Mass transfer effects in CO<sub>2</sub> reduction on Cu nanowire electrocatalysts

Raciti, David; Mao, Mark; Park, Jun Ha; Wang, Chao

doi:10.1039/c8cy00372f

Cited by 60 publications

(59 citation statements)

References 35 publications

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“…At the same time, the reaction interface that governs the solid–liquid contact and mass transfer is also of vital importance to the photocatalytic CO 2 conversion process. Previous studies found that the availability of excess protons (H + ) and low concentration of CO 2 at the reaction interface lead to unsatisfactory activity and selectivity of the photocatalytic CO 2 reduction system . In a conventional liquid–solid diphase system for CO 2 photoreduction, the availability of CO 2 at the reaction interface is dependent on its mass transfer through the water phase .…”

Section: Figurementioning

confidence: 99%

“…Previous studies found that the availability of excess protons (H + ) and low concentrationo fC O 2 at the reaction interfacel ead to unsatisfactory activity ands electivity of the photocatalytic CO 2 reduction system. [8] In ac onventional liquid-solid diphase system for CO 2 photoreduction, the availability of CO 2 at the reactioni nterface is dependent on its mass transfer through the water phase. [9] The low concentration and slow diffusion rate of CO 2 molecules in water thereby strongly hindert he surface catalytic process of CO 2 photoreduction.…”

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confidence: 99%

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Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂

et al. 2020

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The activity and selectivity of simple photocatalysts for CO2 reduction remain limited by the insufficient photophysics of the catalysts, as well as the low solubility and slow mass transport of gas molecules in/through aqueous solution. In this study, these limitations are overcome by constructing a triphasic photocatalytic system, in which polymeric carbon nitride (CN) is immobilized onto a hydrophobic substrate, and the photocatalytic reduction reaction occurs at a gas–liquid–solid (CO2–water–catalyst) triple interface. CN anchored onto the surface of a hydrophobic substrate exhibits an approximately 7.2‐fold enhancement in total CO2 conversion, with a rate of 415.50 μmol m−2 h−1 under simulated solar light irradiation. This value corresponds to an overall photosynthetic efficiency for full water–CO2 conversion of 0.33 %, which is very close to biological systems. A remarkable enhancement of direct C2 hydrocarbon production and a high CO2 conversion selectivity of 97.7 % are observed. Going from water oxidation to phosphate oxidation, the quantum yield is increased to 1.28 %.

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Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂

et al. 2020

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“…45 On the other hand, products formed via a pH independent pathway, such as ethylene and CO, will be affected mostly by CO 2 gradients and have a higher selectivity inside the pores due to the suppression of hydrogen evolution unless the catalyst layer becomes too thick. 42,46 From this understanding, the highest product selectivity will be obtained on an electrocatalyst with an optimal catalyst layer thickness that balances pH dependent and independent pathways. Specifically, a layer of sufficient thickness is needed to create an alkaline environment inside the pores, yet sufficiently thin to allow CO 2 diffuse through the entire catalyst layer.…”

Section: Nanostructured Electrodesmentioning

confidence: 99%

“…Specifically, a layer of sufficient thickness is needed to create an alkaline environment inside the pores, yet sufficiently thin to allow CO 2 diffuse through the entire catalyst layer. 44,46 Furthermore, stable intermediates such as CO, ethylene, and formaldehyde need to be transported away from the porous and nanostructured catalyst layer to be observed as a final product. Re-adsorption of these intermediates or reactions with adsorbed molecules via an Eley-Rideal type of mechanism is proposed to result in the production of more reduced compounds such as ethane and propanol, 47-49 depending on the dimensions and structure of the pores.…”

Section: Nanostructured Electrodesmentioning

confidence: 99%

Electrochemical CO2 Reduction on Nanostructured Metal Electrodes: Fact or Defect?

Kaş¹,

Yang²,

Bohra³

et al. 2019

Preprint

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a Electrochemical CO2 reduction has received an increased amount of interest in the last decade as a promising avenue for storing renewable electricity in chemical bonds. Despite considerable progress on catalyst performance using nanostructured electrodes, the sensitivity of the reaction to process conditions has led to debate on the origin of the activity and high selectivity. Additionally, this raises questions on the transferability of the performance and knowledge to other electrochemical systems. At its core, the discrepancy is primarily a result of the highly porous nature of nanostructured electrodes, which are vulnerable to both mass transport effects and structural changes during the electrolysis. Both effects are not straightforward to identify and difficult to decouple. Despite the susceptibility of nanostructured electrodes to mass transfer limitations, we highlight that nanostructured silver electrodes exhibit considerably higher activity when normalized to the electrochemically active surface in contrast to gold and copper electrodes. Alongside, we provide a discussion on how active surface area and thickness of the catalytic layer itself can influence the selectivity, stability, activity and mass transfer inside and outside of the three dimensional catalyst layer. Key parameters and potential solutions are highlighted to decouple mass transfer effects from the measured activity in electrochemical cells utilizing CO2 saturated aqueous solutions.

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“…15,17,18 We simulated the pH at the interfaces of the catalysts using the effective diffusivities of [CO2]aq, HCO3 -, CO3 2and OHand a previously reported mass transport model. [43][44][45] In the model, the effective diffusivity in porous media is given as 9 = , = => ? , where is the correlation factor, is the bulk diffusivity, is the porosity fraction, which is the ratio of the void space to total volume, is the constriction factor, which accounts for the difference in cross-sectional area normal to diffusion and is the tortuosity, which is the actual distance a molecule travels divided by the shortest distance between two points.…”

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confidence: 99%

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

Kwok¹,

Wang²,

Cao³

et al. 2019

Preprint

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The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Here, using a pre-strained polymer, we uniaxially compress a thin gold film to form a nano-folded catalyst. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of pre-strain in the polymer. We characterize the nano-folded catalysts using x-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. Electroreduction of carbon dioxide with these nano-folded catalysts reveals an enhancement of Faradaic efficiency for carbon monoxide formation by a factor of about four. This result suggests that electrolyte mass transport limitations and an increase of the local pH in the tight folds of the catalyst outweigh the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic selectivity.Electroreduction of carbon dioxide (CO2) to valuable carbon-rich products is a potential solution to end the anthropogenic carbon cycle. 1,2 However, slow kinetics and reduced control over product yield and selectivity have hindered widespread commercial viability. 3,4 Nanostructured catalysts offer the potential to address these limitations. 5 Indeed, a variety of nanoparticles, 6-9 thin films, 10-14 and nanoporous materials 15-18 have been explored, but there are still challenges with scalability, reproducibility, extreme reaction conditions, and cost. 6,10,12,15 Mechanical wrinkling of metallic thin films using pre-strained polystyrene (PS) substrates offers a reproducible strategy to create nanostructured interfaces. This approach is compatible with nanoparticles, 19 nanoporous, 20 thin films, 21,22 and twodimensional (2D) materials (e.g. graphene and MoS2), 23-28 and the morphology can be controlled using lithography. 24,25,29,30 Previous studies with wrinkled catalysts show improvement in different electrochemical reactions including hydrogen evolution reaction (HER), 25,27,28,30 glucose sensing, 31 and DNA detection. 32 For example, wrinkled platinum (Pt) arrays electrodes improved the performance of HER from ~70 mA/cm 2 to ~ 120 mA/cm 2 at 0.1 V as compared to conventional Pt on carbon. This improvement was attributed to weak adhesion of hydrogen (H2) gas bubbles, resulting in a lower overpotential.Here, for the first time, we present evidence that a nano-folded gold (Au) catalyst can improve the selectivity of CO2 reduction. We utilized a pre-strained PS substrate to uniaxially compress and create a novel Au catalyst with a combination of loose (>200

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Mass transfer effects in CO₂ reduction on Cu nanowire electrocatalysts

Abstract: Mass transfer effects play an important role in CO2 electroreduction, giving rise to diffusion-limited activity and selectivity on Cu nanowire electrocatalysts.

Cited by 60 publications

References 35 publications

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂

Electrochemical CO2 Reduction on Nanostructured Metal Electrodes: Fact or Defect?

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

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Mass transfer effects in CO2 reduction on Cu nanowire electrocatalysts

Abstract: Mass transfer effects play an important role in CO2 electroreduction, giving rise to diffusion-limited activity and selectivity on Cu nanowire electrocatalysts.

Cited by 60 publications

References 35 publications

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO2Reduction to C1and C2Fuels and O2

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO2Reduction to C1and C2Fuels and O2

Electrochemical CO2 Reduction on Nanostructured Metal Electrodes: Fact or Defect?

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

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Product

Resources

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Mass transfer effects in CO₂ reduction on Cu nanowire electrocatalysts

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂

Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂Reduction to C₁and C₂Fuels and O₂