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F. Wisser - One of the best experts on this subject based on the ideXlab platform.

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2019
    Co-Authors: F. Wisser, J. Canivet
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frameworks made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heterogeneous catalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homogeneous and heterogenized catalysts follow the same linear correlation between the electronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts is demonstrated here for the photoReduction of Carbon Dioxide into formate with turnover frequencies up to 28 h−1, in the presence of a homogeneous photosensitizer.[2] We will also present completely heterogeneous photocatalysts to overcome the current limitation of photodegradation of the light harvesting moiety. In these systems both the photosensitizer and the catalyst are integrated into the same framework, either covalently to the backbone or by co-immobilized inside the pores. In the later case, the pores are used as nanoreactors, as the catalyst and photosensitizer are co-confined into the cavity’s nanospace and enable molecular catalysis in a heterogeneous manner.[3] This approach allows to develop a photocatalytic system that completely suppresses the hydrogen evolution typically observed as a side reaction. Finally, different photo-sensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. García, F. X. Llabrés i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, 2018, 11, 3315-3322.

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. Garcia, F. X. Llabres i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. García, F. X. Llabrés i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

D. Farrusseng - One of the best experts on this subject based on the ideXlab platform.

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. Garcia, F. X. Llabres i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. García, F. X. Llabrés i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

J. Canivet - One of the best experts on this subject based on the ideXlab platform.

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2019
    Co-Authors: F. Wisser, J. Canivet
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frameworks made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heterogeneous catalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homogeneous and heterogenized catalysts follow the same linear correlation between the electronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts is demonstrated here for the photoReduction of Carbon Dioxide into formate with turnover frequencies up to 28 h−1, in the presence of a homogeneous photosensitizer.[2] We will also present completely heterogeneous photocatalysts to overcome the current limitation of photodegradation of the light harvesting moiety. In these systems both the photosensitizer and the catalyst are integrated into the same framework, either covalently to the backbone or by co-immobilized inside the pores. In the later case, the pores are used as nanoreactors, as the catalyst and photosensitizer are co-confined into the cavity’s nanospace and enable molecular catalysis in a heterogeneous manner.[3] This approach allows to develop a photocatalytic system that completely suppresses the hydrogen evolution typically observed as a side reaction. Finally, different photo-sensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. García, F. X. Llabrés i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, 2018, 11, 3315-3322.

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. Garcia, F. X. Llabres i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

  • Tailor Made Heterogeneous Photocatalysts for Carbon Dioxide Reduction based on Microporous Macroligands
    2018
    Co-Authors: F. Wisser, J. Canivet, C. Mellot-draznieks, D. Farrusseng
    Abstract:

    Heterogeneous catalysis allows to circumvent the problem of separation of the catalyst from the products and to simplify its recyclability. The integration of the catalytically active centers into a solid support without loss of performance compared to the homogeneous analog is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. In particular, porous frame-works made by the repetition of a coordinating motif, like the bipyridine motif are of a high interest as bipyridines are widely used as chelating ligand for molecular catalysts.[1] Amongst the catalytic applications, photochemical Carbon Dioxide Reduction is of tremendous importance as routes to renewable energy sources. Here we present a series of heteroge-neous photocatalysts based on metal-organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes.[2] We show that both homo-geneous and heterogenized catalysts follow the same linear correlation between the elec-tronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. This is demonstrated here for the Rh-catalyzed photoReduction of Carbon Dioxide into formate with turnover frequencies (TOF) up to 28 h−1, the highest TOFs reported so far for heterogeneous photocatalytic formate production.[2] We will also present completely heterogeneous photocatalysts to overcome the current limi-tation of photodegradation of the light harvesting moiety. In these systems both the photo-sensitizer and the catalyst are integrated into the same framework,[3] thus increasing the long-term stability of the catalyst. In addition, different photosensitizers will be evaluated in terms of their light absorption properties and the resulting catalytic activities. References: [1] a) A. Corma, H. García, F. X. Llabrés i Xamena Chem. Rev. 2010, 110, 4606-4655; b) C. Kaes, A. Katz, M. W. Hosseini Chem. Rev. 2000, 100, 3553-3590. [2] F. M. Wisser, P. Berruyer, L. Cardenas, Y. Mohr, E. A. Quadrelli, A. Lesage, D. Farrusseng, J. Canivet ACS Catal. 2018, 8, 1653-1661. [3] X. Wang, F. M. Wisser, J. Canivet, M. Fontecave, C. Mellot-Draznieks, ChemSusChem, DOI: 10.1002/cssc.201801066

Erin B. Creel - One of the best experts on this subject based on the ideXlab platform.

  • Shining a Light on Plasmonic Photoelectrochemical Carbon Dioxide Reduction
    2019
    Co-Authors: Erin B. Creel
    Abstract:

    Author(s): Creel, Erin | Advisor(s): McCloskey, Bryan D.; Saykally, Richard J. | Abstract: Electrochemical Carbon Dioxide (CO2) Reduction is one possible component of the effort to mitigate atmospheric CO2 concentration and develop a reliable renewable fuel source. However, CO2 Reduction suffers from the high overpotentials needed to overcome sluggish kinetics, low selectivity for desired products, and unfavorable competition with water Reduction (hydrogen evolution reaction (HER)). Challenges limiting energy efficiency and selective product formation must be addressed to make CO2 Reduction a viable energy storage solution.Plasmonic catalysis may bypass the shortcomings in traditional "dark" catalysis for multi-electron Reductions because of its ability to couple light energy into surface chemistry. Surface plasmon resonance (SPR) in nanostructured metals has been shown to increasereaction rates or alter selectivity in a variety of reactions, including gas-phase CO2 Reduction. However, the effect of SPR on the coulombic efficiency and selectivity of electrochemical CO2 Reduction product(s) has not been extensively explored despite the promising improvements in selectivity seen in purely plasmonic photocatalytic (without voltage bias) CO2 Reduction.In this dissertation, I explore the effect of SPR on aqueous electrochemical CO2 Reduction. Incorporating illumination into any electrochemical system poses electrochemical cell geometry and temperature regulation challenges. In order to promote experiment reproducibility and enable direct comparison of photoelectrochemistry (PEC) studies across various laboratories, I outline a few best practices. The temperature of the electrochemical cell affects not only the reaction rate but also reaction selectivity in reactions with multiple products, and illumination may increase the temperature of the electrochemical cell components dramatically. Thus, the temperature of the electrochemical cell must either be regulated or reported. The materials, electrolyte, and path length from the surface to the photoelectrode vary between PEC cells. Each of these factors influences the light attenuation, necessitating that the light flux be measured at the surface of the photoelectrode so that conditions can be repeated in different cells. Additionally, a careful comparison of the photoelectrode before and after PEC is required for adequate stability characterization because both photoexcitation and applied voltage can affect the composition and morphology of materials.Incorporating illumination into an electrochemical Carbon Dioxide Reduction (CO2R) system poses additional challenges due to the requirements of supplying a gas (CO2) to the reaction vessel and detecting trace amounts of both gaseous and soluble products. Parallel electrodes reduce the potential gradients across their surfaces, front illumination of the photoelectrode allows more photoexcited charge carriers to reach the electrtrochemically active surface, small catholyte and anolyte volumes allows decreased electrolysis times necessary to detect trace soluble products, continuous CO2 sparging maintains CO2 saturation of the electrolyte and carries evolved gaseous products to an in-line gas chromatograph (GC), a temperature control system maintains a constant catholyte temperature so that the effects of temperature and illumination can be decoupled, a membrane separating the catholyte and anolyte to prevent soluble CO2R products from being oxidized at the anode. The CO2R product distribution and current density of silver foil electrodes is indistinguishable between this PEC cell and a conventional compression electrochemical CO2R cell.The newly developed front-illumination electrochemical CO2R cell allows for the full characterization of the electrochemical CO2R performance of an illuminated and unilluminated electron-beam-deposited thin film polycrystalline silver electrode. The as-deposited electrode increases in absorption, decreases in elctrochemical surface area (ECSA), and broadens in particle size distribution over 45 min of elctrochemical CO2R, but these properties are then stable for hours of CO2R. The electrode exhibits a SPR absorption peak at 351 nm and was illuminated with a 365 nm light-emitting diode (LED). At small applied overpotentials (−0.8 to −0.6 Volts versus the reversible hydrogen electrode (VRHE)), illuminating the thin film Ag electrode increases the production rate of Carbon monoxide (CO) and decreases the hydrogen (H2) production rate. This may be the first time that one reaction is enhanced while another is simultaneously suppressed by a plasmonic effect. Illuminating the Ag electrode decreases the overpotential required to generate CO selectively. The plasmonic effect suppresses the total reaction rate when the electrolyte is saturated with inert Ar rather than CO2. Thismay be the first electrochemical reaction that is suppressed through a photoeffect. The CO2 Reduction product that is promoted with plasmon excitation depends on the applied voltage. At larger cathodic potentials (−1.1 to −0.8 VRHE), methanol and formate productionrates are increased while CO and H2 production rates remain the same. This is the first demonstration of potential-dependent selectivity in any plasmon-enhanced reaction. The photoeffect is proportional to absorption and scales linearly with light intensity, two strongindicators that the activity is photonic rather than thermal in nature.The nanofeatures on the silver thin film electrode are not intentionally controlled, but it still exhibited remarkable photoactivity and selectivity for CO2R. Perhaps if the nanofeatures were rationally designed with specific sizes, shapes, and compositions, the photoactivity could be increased or the selectivity altered. Solution-based, electrochemical, and lithographic approaches to nanosynthesis are explored for creating nanopatterned electrodes. Though nanofeature-modified electrode stability has limited the investigation of these well-defined photoelectrodes, there may be additional strategies that have not yet been explored forstabilization.There is still more work needed to understand the mechanism for plasmon-enhanced electrochemical CO2R and increase the energy efficiency of plasmonic CO2R, but this work clearly demonstrates the unique selectivity achievable through the combination of plasmonics and electrochemistry. Plasmonics may also be a valuable tool in other multi-electron, multiproduct electrochemical reactions such as nitrogen (N2) Reduction.

  • Directing Selectivity of Electrochemical Carbon Dioxide Reduction Using Plasmonics
    ACS Energy Letters, 2019
    Co-Authors: Erin B. Creel, Elizabeth R. Corson, Johanna Eichhorn, Robert Kostecki, Jeffrey J. Urban, Bryan D. Mccloskey
    Abstract:

    Catalysts for electrochemical Carbon Dioxide Reduction in aqueous electrolytes suffer from high energy input requirements, competition with hydrogen evolution from water Reduction, and low product selectivity. Theory suggests that plasmonic catalysts can be tuned to selectively lower the energy barrier for a specific reaction in a set of competitive reactions, but there has been little experimental evidence demonstrating plasmon-driven selectivity in complicated multielectron electrochemical processes. Here, the photoactivity at a plasmonically active silver thin film electrode at small cathodic potentials selectively generates Carbon monoxide while simultaneously suppressing hydrogen production. At larger cathodic potentials, the photoactivity promotes production of methanol and formate. Methanol production is observed only under illumination, not in dark conditions. The preference of the plasmonic activity for Carbon Dioxide Reduction over hydrogen evolution and the ability to tune plasmonic activity wi...

Vladimir V Rybkin - One of the best experts on this subject based on the ideXlab platform.

  • Mechanism of Aqueous Carbon Dioxide Reduction by the Solvated Electron.
    The Journal of Physical Chemistry B, 2020
    Co-Authors: Vladimir V Rybkin
    Abstract:

    Aqueous solvated electron (eaq-), a key species in radiation and plasma chemistry, can efficiently reduce CO2 in a potential green chemistry application. Here, the mechanism of this reaction is unravelled by condensed-phase molecular dynamics based on the correlated wave function and an accurate density functional theory (DFT) approximation. Here, we design and apply the holistic protocol for solvated electron's reactions encompassing all relevant reaction stages starting from diffusion. The Carbon Dioxide Reduction proceeds via a cavity intermediate, which is separated from the product (CO2-) by an energy barrier due to the bending of CO2 and the corresponding solvent reorganization energy. The formation of the intermediate is caused by solvated electron's diffusion, whereas the intermediate transformation to CO2- is triggered by hydrogen bond breaking in the second solvation shell of the solvated electron. This picture of an activation-controlled eaq- reaction is very different from both rapid barrierless electron transfer and proton-coupled electron transfer, where key transformations are caused by proton migration.

  • Mechanism of Aqueous Carbon Dioxide Reduction by the Solvated Electron
    2020
    Co-Authors: Vladimir V Rybkin
    Abstract:

    Aqueous solvated electron, e<sub>aq</sub>, a key species in radiation and plasma chemistry, can effciently reduce CO<sub>2</sub> in a potential green chemistry application. Here, the mechanism of this reaction is unravelled by condensed-phase Born-Oppenheimer molecular dynamics based on the correlated wave function and accurate DFT approximation. We introduce and apply the holistic protocol for solvated electron's reactions encompassing all relevant reaction stages starting from diffusion. The Carbon Dioxide Reduction proceeds via a cavity intermediate, which is separated from the product, CO2<sup>-</sup>, by an energy barrier due to the bending of CO<sub>2</sub> and the corresponding solvent reorganization energy. The formation of the intermediate is caused by solvated electron's diffusion, whereas the intermediate transformation to CO<sub>2</sub><sup>-</sup> is triggered by solvent fluctuations. This picture of activation-controlled e<sub>aq</sub> reaction is very different from both rapid barrierless electron transfer, and proton-coupled electron transfer, where key transformations are caused by proton migration.