19 results on '"Alexander Bagger"'
Search Results
2. Steering carbon dioxide reduction toward C–C coupling using copper electrodes modified with porous molecular films
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Siqi Zhao, Oliver Christensen, Zhaozong Sun, Hongqing Liang, Alexander Bagger, Kristian Torbensen, Pegah Nazari, Jeppe Vang Lauritsen, Steen Uttrup Pedersen, Jan Rossmeisl, and Kim Daasbjerg
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Multidisciplinary ,catalysis ,partial pressure ,carbon dioxide ,General Physics and Astronomy ,General Chemistry ,electrode ,carbon monoxide ,General Biochemistry, Genetics and Molecular Biology ,copper ,immobilization ,ethylene ,molecular analysis ,catalyst ,electrochemical method - Abstract
Copper offers unique capability as catalyst for multicarbon compounds production in the electrochemical carbon dioxide reduction reaction. In lieu of conventional catalysis alloying with other elements, copper can be modified with organic molecules to regulate product distribution. Here, we systematically study to which extent the carbon dioxide reduction is affected by film thickness and porosity. On a polycrystalline copper electrode, immobilization of porous bipyridine-based films of varying thicknesses is shown to result in almost an order of magnitude enhancement of the intrinsic current density pertaining to ethylene formation while multicarbon products selectivity increases from 9.7 to 61.9%. In contrast, the total current density remains mostly unaffected by the modification once it is normalized with respect to the electrochemical active surface area. Supported by a microkinetic model, we propose that porous and thick films increase both local carbon monoxide partial pressure and the carbon monoxide surface coverage by retaining in situ generated carbon monoxide. This reroutes the reaction pathway toward multicarbon products by enhancing carbon–carbon coupling. Our study highlights the significance of customizing the molecular film structure to improve the selectivity of copper catalysts for carbon dioxide reduction reaction.
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- 2023
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3. Near ambient N2 fixation on solid electrodes versus enzymes and homogeneous catalysts
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Olivia Westhead, Jesús Barrio, Alexander Bagger, James W. Murray, Jan Rossmeisl, Maria-Magdalena Titirici, Rhodri Jervis, Andrea Fantuzzi, Andrew Ashley, and Ifan E. L. Stephens
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General Chemical Engineering ,General Chemistry - Abstract
The Mo/Fe nitrogenase enzyme is unique in its ability to efficiently reduce dinitrogen to ammonia at atmospheric pressures and room temperature. Should an artificial electrolytic device achieve the same feat, it would revolutionise fertilizers and even provide an energy dense, truly carbon-free fuel. This Review provides a coherent comparison of recent progress made in dinitrogen fixation on (i) solid electrodes, (ii) homogeneous catalysts and (iii) nitrogenases. Specific emphasis is placed on systems for which there is unequivocal evidence that dinitrogen reduction has taken place. By establishing the cross-cutting themes and synergies between these systems, we identify viable avenues for future research.
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- 2022
4. Can the CO2Reduction Reaction Be Improved on Cu:Selectivity and Intrinsic Activity of Functionalized Cu Surfaces
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Oliver Christensen, Siqi Zhao, Zhaozong Sun, Alexander Bagger, Jeppe Vang Lauritsen, Steen Uttrup Pedersen, Kim Daasbjerg, and Jan Rossmeisl
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electrochemistry ,COreduction ,molecular modifiers ,diffusion ,surface roughness ,intrinsic activity ,General Chemistry ,benchmarking ,Catalysis ,copper catalyst - Abstract
Cu is currently the most effective monometallic catalyst for producing valuable multicarbon-based (C2+) products, such as ethylene and ethanol, from the CO2reduction reaction (CO2RR). One approach to optimize the activity and selectivity of the metal Cu catalyst is to functionalize the Cu electrode with a molecular modifier. We investigate from a data standpoint whether any reported functionalized Cu catalyst improves the intrinsic activity and/or multicarbon product selectivity compared to the performance of bare Cu foil and the best single crystal Cu facets. Our analysis shows that the reported increases in activity are due to increased surface roughness and disappear once normalized with respect to electrochemical surface area. The intrinsic activity generally falls below that of the bare Cu foil reference, both for total and product-specific current, which we attribute to nonselective blocking of active sites by the modifier on the surface. Instead, an analysis of various polymer diffusion coefficients indicates that the modifier allows for easier diffusion of CO2compared to H2O to the surface, leading to greater selectivity for CO2RR and C2+products. As such, our analysis finds no catalyst for CO2RR that intrinsically outperforms bare Cu.
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- 2022
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5. Electrochemical Synthesis of Urea: Co-reduction of Nitric Oxide and Carbon Monoxide
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Hao Wan, Xingli Wang, Lei Tan, Michael Filippi, Peter Strasser, Jan Rossmeisl, and Alexander Bagger
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General Chemistry ,Catalysis - Abstract
Electrocatalytic conversion is a promising technology for storing renewable electricity in the chemical form. Substantial efforts have been made on the multi-carbon feedstock production,while producing nitrogen-containing chemicals like urea via C-N coupling little is known. Here, we elucidate the possible urea production on metals through co-reduction of nitric oxide (NO) and carbon oxide (CO). Based on adsorption energies calculated by DFT, we find that Cu is able to bind both *NO and *CO while not binding *H. During NO + CO co-reduction, we identify two kinetically and thermodynamically possible C-N couplings via *CO + *N and *CONH + *N, and further hydrogenation leads to urea formation. A 2-D activity heatmap has been constructed for describing nitrogen conversion to urea. This work provides a clear example of using computational simulations to predict selective and active materials for sustainable urea production.
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- 2022
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6. Structure of the (Bi)carbonate Adlayer on Cu(100) Electrodes
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Reihaneh Amirbeigiarab, Alexander Bagger, Jing Tian, Jan Rossmeisl, and Olaf M. Magnussen
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Electrochemical Interfaces ,ADSORPTION ,Scanning Tunnelling Microscopy ,SCANNING-TUNNELING-MICROSCOPY ,General Chemistry ,General Medicine ,Catalysis ,Carbon Dioxide Reduction ,CU(111) ,IN-SITU STM ,Carbonate Adsorption ,INITIAL-STAGES ,PHOSPHATE ,RECONSTRUCTION ,Density Functional Theory ,CU ,SULFATE ,ELECTROCHEMICAL CO2 REDUCTION - Abstract
(Bi)carbonate adsorption on Cu(100) in 0.1 M KHCO3 has been studied by in situ scanning tunneling microscopy. Coexistence of different ordered adlayer phases with ( 2 ${\sqrt{2}}$ x6 2 ${\sqrt{2}}$ )R45 degrees and (4x4) unit cells was observed in the double layer potential regime. The adlayer is rather dynamic and undergoes a reversible order-disorder phase transition at 0 V vs. the reversible hydrogen electrode. Density functional calculations indicate that the adlayer consists of coadsorbed carbonate and water molecules and is strongly stabilized by liquid water in the adjacent electrolyte.
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- 2022
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7. Exploring the Composition Space of High-Entropy Alloy Nanoparticles for the Electrocatalytic H2/CO Oxidation with Bayesian Optimization
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Vladislav A. Mints, Jack K. Pedersen, Alexander Bagger, Jonathan Quinson, Andy S. Anker, Kirsten M. Ø. Jensen, Jan Rossmeisl, and Matthias Arenz
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high-entropy alloy nanoparticles ,machine learning ,H/CO oxidation reaction ,electrocatalysis ,General Chemistry ,Catalysis - Abstract
High-entropy alloy (HEA) electrocatalysts offer a vast composition space that awaits exploration to identify interesting materials for energy conversion reactions. While attempts have been made to explore the composition space of HEA thin-film libraries and compare experimental and computational studies, no corresponding approaches exist for HEA nanoparticles. So far, catalytic investigations on HEA nanoparticles are limited to small sets of individual catalysts. Here, we report the experimental exploration of the composition space of carbon-supported Pt−Ru−Pd−Rh− Au nanoparticles for the H2/CO oxidation reaction by constructing a dataset using Bayesian optimization as guidance. Applying a surfactant-free synthesis platform, a dataset of 68 samples was investigated. By constructing machine learning models, the relationship between the concentrations of the constituent elements and the catalytic activity was analyzed and compared to density functional theory calculations. The machine learning models confirm findings from previous studies concerning the role of Ru in the H2/CO oxidation reaction. This has been achieved starting from a random set of compositions and without any prior assumptions for the reaction mechanism nor any in-depth design of the active site. In addition, by comparing the trends of the computational and experimental studies, it is seen that the “onset potentials” across the compositions can be correlated with the adsorption energy of *OH. The best correlation between the computational and experimental data is obtained when considering 5% of the most strongly *OH adsorbing sites.
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- 2022
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8. pH and Anion Effects on Cu–Phosphate Interfaces for CO Electroreduction
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Alexander Bagger, Amanda Schramm Petersen, María Escudero-Escribano, Paula Sebastián-Pascual, and Jan Rossmeisl
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010405 organic chemistry ,Inorganic chemistry ,General Chemistry ,Renewable fuels ,010402 general chemistry ,Phosphate ,Electrocatalyst ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Ion ,chemistry.chemical_compound ,chemistry ,Electrode ,Cyclic voltammetry - Abstract
Cu electrodes are promising materials to catalyze the conversion of CO2 and CO into renewable fuels and valuable chemicals. However, a detailed description of the properties of the Cu–electrolyte i...
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- 2021
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9. Three-Dimensional Carbon Electrocatalysts for CO2 or CO Reduction
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Yan Jiao, Hao Wan, Alexander Bagger, and Jan Rossmeisl
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010405 organic chemistry ,Chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Redox ,Catalysis ,0104 chemical sciences ,Reduction (complexity) ,C c coupling ,Chemical engineering ,Density functional theory ,Carbon - Abstract
A challenge in the electrochemical CO2 reduction reaction (CO2RR) is the lack of efficient and selective electrocatalysts to valuable chemicals. Hydrocarbons and valuable chemicals from the CO2RR h...
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- 2020
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10. Catalytic CO2/CO Reduction:Gas, Aqueous, and Aprotic Phases
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Alexander Bagger, Oliver Christensen, Vladislav Ivaništšev, and Jan Rossmeisl
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aprotic ,Fischer−Tropsch ,electrochemistry ,CO reduction ,General Chemistry ,Catalysis - Abstract
The catalytic reduction of CO2/CO is key to reducing the carbon footprint and producing the chemical building blocks needed for society. In this work, we performed a theoretical investigation of the differences and similarities of the CO2/CO catalytic reduction reactions in gas, aqueous solution, and aprotic solution. We demonstrate that the binding energy serves as a good descriptor for the gaseous and aqueous phases and allows catalysts to be categorized by reduction products. The CO* vs O* and CO* vs H* binding energies for these phases give a convenient mapping of catalysts regarding their main product for the CO2/CO reduction reactions. However, for the aprotic phase, descriptors alone are insufficient for the mapping. We show that a microkinetic model (including the CO* and H* binding energies) allows spanning and interpreting the reaction space for the aprotic phase.
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- 2022
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11. Author Correction: Near ambient N2 fixation on solid electrodes versus enzymes and homogeneous catalysts
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Olivia Westhead, Jesús Barrio, Alexander Bagger, James W. Murray, Jan Rossmeisl, Maria-Magdalena Titirici, Rhodri Jervis, Andrea Fantuzzi, Andrew Ashley, and Ifan E. L. Stephens
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General Chemical Engineering ,General Chemistry - Published
- 2023
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12. High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions
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Alexander Bagger, Jack K. Pedersen, Thomas A. A. Batchelor, and Jan Rossmeisl
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Materials science ,Chemical substance ,010405 organic chemistry ,High entropy alloys ,Inorganic chemistry ,General Chemistry ,010402 general chemistry ,Electrocatalyst ,01 natural sciences ,Redox ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Carbon dioxide ,Science, technology and society ,Carbon monoxide - Abstract
We present an approach for a probabilistic and unbiased discovery of selective and active catalysts for the carbon dioxide (CO2) and carbon monoxide (CO) reduction reactions on high-entropy alloys ...
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- 2020
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13. Electrochemical CO2 Reduction: Classifying Cu Facets
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Alexander Bagger, Peter Strasser, Jan Rossmeisl, Ana Sofia Varela, and Wen Ju
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chemistry.chemical_classification ,010405 organic chemistry ,education ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Redox ,Copper ,Catalysis ,0104 chemical sciences ,Reduction (complexity) ,Hydrocarbon ,Chemical engineering ,chemistry - Abstract
For CO2 reduction reactions, the Cu catalyst is unique, as compared with other metals, because of its ability to produce a wide range of hydrocarbon and oxygenated products. Previously, we have sho...
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- 2019
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14. Electrochemical Reduction of CO2 on Metal-Nitrogen-Doped Carbon Catalysts
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Jan Rossmeisl, Alexander Bagger, Patricio Franco, Wen Ju, Ana Sofia Varela, and Peter Strasser
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Materials science ,010405 organic chemistry ,business.industry ,chemistry.chemical_element ,General Chemistry ,Chemical industry ,Raw material ,010402 general chemistry ,Electrochemistry ,Electrocatalyst ,01 natural sciences ,Redox ,Catalysis ,0104 chemical sciences ,Synthetic fuel ,Chemical engineering ,chemistry ,business ,Carbon - Abstract
The electrochemical CO2 reduction reaction (CO2RR) is a promising technology for converting waste CO2 into chemicals which could be used as feedstock for the chemical industry or as synthetic fuels...
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- 2019
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15. Electrochemical Nitric Oxide Reduction on Metal Surfaces
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Alexander Bagger, Jan Rossmeisl, and Hao Wan
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Chemistry ,Inorganic chemistry ,Ammonia Synthesis ,General Medicine ,General Chemistry ,Electrocatalyst ,Electrochemistry ,DFT ,NOx Removal ,Catalysis ,Product distribution ,Metal ,Ammonia production ,visual_art ,visual_art.visual_art_medium ,Electrocatalysis ,Selectivity ,NOx ,Metal Surfaces - Abstract
Electrocatalytic denitrifification is a promising technology for removing NOx species (NO3−, NO2− and NO). For NOx electroreduction (NOxRR), there is a desire for understanding the catalytic parameters that control the product distribution. Here, we elucidate selectivity and activity of catalyst for NOxRR. At low potential we classify metals by the binding of ∗NO versus ∗H. Analogous to classifying CO2 reduction by ∗CO vs ∗H, Cu is able to bind ∗NO while not binding ∗H giving rise to a selective NH3 formation. Besides being selective, Cu is active for the reaction found by an activity-volcano. For metals that does not bind NO the reaction stops at NO, similar to CO2-to-CO. At potential above 0.3 V vs RHE, we speculate a low barrier for N coupling with NO causing N2O formation. The work provide a clear strategy for selectivity and aims to inspire future research on NOxRR.
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- 2021
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16. Role of Catalyst in Controlling N2 Reduction Selectivity:A Unified View of Nitrogenase and Solid Electrodes
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Jan Rossmeisl, Alexander Bagger, Hao Wan, Ifan E. L. Stephens, and Commission of the European Communities
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MECHANISM ,0904 Chemical Engineering ,0305 Organic Chemistry ,Catalysis ,Reduction (complexity) ,N-2 reduction ,0302 Inorganic Chemistry ,EVOLUTION REACTION ,electrocatalysis ,PERSPECTIVE ,density functional theory ,Science & Technology ,Chemistry ,Chemistry, Physical ,Nitrogenase ,PATHWAYS ,CO reduction ,General Chemistry ,Combinatorial chemistry ,AMMONIA-SYNTHESIS ,FEMO-COFACTOR ,classification ,electrochemistry ,CO2 reduction ,Electrode ,Physical Sciences ,LIGAND ,Selectivity ,ELECTROCHEMICAL CO2 REDUCTION - Abstract
The Haber-Bosch process conventionally reduces N-2 to ammonia at 200 bar and 500 degrees C. Under ambient conditions, i.e., room temperature and ambient pressure, N-2 can be converted into ammonia by the nitrogenase molecule and lithium-containing solid electrodes in nonaqueous media. In this work, we explore the catalyst space for the N-2 reduction reaction under ambient conditions. We describe N-2 reduction on the basis of the *N-2 binding energy versus the *H binding energy; we find that under standard conditions, no catalyst can bind and reduce *N-2 without producing H-2. We show why a selective catalyst for N-2 reduction will also likely be selective for CO2 reduction, but N-2 reduction is intrinsically more challenging than CO2 reduction. Only by modulating the reaction pathway, like nitrogenase, or by tuning chemical potentials, like the Haber-Bosch and the Li-mediated process, N-2 can be reduced.
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- 2021
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17. Understanding activity and selectivity of metal-nitrogen-doped carbon catalysts for electrochemical reduction of CO2
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Jan Rossmeisl, Stefan Kaskel, Guang-Ping Hao, Beatriz Roldan Cuenya, Ilya Sinev, Peter Strasser, Alexander Bagger, Volodymyr Bon, Wen Ju, and Ana Sofia Varela
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Science ,General Physics and Astronomy ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,Electrocatalyst ,Electrochemistry ,7. Clean energy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Catalysis ,Metal ,Reactivity (chemistry) ,lcsh:Science ,chemistry.chemical_classification ,Multidisciplinary ,Chemistry ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Hydrocarbon ,Chemical engineering ,13. Climate action ,visual_art ,visual_art.visual_art_medium ,lcsh:Q ,0210 nano-technology ,Selectivity ,Carbon - Abstract
Direct electrochemical reduction of CO2 to fuels and chemicals using renewable electricity has attracted significant attention partly due to the fundamental challenges related to reactivity and selectivity, and partly due to its importance for industrial CO2-consuming gas diffusion cathodes. Here, we present advances in the understanding of trends in the CO2 to CO electrocatalysis of metal- and nitrogen-doped porous carbons containing catalytically active M–N x moieties (M = Mn, Fe, Co, Ni, Cu). We investigate their intrinsic catalytic reactivity, CO turnover frequencies, CO faradaic efficiencies and demonstrate that Fe–N–C and especially Ni–N–C catalysts rival Au- and Ag-based catalysts. We model the catalytically active M–N x moieties using density functional theory and correlate the theoretical binding energies with the experiments to give reactivity-selectivity descriptors. This gives an atomic-scale mechanistic understanding of potential-dependent CO and hydrocarbon selectivity from the M–N x moieties and it provides predictive guidelines for the rational design of selective carbon-based CO2 reduction catalysts.
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- 2017
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18. Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction
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Ana Sofia Varela, Jan Rossmeisl, Wen Ju, Peter Strasser, and Alexander Bagger
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Hydrogen ,Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Reaction intermediate ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Redox ,Catalysis ,0104 chemical sciences ,Metal ,visual_art ,visual_art.visual_art_medium ,Density functional theory ,0210 nano-technology ,Selectivity - Abstract
Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting the competing Hydrogen Evolution Reaction (HER). The single metal site in a porphyrine-like structure requires an ontop site binding of hydrogen, compared to the hollow site binding of hydrogen on a metal catalyst surface. The difference in binding site structure gives a fundamental energy-shift in the scaling relation of ∼0.3 eV between the COOH* vs. H* intermediate (CO2RR vs. HER). As a result, porphyrine-like catalysts have the advantage over metal catalyst of suppressing HER and enhancing CO2RR selectivity.
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- 2017
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19. Electrochemical CO Reduction : A Property of the Electrochemical Interface
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Jan Rossmeisl, Martin Hangaard Hansen, Alexander Bagger, Eckhard Spohr, and Logi Arnarson
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Ab initio ,Chemie ,General Chemistry ,Electrolyte ,Overpotential ,Electrochemistry ,Biochemistry ,Redox ,Catalysis ,Metal ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Chemical engineering ,chemistry ,visual_art ,visual_art.visual_art_medium ,Alkali hydroxide - Abstract
Electrochemical CO reduction holds the promise to be a cornerstone for sustainable production of fuels and chemicals. However, the underlying understanding of the carbon-carbon coupling toward multiple-carbon products is not complete. Here we present thermodynamically realistic structures of the electrochemical interfaces, determined by explicit ab initio simulations. We investigate how key CO reduction reaction intermediates are stabilized in different electrolytes and at different pH values. We find that the catalytic trends previously observed experimentally can be explained by the interplay between the metal surface and the electrolyte. For the Cu(100) facet with a phosphate buffer electrolyte, the energy efficiency is found to be limited by blocking of a phosphate anion, while in alkali hydroxide solutions (MOH, M = Na, K, Cs), OH* intermediates may be present, and at high overpotential the H* coverage limits the reaction. The results provide insight into the electrochemical interface structure, revealing the limitations for multiple-carbon products, and offer a direct comparison to experiments.
- Published
- 2019
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