical measurements reveal a band at ∼1625
cm<sup>–1</sup> showing up prior to the multiply bonded CO<sub>ad</sub> band. CH<sub>3</sub>CD<sub>2</sub>OH and D<sub>2</sub>O
are used to exclude the spectral interference with this band from
interfacial acetaldehyde and H<sub>2</sub>O, respectively, confirming
for the first time that the ∼1625 cm<sup>–1</sup> band
is due to the adsorbed acetyl on the Pd electrode in alkaline media.
The spectral results suggest that the as-adsorbed acetyl (CH<sub>3</sub>CO<sub>ad</sub>) is oxidized to acetate from approximately −0.4
V as the potential moves positively to conclude the C2 pathway. Alternatively,
in the C1 pathway, the CH<sub>3</sub>CO<sub>ad</sub> is decomposed
to α-CO<sub>ad</sub> and β-CH<sub><i>x</i></sub> species on the Pd electrode at potentials more negative than approximately
−0.1 V; the α-CO<sub>ad</sub> species is oxidized to
CO<sub>2</sub> at potentials more positive than approximately −0.3
V, while the β-CH<sub><i>x</i></sub> species may be
first converted to CO<sub>ad</sub> at approximately −0.1 V
and further oxidized to CO<sub>2</sub> at more positive potentials.
2015-12-17 00:56:08
3CH
3CD
2O
Pd electrode
CH 3COad
CHx
C 2 pathway
CO 2
cm
Absorption Spectroscopy StudyIn
C 1 pathway
species
potential
acetyl
0.1 M NaOH