Enhanced selectivity of carbonaceous products from electrochemical reduction of CO2 in aqueous media

Xiang, Hang; Rasul, Shahid; Scott, Keith; Portolés, José F.; Cumpson, Peter J.; Yu, Eileen Hao

doi:10.1016/j.jcou.2019.02.007

Cited by 50 publications

(82 citation statements)

References 49 publications

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“…However, the CO 2 R selectivity was still unsatisfying. Thus, we further optimized the catalyst layer with respect to the local pH, as it has been shown to be crucial for efficient CO 2 R. [ 56,57 ] Furthermore, ionomer modifications have been shown to enhance the combined hydrophobic and hydrophilic properties necessary for efficient CO 2 R. [ 58,59 ] A straightforward method to enable such a local pH change, while providing high surface wettability, is by modifying the catalyst layer with an additional ionomeric coating. Ultimately, a hydrophilicity gradient is implemented by adding a hydrophilic ionomer coating to the bulk hydrophobic catalyst layer.…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

Puring

Siegmund

Timm

et al. 2020

Advanced Sustainable Systems

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The electrochemical conversion of CO2 into commodity chemicals or fuels is an attractive reaction for sustainable CO2 utilization. In this context, the application of gas diffusion electrodes is promising due to efficient CO2 mass transport. Herein, a scalable and reproducible method is presented for polytetrafluoroethylene (PTFE)‐bound copper gas diffusion electrodes (GDEs) via the dry‐pressing method and compositional parameters are emphasized to alter such electrodes. The assembly of the catalytic layer plays a critical role in the electrode performance, as elevated bulk hydrophobicity coupled with good surface wettability is observed to offer highest performance in 0.5 m KHCO3. With optimized electrodes, formate, CO, and H2 are obtained at a current density of 25 mA cm−2 as main products in 1 m KOH in faradaic efficiencies (FEs) of 27%, 30%, and 36%. At 200 mA cm−2, an altered product composition with ethylene (33% FE) and ethanol (9% FE) along with H2 (33% FE) is observed. In addition, n‐propanol is observed with 7% faradaic efficiency. The results indicate that the composition of the GDE has a severe influence on the electrode performance and setting proper hydrophobicity gradients within the electrode is key toward developing a successful electrochemical CO2 reduction.

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Section: Resultsmentioning

confidence: 99%

“…We attribute this phenomenon to the high concentration of hydroxide ions, which was shown to facilitate C–C coupling in CO 2 R with same Cu‐based GDEs. [ 17,57,65 ] Under such high pH conditions, the CO hydrogenation on Cu catalysts is predicted to be kinetically hindered paving the way for C‐C coupling to occur. [ 39,66 ]…”

Section: Resultsmentioning

confidence: 99%

Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

Puring

Siegmund

Timm

et al. 2020

Advanced Sustainable Systems

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“…The fabrication of an efficient ow cell with a designed gas diffusion electrode (GDE) could dramatically promote the activity and stability of CO 2 electrocatalysts. More and more attention has been paid to this area over the past two years, 103,110,185,208,240 and future efforts could be also made towards this aspect. a The potential applied for EC CO 2 reduction versus RHE is calculated according to the equation E (vs. RHE) ¼ E 0 (vs. Ag/AgCl) + E (vs. Ag/AgCl) + 0.0591pH À h(IR drop ) in aqueous solution.…”

Section: Discussionmentioning

confidence: 99%

“…In aqueous systems, alkaline conditions could promote C-C coupling during CO 2 reduction. 207,208 For the ultimate goal of CO 2 recycling, neutral aqueous solution is the best choice and various concentrations and cations could be applied to tune the activity.…”

Section: Non-aqueous Solventsmentioning

confidence: 99%

An overview of Cu-based heterogeneous electrocatalysts for CO₂reduction

et al. 2020

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“…A range of approaches, including electrochemical methods, have been developed to reduce CO 2 to valuable chemicals 3 . Over the past few decades, metal catalysts such as copper have been commonly used for electrochemical reduction of CO 2 and have received lots of attention in this area [4][5][6][7] . Microbial electrosynthesis (MES) is a bio-electrochemical technique that has offered the sustainable conversion of CO 2 to valuable organic chemicals at the cathode of bio-electrochemical systems (BES), using microorganisms as biocatalysts [8][9][10] .…”

Section: Introductionmentioning

confidence: 99%

Parameters influencing the development of highly conductive and efficient biofilm during microbial electrosynthesis: the importance of applied potential and inorganic carbon source

Izadi

Fontmorin

Godain

et al. 2020

npj Biofilms Microbiomes

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Cathode-driven applications of bio-electrochemical systems (BESs) have the potential to transform CO2 into value-added chemicals using microorganisms. However, their commercialisation is limited as biocathodes in BESs are characterised by slow start-up and low efficiency. Understanding biosynthesis pathways, electron transfer mechanisms and the effect of operational variables on microbial electrosynthesis (MES) is of fundamental importance to advance these applications of a system that has the capacity to convert CO2 to organics and is potentially sustainable. In this work, we demonstrate that cathodic potential and inorganic carbon source are keys for the development of a dense and conductive biofilm that ensures high efficiency in the overall system. Applying the cathodic potential of −1.0 V vs. Ag/AgCl and providing only gaseous CO2 in our system, a dense biofilm dominated by Acetobacterium (ca. 50% of biofilm) was formed. The superior biofilm density was significantly correlated with a higher production yield of organic chemicals, particularly acetate. Together, a significant decrease in the H2 evolution overpotential (by 200 mV) and abundant nifH genes within the biofilm were observed. This can only be mechanistically explained if intracellular hydrogen production with direct electron uptake from the cathode via nitrogenase within bacterial cells is occurring in addition to the commonly observed extracellular H2 production. Indeed, the enzymatic activity within the biofilm accelerated the electron transfer. This was evidenced by an increase in the coulombic efficiency (ca. 69%) and a 10-fold decrease in the charge transfer resistance. This is the first report of such a significant decrease in the charge resistance via the development of a highly conductive biofilm during MES. The results highlight the fundamental importance of maintaining a highly active autotrophic Acetobacterium population through feeding CO2 in gaseous form, which its dominance in the biocathode leads to a higher efficiency of the system.

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Enhanced selectivity of carbonaceous products from electrochemical reduction of CO2 in aqueous media

Cited by 50 publications

References 49 publications

Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

An overview of Cu-based heterogeneous electrocatalysts for CO₂reduction

Parameters influencing the development of highly conductive and efficient biofilm during microbial electrosynthesis: the importance of applied potential and inorganic carbon source

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Enhanced selectivity of carbonaceous products from electrochemical reduction of CO2 in aqueous media

Cited by 50 publications

References 49 publications

Electrochemical CO2 Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

Electrochemical CO2 Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

An overview of Cu-based heterogeneous electrocatalysts for CO2reduction

Parameters influencing the development of highly conductive and efficient biofilm during microbial electrosynthesis: the importance of applied potential and inorganic carbon source

Contact Info

Product

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Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

Electrochemical CO₂ Reduction: Tailoring Catalyst Layers in Gas Diffusion Electrodes

An overview of Cu-based heterogeneous electrocatalysts for CO₂reduction