pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper

Xinyan Liu; Philomena Schlexer; Jianping Xiao; Yongfei Ji; Lei Wang; Robert B. Sandberg; Michael Tang; Kristopher S. Brown; Hongjie Peng; Stefan Ringe; Christopher Hahn; Thomas F. Jaramillo; Jens K. Nørskov; Karen Chan

doi:10.1038/s41467-018-07970-9

pH effects on the electrochemical reduction of CO₍₂₎ towards C₂ products on stepped copper

Xinyan Liu, Philomena Schlexer, Jianping Xiao, Yongfei Ji, Lei Wang, Robert B. Sandberg, Michael Tang, Kristopher S. Brown, Hongjie Peng, Stefan Ringe, Christopher Hahn, Thomas F. Jaramillo, Jens K. Nørskov, Karen Chan^*

^*Corresponding author for this work

Department of Physics

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Abstract

We present a microkinetic model for CO₍₂₎ reduction (CO₍₂₎R) on Cu(211) towards C₂ products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C₁ vs C₂ activity arise from differences in their multi-step mechanisms. We find the depletion in C₂ products observed at high overpotential and high pH to arise from the 2nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C₁ pathway. We further demonstrate that CO₍₂₎ reduction at a fixed pH yield similar activities, due to the facile kinetics for CO₂ reduction to CO on Cu, which suggests C₂ products to be favored for CO₂R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C₂ products.

Original language	English
Article number	32
Journal	Nature Communications
Volume	10
Issue number	1
Number of pages	9
ISSN	2041-1723
DOIs	https://doi.org/10.1038/s41467-018-07970-9
Publication status	Published - 2019

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@article{f7526c6e872048e097f0a35174d10b68,

title = "pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper",

abstract = "We present a microkinetic model for CO(2) reduction (CO(2)R) on Cu(211) towards C2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C1 vs C2 activity arise from differences in their multi-step mechanisms. We find the depletion in C2 products observed at high overpotential and high pH to arise from the 2nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C1 pathway. We further demonstrate that CO(2) reduction at a fixed pH yield similar activities, due to the facile kinetics for CO2 reduction to CO on Cu, which suggests C2 products to be favored for CO2R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C2 products.",

author = "Xinyan Liu and Philomena Schlexer and Jianping Xiao and Yongfei Ji and Lei Wang and Sandberg, {Robert B.} and Michael Tang and Brown, {Kristopher S.} and Hongjie Peng and Stefan Ringe and Christopher Hahn and Jaramillo, {Thomas F.} and N{\o}rskov, {Jens K.} and Karen Chan",

year = "2019",

doi = "10.1038/s41467-018-07970-9",

language = "English",

volume = "10",

journal = "Nature Communications",

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TY - JOUR

T1 - pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper

AU - Liu, Xinyan

AU - Schlexer, Philomena

AU - Xiao, Jianping

AU - Ji, Yongfei

AU - Wang, Lei

AU - Sandberg, Robert B.

AU - Tang, Michael

AU - Brown, Kristopher S.

AU - Peng, Hongjie

AU - Ringe, Stefan

AU - Hahn, Christopher

AU - Jaramillo, Thomas F.

AU - Nørskov, Jens K.

AU - Chan, Karen

PY - 2019

Y1 - 2019

N2 - We present a microkinetic model for CO(2) reduction (CO(2)R) on Cu(211) towards C2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C1 vs C2 activity arise from differences in their multi-step mechanisms. We find the depletion in C2 products observed at high overpotential and high pH to arise from the 2nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C1 pathway. We further demonstrate that CO(2) reduction at a fixed pH yield similar activities, due to the facile kinetics for CO2 reduction to CO on Cu, which suggests C2 products to be favored for CO2R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C2 products.

AB - We present a microkinetic model for CO(2) reduction (CO(2)R) on Cu(211) towards C2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C1 vs C2 activity arise from differences in their multi-step mechanisms. We find the depletion in C2 products observed at high overpotential and high pH to arise from the 2nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C1 pathway. We further demonstrate that CO(2) reduction at a fixed pH yield similar activities, due to the facile kinetics for CO2 reduction to CO on Cu, which suggests C2 products to be favored for CO2R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C2 products.

U2 - 10.1038/s41467-018-07970-9

DO - 10.1038/s41467-018-07970-9

M3 - Journal article

C2 - 30604776

SN - 2041-1723

VL - 10

JO - Nature Communications

JF - Nature Communications

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M1 - 32

ER -