Origin of Hydrogen Incorporated into Ethylene during Electrochemical CO<sub>2</sub> Reduction in Membrane Electrode Assembly

Choi, Woong; Park, Seong-Ho; Jung, Wonsang; Won, Da Hye; Na, Jonggeol; Hwang, Yun Jeong

doi:10.1021/acsenergylett.1c02658

Cited by 45 publications

(34 citation statements)

References 32 publications

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“…Recently, it was reported that the protons C 2 H 4 are supplied by the aqueous anolyte; and that water in humidified CO 2 increases water activity and affects the GDE microenvironment, providing enhanced CO 2 RR kinetics. [ 42 ] We studied the effect of MOF layer (mass loading = 0.6 mg cm −2 ) by varying the MOF position (overlayer or underlayer) in GDE according to 165 nm sputtered Cu since the micro‐environment in MEA electrolyzer could be very different from the flow cell during CO 2 RR (Figure 3b).…”

Section: Resultsmentioning

confidence: 99%

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

et al. 2022

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tivity. To achieve economically compelling CO 2 RR, technoeconomic analysis (TEA) highlights the pressing need for industrially relevant productivity (>200 mA cm −2 ) and energy efficiency (>50%) for CO 2 to ethylene (C 2 H 4 ) conversion. [4,5] This emphasizes the importance of high selectivity, high energy efficiency, and high product yield. [4][5][6][7][8][9] There exists an urgent need to find electrocatalysts and reactors enabling to produce a specific chemical efficiently at a low cost.Understanding the CO 2 RR electrolyzer is crucial for this purpose. In an H-cell, CO 2 is bubbled into the electrolyte and the low CO 2 solubility limits the production rates of C 2 H 4 to several tens of mA cm −2 in CO 2 RR. [10] In the flow cell, where catholyte, anolyte, and CO 2 flow independently in separate chambers, CO 2 gas is supplied from the backside of a porous gas diffusion electrode (GDE), overcoming the mass transport limitation and achieving C 2 H 4 productivities of >100 mA cm −2 . [11] Membrane electrode assembly (MEA) electrolyzers are newly emerging systems, where cathode:membrane:anode are stacked together to minimize ohmic loss. [12,13] Electrocatalysts are deployed typically on hydrophobic and porous substrates to form GDEs. The design of GDEs is important to achieve efficient transport of CO 2 to the local reaction environment. [14,15] Three mass transport regions, which include the electrolyte phase reaction (bulk reaction), reaction High-rate conversion of carbon dioxide (CO2 ) to ethylene (C 2 H 4 ) in the CO 2 reduction reaction (CO 2 RR) requires fine control over the phase boundary of the gas diffusion electrode (GDE) to overcome the limit of CO 2 solubility in aqueous electrolytes. Here, a metal-organic framework (MOF)-functionalized GDE design is presented, based on a catalysts:MOFs:hydrophobic substrate materials layered architecture, that leads to high-rate and selective C 2 H 4 production in flow cells and membrane electrode assembly (MEA) electrolyzers. It is found that using electroanalysis and operando X-ray absorption spectroscopy (XAS), MOF-induced organic layers in GDEs augment the local CO 2 concentration near the active sites of the Cu catalysts. MOFs with different CO 2 adsorption abilities are used, and the stacking ordering of MOFs in the GDE is varied. While sputtering Cu on poly(tetrafluoroethylene) (PTFE) (Cu/PTFE) exhibits 43% C 2 H 4 Faradaic efficiency (FE) at a current density of 200 mA cm −2 in a flow cell, 49% C 2 H 4 FE at 1 A cm −2 is achieved on MOFaugmented GDEs in CO 2 RR. MOF-augmented GDEs are further evaluated in an MEA electrolyzer, achieving a C 2 H 4 partial current density of 220 mA cm −2 for CO 2 RR and 121 mA cm −2 for the carbon monoxide reduction reaction (CORR), representing 2.7-fold and 15-fold improvement in C 2 H 4 production rate, compared to those obtained on bare Cu/PTFE.

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Section: Resultsmentioning

confidence: 99%

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

et al. 2022

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“…Schematic of a membrane electrode assembly illustrating the mechanism of D-labeled experiments with humidified CO 2 supply. Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

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Gas Diffusion Electrodes for CO₂ and N₂ Reduction: A Virtual Issue

Kamat

Christopher

2022

ACS Energy Lett.

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“…[5][6][7] The state-of-the-art electrocatalysts for CO 2 RR are metallic. [8][9][10][11] Ag, Au, and Zn mainly convert CO 2 to carbon monoxide (CO), [12][13][14][15] while Sn and Bi are selective to formate (HCOO -) via a two-electron reduction process in CO 2 RR. [16][17][18] Cu stands out as the only known metal catalyst capable of generating high-order products such as C 1 -C 2 hydrocarbons (e.g., CH 4 and C 2 H 4 ) and C 2+ oxygenates (e.g., CH 3 CH 2 OH, CH 3 COOH, and C 3 H 7 OH,) beyond the 2ereduction route.…”

Section: Introductionmentioning

confidence: 99%

Revealing the activity and selectivity of ppm level copper in gas diffusion electrodes towards CO and CO₂ electroreduction

Lyu

Zhang

et al. 2023

EES. Catal.

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Origin of Hydrogen Incorporated into Ethylene during Electrochemical CO₂ Reduction in Membrane Electrode Assembly

Cited by 45 publications

References 32 publications

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

Gas Diffusion Electrodes for CO₂ and N₂ Reduction: A Virtual Issue

Revealing the activity and selectivity of ppm level copper in gas diffusion electrodes towards CO and CO₂ electroreduction

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Origin of Hydrogen Incorporated into Ethylene during Electrochemical CO2 Reduction in Membrane Electrode Assembly

Cited by 45 publications

References 32 publications

High‐Rate and Selective CO2 Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO2 Availability

High‐Rate and Selective CO2 Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO2 Availability

Gas Diffusion Electrodes for CO2 and N2 Reduction: A Virtual Issue

Revealing the activity and selectivity of ppm level copper in gas diffusion electrodes towards CO and CO2 electroreduction

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Origin of Hydrogen Incorporated into Ethylene during Electrochemical CO₂ Reduction in Membrane Electrode Assembly

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

High‐Rate and Selective CO₂ Electrolysis to Ethylene via Metal–Organic‐Framework‐Augmented CO₂ Availability

Gas Diffusion Electrodes for CO₂ and N₂ Reduction: A Virtual Issue

Revealing the activity and selectivity of ppm level copper in gas diffusion electrodes towards CO and CO₂ electroreduction