Morphology-Directed Selective Production of Ethylene or Ethane from CO2on a Cu Mesopore Electrode

Article abstract of DOI:10.1002/anie.201610432

The electrocatalytic conversion of CO₂to value-added hydrocarbons is receiving significant attention as a promising way to close the broken carbon-cycle. While most metal catalysts produce C₁species, such as carbon monoxide and formate, the production of various hydrocarbons and alcohols comprising more than two carbons has been achieved using copper (Cu)-based catalysts only. Methods for producing specific C₂reduction outcomes with high selectivity, however, are not available thus far. Herein, the morphological effect of a Cu mesopore electrode on the selective production of C₂products, ethylene or ethane, is presented. Cu mesopore electrodes with precisely controlled pore widths and depths were prepared by using a thermal deposition process on anodized aluminum oxide. With this simple synthesis method, we demonstrated that C₂chemical selectivity can be tuned by systematically altering the morphology. Supported by computational simulations, we proved that nanomorphology can change the local pH and, additionally, retention time of key intermediates by confining the chemicals inside the pores.

Full text of DOI:10.1002/anie.201610432

Angewandte
Communications
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International Edition: DOI: 10.1002/anie.201610432
German Edition: DOI: 10.1002/ange.201610432
Electrocatalysis
Morphology-Directed Selective Production of Ethylene or Ethane
from CO2 on a Cu Mesopore Electrode
Ki Dong Yang+, Woo Ri Ko+, Jun Ho Lee, Sung Jae Kim, Hyomin Lee,* Min Hyung Lee,* and
Ki Tae Nam*
Abstract: The electrocatalytic conversion of CO2 to value-
added hydrocarbons is receiving significant attention as
a promising way to close the broken carbon-cycle. While
most metal catalysts produce C1 species, such as carbon
monoxide and formate, the production of various hydro-
carbons and alcohols comprising more than two carbons has
been achieved using copper (Cu)-based catalysts only. Meth-
ods for producing specific C2 reduction outcomes with high
selectivity, however, are not available thus far. Herein, the
morphological effect of a Cu mesopore electrode on the
selective production of C2 products, ethylene or ethane, is
presented. Cu mesopore electrodes with precisely controlled
pore widths and depths were prepared by using a thermal
deposition process on anodized aluminum oxide. With this
simple synthesis method, we demonstrated that C2 chemical
selectivity can be tuned by systematically altering the morphol-
ogy. Supported by computational simulations, we proved that
nanomorphology can change the local pH and, additionally,
retention time of key intermediates by confining the chemicals
inside the pores.
In particular, hydrocarbons with high energy density, like
methane (CH4) and ethane (C2H6), are compatible with
existing infrastructures and can substitute for fossil fuels.[1,2]
Additionally, hydrocarbons with unsaturated bonds are used
as major feedstocks in polymer synthesis.[3,4] For instance,
ethylene (C2H4) has carbon double bond so that it can
participate serial chain propagation reactions. Among cur-
rently available materials, Cu-based catalysts have been
reported as the only electrodes exhibiting the reduction of
CO2 to various hydrocarbons.[5–7] However, the issue of
selectivity for the conversion of CO2 to a desired hydrocarbon
remains a scientific challenge and makes its practical appli-
cation far from certain.
Several factors in product selectivity have been revealed
for CO2 reduction. According to the recent theoretical
calculations, adsorbed intermediates and their relative stabil-
ities determine the final products. Adsorbed CO is trans-
formed to COH or remains in its original form, and each
intermediate is protonated, producing CH4 or inducing CO
dimerization[8,9] In this context, control of the adsorption
energy for specific intermediates and protons involving
kinetics have been attempted by controlling the crystal
facet,[10,11] grain boundary density,[12] and oxide layer thick-
ness.[13,14] In case of C2H4 formation, the highest Faradic
efficiency of 60% is achieved by the Cu2O–Cu biphasic
electrode,[15] whereas one of 9% is observed on polycrystal-
line Cu.[10] Selective production of CH4 or C2H4 also have
been achieved on Cu nanocubes, by controlling the crystal
facet and changing proton affinity.[3]
A
s well as a major contributor of greenhouse gas, CO2 also
can be an abundant C1 feedstock. Electrochemical CO2
conversion, powered by renewable energy, has attracted
considerable attention for achieving both objectives of
reducing the carbon footprint and closing the carbon cycle.
[*] K. D. Yang,[+] J. H. Lee, Prof. K. T. Nam
Department of Materials Science and Engineering
Seoul National University
Recently, the local proton concentration was reported as
another contributor. From previous reports, observations of
length- and density-dependent product selectivity on Cu
nanowires suggested that locally high pH near the electrode
may direct the reaction towards the CO pathway, which
requires fewer protons than that of the COH pathway.[16]
Similarly, a change in the conversion efficiency for formate
(HCOOH) was observed on Cu nanofoams, depending on the
pore size and thickness.[17] However, the nanofabricated
electrodes explored to date had a high variability in size,
tortuosity, and crystal structure, so that it remains a challenge
to assess the exact role of morphology. Moreover, the possible
interplay between the morphology and retention time of
intermediates, generally observed in chromatography[18] and
drug-delivery studies,[19] has never been investigated (Sup-
porting Information, Table S1). Herein, we prepared Cu
mesopore electrode with a precisely controlled morphology,
while maintaining its physical characteristics, and studied the
effect of nanomorphology on the product selectivity. By
performing specific activity analysis and an electrohydrody-
1 Gwanak-ro, Gwanak-gu, Seoul, 08826 (Korea)
E-mail: nkitae@snu.ac.kr
W. R. Ko,[+] Prof. M. H. Lee
Department of Applied Chemistry, Kyung Hee University
Yongin, Gyeonggi 17104 (Korea)
E-mail: minhlee@khu.ac.kr
Prof. S. J. Kim
Department of Electrical and Computer Engineering, Big Data
Institute, and Inter-University Semiconductor Research Center
Seoul National University
1 Gwanak-ro, Gwanak-gu, Seoul, 08826 (Korea)
Prof. H. Lee
Department of Electrical and Computer Engineering and Institute of
Advanced Machines and Design
Seoul National University
1 Gwanak-ro, Gwanak-gu, Seoul, 08826 (Korea)
E-mail: nanofluidics@snu.ac.kr
[+] These authors contributed equally to this work.
Supporting information, including experimental details, for this
article can be found under:
http://dx.doi.org/10.1002/anie.201610432.
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Figure 1. Synthesis of the Cu mesopore electrode. a) Scheme for preparing Cu mesopore electrodes. SEM images of mesopores with b) 30 nm
width/40 nm depth (30 nm/40 nm), c) 30 nm width/70 nm depth (30 nm/70 nm), and d) 300 nm width/40 nm depth (300 nm/40 nm). Scale
bar=60 nm for (b, c) and scale bar=300 nm for (d).
namics study, we show that the change of retention times can
be directed and affect the final products.
Cu meshes with mesopores of 30 nm width and 40 nm
depth (30 nm/40 nm), 30 nm width and 70 nm depth (30 nm/
70 nm), and 300 nm width and 40 nm depth (300 nm/40 nm)
were fabricated by using a sputtering method on anodized
aluminum oxide (AAO). For their electrochemical applica-
tion, the deposited Cu meshes were transferred onto stainless
steel. The SEM images showed successful production of Cu
mesopore electrodes with uniform shapes (Figure 1 and the
Supporting Information, Figure S1). According to the XRD
analysis, all the samples exhibited similar relative intensities
for various (hkl) reflections (Supporting Information, Fig-
ure S2).
The catalytic performance of the Cu mesopore electrodes
was evaluated by linear sweep voltammetry (LSV). The onset
potential was defined as the potential required to reach
a current density of 1 mAcmꢀ2. Each current density was
normalized by the active surface area, measured by redox-
active methyl viologen (Supporting Information, Figure S3).
The series of electrodes exhibited similar catalytic activities
between ꢀ0.5 and ꢀ2.0 V. As shown in Figure 2a, the
mesopore electrodes showed average onset potentials at
ꢀ0.96 V (vs. NHE) and current densities of 14.3 mAcmꢀ2 at
ꢀ1.7 V. Although polycrystalline Cu had a similar onset
potential of ꢀ0.98 V, the observed current density at ꢀ1.7 V
was 11.8 mAcmꢀ2.
The Faradaic efficiencies of the gas products at an applied
potential of ꢀ1.7 V are presented in Figure 2. Each electrode
showed a stable current density and no change in morphology
during the reaction (Supporting Information, Figures S4 and
S5). As the pore width and depth were narrowed and
increased, respectively, the Faradaic efficiency of the C1
products steadily decreased, whereas that of the C2 products
was enhanced. Polycrystalline Cu produced mainly C1 prod-
Figure 2. Electrocatalytic CO2 reduction and hydrocarbon formation.
a) Linear sweep voltammetry curves of 30 nm/40 nm (red), 30 nm/
ucts, carbon monoxide (CO) and CH4, with a total Faradaic
efficiency of 48%, while that of the 300 nm/40 nm electrode
70 nm (blue), 300 nm/40 nm (cyan), and polycrystalline Cu (black).
b) Chemical selectivities at ꢀ1.7 V vs. NHE.
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was 18%. The rest of the current was dedicated to H2 (46%)
300 nm/40 nm electrode. Similarly, the H2-specific activities
and HCOOH (32%) (Supporting Information, Figure S9). As
the pore width was narrowed to 30 nm, the 30 nm/40 nm
electrode produced much less C1 gas products, with a Faradaic
efficiency of 19%. The Faradaic efficiency for CO slightly
increased from 2 to 5%, while that of CH4 was decreased by
more than 28%. Instead, C2H4 formation was enhanced from
8 to 38%. Interestingly, as the pore depth was increased to
70 nm, the major C2 product changed to the saturated
hydrocarbon, C2H6, with a Faradaic efficiency of 46%.
To understand the morphology dependent product dis-
tribution, CO2 and H2 specific activities were investigated
(Figure 3). In the low-potential range, below ꢀ1.5 V, CO2
were attenuated as the width and depth of pore were changed
(Figure 3b). At ꢀ1.7 V, the 300 nm/40 nm, 30 nm/40 nm and
30 nm/70 nm electrodes had H2-specific activities of 5.6, 4.3,
and 4.0 mAcmꢀ2. However, unlike the CO2-specific activities,
which showed a monotonic increase only above ꢀ1.5 V, the
H2-specific activities displayed a linear increase and pla-
teaued above ꢀ1.5 V. Note that the decline of H2 evolution
coincides with the appreciable CO2 conversion. It has been
reported that pH rises in the vicinity of the electrode owing to
OHꢀ generation at the cathode, resulting in inhibition of
proton-involving reactions.[20] Additionally, the nanomorphol-
ogy decreases the diffusion of HCO3ꢀ, which neutralizes
OHꢀ.[17,21] Taken together, morphology can affect the local
proton concentration and thereby changes the final products.
However, a selective production of C2H6 was observed from
the 30 nm/70 nm electrode, which has the lowest H2-specific
activity. Because the production of C2H6 requires two more
protons than that of C2H4, a higher local proton concentration
is naturally expected. One possible explanation is that the
intermediate species were confined and had a longer reten-
tion time to produce the saturated hydrocarbon.
To demonstrate the role of the morphology, we electro-
hydrodynamically analyzed the electrode. When the applied
voltage is above a threshold value,[22–25] the thermal fluctua-
tions of the dissolved species near the ion-selective surface
leads to chaotic vortices, which have been observed near the
cathode/anode.[26,27] Although the size of the vortex was
reported to be on the order of 1 mm (with values between
1 and 10 mm),[28,29] the speed was fast enough to affect the ionic
transportation such as ionic current, local ion concentration,
and the retention time of reactants. Mani et al.[30–33] suggested
a numerical model based on the theory of ion concentration
polarization. The electric potential and the flow fields were
governed by the Poisson equation, the Stokes equation with
the electrical body forces, and the continuity equation as
follows [Eq. (1)–(3)]:
X
2
ꢀer y ¼
Fzici,
ð1Þ
i
X
@u
@t
2
1
¼ ꢀrp þ mr u ꢀ
Fziciry
ð2Þ
ð3Þ
i
ru ¼ 0
where e is the electrical permittivity, y is the electric
potential, F is the Faraday constant, zi is the valence of i-th
species, ci is the ion concentration of i-th species, 1 is the
density, u is the flow field, t is the time, p is the hydrodynamic
pressure, and m is the dynamic viscosity. The ion trans-
portation was described by the Nernst–Planck equation
[Eqn. (4)]:
Figure 3. Electrokinetic study on the Cu mesopore electrode. Specific
activity of 30 nm/70 nm (blue), 30 nm/40 nm (red) and 300 nm/40 nm
(cyan) for a) CO2 and b) H2. Partial currents for reducing CO2 and
protons are normalized by the electrocatalytic active surface area.
conversion is kinetically hindered and no noticeable feature
was observed (Figure 3a). As higher negative potentials were
applied, each electrode exhibited clear differences. At ꢀ1.7 V,
the 300 nm/40 nm electrode showed a CO2-specific activity of
2.8 mAcmꢀ2. The 30 nm/40 nm and 30 nm/70 nm electrodes
displayed CO2-specific activities of 5.7 mAcmꢀ2 and
6.0 mAcmꢀ2, which are 2-fold higher than that of the
ꢀ
ꢁ
@ci
@t
ziFD
RT
¼ ꢀr ꢀDirci ꢀ
i ciry þ ciu
ð4Þ
where Di is the diffusivity of i-th species, R is the gas constant,
and T is the absolute temperature. Boundary conditions on
the reduction electrode (located at y = 0) were a positively
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applied voltage for the electric potential, no-slip conditions
for the flow fields, the Donnan equilibrium concentration for
the cationic species and the no-flux condition for the anionic
species [Eq. (5)],
randomly generated or diminished in both 30 nm/40 nm and
300 nm/40 nm electrodes. The local ion concentration fluc-
tuated along the chaotic vortices as well. However, the
reaction environments inside the pores were completely
different. As shown in Figure 4c, the magnitudes of the flow
velocity (that is, j u j) inside the pores were reduced as the
pore width decreased (or the pored depth increased). This
implied that the CO2 conversion inside the narrower and
deeper pore would proceed more stably. Furthermore, the
ionic species inside 30 nm-width pores was more abundant
than that in the 300 nm-width pores (Figure 4d). This was
because the electrical double layers (EDL) overlapped inside
the narrower pore and the ionic concentration was hardly
affected by the vortices. In case of the wider pore, the EDL
did not overlap; therefore, the ionic concentration was 1/100-
fold that of the bulk. Taken together, the reagents and
reaction intermediates would be trapped more often and for
longer durations inside the nanomorphology.
y ¼ Vapp, u ¼ 0, cþ ¼ N and n jꢀ ¼ 0
ð5Þ
where Vapp is the applied voltage, N is the Donnan equilibrium
concentration, n is the outward normal vector, and jꢀ is the
anion flux. Meanwhile, on the oxidation electrode (located at
y = 1 mm), the boundary conditions were grounded potential,
no-slip, and the fixed concentration [Eq. (6)],
y ¼ 0, u ¼ 0, cþ ¼ cꢀ ¼ c0
ð6Þ
where c0 is set to be the bulk concentration. The initial
conditions for the time-dependent problems were obtained by
the following steps: 1) Solving the governing equations
without the flow fields under steady-state and 2) randomly
perturbing the steady-state solutions of the ion concentration
locally by 1%, similar to Maniꢀs work.[30,31] As shown in
Figure 4a,b, the stream lines representing the electrokinetic
instability were denoted as white solid lines and were
To provide experimental evidence of the change in
retention time, we performed bulk electrolysis under a con-
trolled convective flow (Figure 5). The speed of rotation was
Figure 5. Convective effect on the CO2 reduction reaction. Catalytic
current for CO2 conversion (black) and H2 evolution (red) on the
30 nm/70 nm electrode as a function of rotation rate.
set between 0 and 1500 rpm. The 30 nm/70 nm electrode was
selected as the working electrode because it had the highest
CO2-specific activity. According to previous studies, mass
transport rarely affects the CO2 conversion reaction.[10,21]
However, unlike smooth polycrystalline Cu and other
reported metal electrodes, the 30 nm/70 nm electrode exhib-
ited a significant decrease in activity as a function of the
rotation speed. When the convective flow was not applied, the
electrode showed CO2-specific activity of 6.1 mAcmꢀ2. As the
rotation speed increased to 1500 rpm, the specific activity was
reduced to 2.9 mAcmꢀ2. Although the recorded total current
densities increased, most of the Faradaic efficiency was used
for H2 evolution. This indicates that the reaction intermedi-
ates are physically confined in the mesopore.
Figure 4. The electrokinetic instability around the electrode. Randomly
fluctuating stream lines (white solid lines) and ionic concentration
(surface plots) near the a) 30 nm/40 nm and b) 300 nm/40 nm elec-
trode. The ion concentration is shown in log scale. c) Simulated
velocity magnitudes and d) ionic concentration inside pores.
In summary, this study provides the first demonstration of
selective C2 chemical production by CO2 conversion. By using
4
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[7] H. A. Hansen, C. Shi, A. C. Lausche, A. A. Peterson, J. K.
Cu mesopores with precisely controlled size, we could
selectively convert CO2 to C2H4 or C2H6. We proposed
morphology-dependent reaction kinetics by analyzing specific
activities and performing electrohydrodynamics study.
Remarkably, morphology can affect both local pH and flow
Nørskov, Phys. Chem. Chem. Phys. 2016, 18, 9194 – 9201.
[8] F. Calle-Vallejo, M. T. M. Koper, Angew. Chem. Int. Ed. 2013, 52,
7282 – 7285; Angew. Chem. 2013, 125, 7423 – 7426.
[9] W. Luo, X. Nie, M. J. Janik, A. Asthagiri, ACS Catal. 2016, 6,
219 – 229.
ꢀ
field, accelerating the C C coupling reaction and prolonging
[10] Y. Hori, I. Takahashi, O. Koga, N. Hoshi, J. Mol. Catal. A 2003,
199, 39 – 47.
retention times. Our approach exploits a new strategy for
systematically controlling the product selectivity and reaction
kinetics of CO2 reduction.
[11] W. Zhu, Y.-J. Zhang, H. Zhang, H. Lv, Q. Li, R. Michalsky, A. A.
Peterson, S. Sun, J. Am. Chem. Soc. 2014, 136, 16132 – 16135.
[12] A. Verdaguer-Casadevall, C. W. Li, T. P. Johansson, S. B. Scott,
J. T. McKeown, M. Kumar, I. E. L. Stephens, M. W. Kanan, I.
Chorkendorff, J. Am. Chem. Soc. 2015, 137, 9808 – 9811.
[13] S. Gao, Y. Lin, X. Jiao, Y. Sun, Q. Luo, W. Zhang, D. Li, J. Yang,
Y. Xie, Nature 2016, 529, 68 – 71.
Acknowledgements
[14] D. Ren, Y. Deng, A. D. Handoko, C. S. Chen, S. Malkhandi, B. S.
Yeo, ACS Catal. 2015, 5, 2814 – 2821.
[15] H. Mistry, A. S. Varela, C. S. Bonifacio, I. Zegkinoglou, I. Sinev,
Y. Choi, K. Kisslinger, E. A. Stach, J. C. Yang, P. Strasser, et al.,
Nat. Commun. 2016, 7, 12123.
[16] M. Ma, K. Djanashvili, W. A. Smith, Angew. Chem. Int. Ed. 2016,
55, 6680 – 6684; Angew. Chem. 2016, 128, 6792 – 6796.
[17] S. Sen, D. Liu, G. T. R. Palmore, ACS Catal. 2014, 4, 3091 – 3095.
[18] S. R. Jim, A. J. Oko, M. T. Taschuk, M. J. Brett, J. Chromatogr. A
2011, 1218, 7203 – 7210.
[19] J. Li, C. Fan, H. Pei, J. Shi, Q. Huang, Adv. Mater. 2013, 25, 4386 –
4396.
[20] K. J. P. Schouten, Z. Qin, E. P. Gallent, M. T. M. Koper, J. Am.
Chem. Soc. 2012, 134, 9864 – 9867.
[21] A. S. Hall, Y. Yoon, A. Wuttig, Y. Surendranath, J. Am. Chem.
Soc. 2015, 137, 14834 – 14837.
K.D.Y., J.H.L. and K.T.N. were supported by the Global
Frontier R&D Program funded by the National Research
Foundation (2012M3A6A7054855), Korea CCS R&D Cen-
ter(Korea CCS 2020 Project) grant funded by the Ministry of
Science, ICT & Future Planning (2016M1A8A1925427) and
by the KIST Institutional Program (2E00000). W.R.K. and
M.H.L. were supported by the Basic Science Research
Program through the National Research Foundation
(2014R1A1A2058607). S.J.K. and H.L. were supported by
the
National
Research
Foundation
(2016R1A1A1A05005032) and the BK21 + program of
Creative Research Engineer Development IT, Seoul National
University. H.L. was also supported by the National Research
Foundation of Korea (2016R1A6A3A11930759).
[22] B. Zaltzman, I. Rubinstein, J. Fluid Mech. 2007, 579, 173.
[23] I. Rubinstein, B. Zaltzman, Math. Model. Methods Appl. Sci.
2001, 11, 263 – 300.
[24] I. Rubinstein, B. Zaltzman, Phys. Rev. E 2000, 62, 2238 – 2251.
[25] V. S. Pham, Z. Li, K. M. Lim, J. K. White, J. Han, Phys. Rev. E
2012, 86, 046310.
Conflict of interest
The authors declare no conflict of interest.
[26] J. Han, M. Wang, P. Bai, F. R. Brushett, M. Z. Bazant, Sci. Rep.
2016, 6, 28054.
Keywords: CO2 reduction · electrocatalysis · energy conversion ·
[27] J.-H. Han, E. Khoo, P. Bai, M. Z. Bazant, Sci. Rep. 2014, 4, 7056.
[28] Y. Green, G. Yossifon, Phys. Rev. E 2013, 87, 033005.
[29] J. C. de ValenÅa, R. M. Wagterveld, R. G. H. Lammertink, P. A.
Tsai, Phys. Rev. E 2015, 92, 031003.
nanoelectrodes
[30] C. L. Druzgalski, M. B. Andersen, A. Mani, Phys. Fluids 2013,
25, 110804.
[31] E. Karatay, C. L. Druzgalski, A. Mani, J. Colloid Interface Sci.
2015, 446, 67 – 76.
[32] S. M. Davidson, M. Wessling, A. Mani, Sci. Rep. 2016, 6, 22505.
[33] E. Karatay, M. B. Andersen, M. Wessling, A. Mani, Phys. Rev.
Lett. 2016, 116, 194501.
[1] M. Gattrell, N. Gupta, A. Co, J. Electroanal. Chem. 2006, 594, 1 –
19.
[2] K. Manthiram, B. J. Beberwyck, A. P. Alivisatos, J. Am. Chem.
Soc. 2014, 136, 13319 – 13325.
[3] F. S. Roberts, K. P. Kuhl, A. Nilsson, Angew. Chem. Int. Ed. 2015,
54, 5179 – 5182; Angew. Chem. 2015, 127, 5268 – 5271.
[4] D. Kim, S. Lee, J. D. Ocon, B. Jeong, J. K. Lee, J. Lee, Phys.
Chem. Chem. Phys. 2015, 17, 824 – 830.
[5] K. P. Kuhl, E. R. Cave, D. N. Abram, T. F. Jaramillo, Energy
Environ. Sci. 2012, 5, 7050 – 7059.
[6] P. Hirunsit, W. Soodsawang, J. Limtrakul, J. Phys. Chem. C 2015,
119, 8238 – 8249.
Manuscript received: October 25, 2016
Revised: November 15, 2016
Final Article published: && &&, &&&&
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Communications
Electrocatalysis
I pity the pore intermediate: Nanomor-
phology-directed C2-product selectivity
was demonstrated on a Cu mesopore
electrode. A local flow field is generated
on the electrode surface and confines
reaction intermediates inside the pore.
The prolonged retention time of the
intermediates affects the kinetics of pro-
K. D. Yang, W. R. Ko, J. H. Lee, S. J. Kim,
H. Lee,* M. H. Lee,*
K. T. Nam*
&&&& — &&&&
Morphology-Directed Selective
Production of Ethylene or Ethane from
CO2 on a Cu Mesopore Electrode
ꢀ
tonation and C C bond formation,
determining the final C2 product.
6
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