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David Sinton - One of the best experts on this subject based on the ideXlab platform.

  • nanomorphology enhanced gas evolution intensifies co2 reduction electrochemistry
    ACS Sustainable Chemistry & Engineering, 2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mas...

  • Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
    2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products

Thomas Burdyny - One of the best experts on this subject based on the ideXlab platform.

  • nanomorphology enhanced gas evolution intensifies co2 reduction electrochemistry
    ACS Sustainable Chemistry & Engineering, 2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mas...

  • Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
    2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products

Emily A Carter - One of the best experts on this subject based on the ideXlab platform.

  • water oxidation on pure and doped hematite 0001 Surfaces prediction of co and ni as effective dopants for electrocatalysis
    Journal of the American Chemical Society, 2012
    Co-Authors: Peilin Liao, John A Keith, Emily A Carter
    Abstract:

    In photoelectrochemical cells, sunlight may be converted into chemical energy by splitting water into hydrogen and oxygen molecules. Hematite (α-Fe2O3) is a promising photoanode material for the water oxidation component of this process. Numerous research groups have attempted to improve hematite’s photocatalytic efficiency despite a lack of foundational knowledge regarding its Surface Reaction Kinetics. To elucidate detailed Reaction mechanisms and energetics, we performed periodic density functional theory + U calculations for the water oxidation Reaction on the fully hydroxylated hematite (0001) Surface. We investigate two different concentrations of Surface reactive sites. Our best model involves calculating water oxidation mechanisms on a pure (1×1) hydroxylated hematite slab (corresponding to 1/3 ML of reactive sites) with an additional overlayer of water molecules to model solvation effects. This yields an overpotential of 0.77 V, a value only slightly above the 0.5–0.6 V experimental range. To exp...

  • water oxidation on pure and doped hematite 0001 Surfaces prediction of co and ni as effective dopants for electrocatalysis
    Journal of the American Chemical Society, 2012
    Co-Authors: Peilin Liao, John A Keith, Emily A Carter
    Abstract:

    In photoelectrochemical cells, sunlight may be converted into chemical energy by splitting water into hydrogen and oxygen molecules. Hematite (α-Fe(2)O(3)) is a promising photoanode material for the water oxidation component of this process. Numerous research groups have attempted to improve hematite's photocatalytic efficiency despite a lack of foundational knowledge regarding its Surface Reaction Kinetics. To elucidate detailed Reaction mechanisms and energetics, we performed periodic density functional theory + U calculations for the water oxidation Reaction on the fully hydroxylated hematite (0001) Surface. We investigate two different concentrations of Surface reactive sites. Our best model involves calculating water oxidation mechanisms on a pure (1×1) hydroxylated hematite slab (corresponding to 1/3 ML of reactive sites) with an additional overlayer of water molecules to model solvation effects. This yields an overpotential of 0.77 V, a value only slightly above the 0.5-0.6 V experimental range. To explore whether doped hematite can exhibit an even lower overpotential, we consider cation doping by substitution of Fe by Ti, Mn, Co, Ni, or Si and F anion doping by replacing O on the fully hydroxylated Surface. The Reaction energetics on pure or doped hematite Surfaces are described using a volcano plot. The relative stabilities of holes on the active O anions are identified as the underlying cause for trends in energetics predicted for different dopants. We show that moderately charged O anions give rise to smaller overpotentials. Co- or Ni-doped hematite Surfaces give the most thermodynamically favored Reaction pathway (lowest minimum overpotential) among all dopants considered. Very recent measurements (Electrochim. Acta 2012, 59, 121-127) reported improved reactivity with Ni doping, further validating our predictions.

Caothang Dinh - One of the best experts on this subject based on the ideXlab platform.

  • nanomorphology enhanced gas evolution intensifies co2 reduction electrochemistry
    ACS Sustainable Chemistry & Engineering, 2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mas...

  • Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
    2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products

Edward H Sargent - One of the best experts on this subject based on the ideXlab platform.

  • nanomorphology enhanced gas evolution intensifies co2 reduction electrochemistry
    ACS Sustainable Chemistry & Engineering, 2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mas...

  • Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
    2017
    Co-Authors: Thomas Burdyny, Percival J Graham, Yuanjie Pang, Caothang Dinh, Min Liu, Edward H Sargent, David Sinton
    Abstract:

    Nanostructured CO2 reduction catalysts now achieve near-unity Reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent Surface Reaction Kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm–2. We show here that – in addition to influencing Reaction rates and local reactant concentration – the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode’s Surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm–2 production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products