6 results on '"Mikael Valter"'
Search Results
2. Solvent Effects for Methanol Electrooxidation on Gold
- Author
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Björn Wickman, Anders Hellman, and Mikael Valter
- Subjects
Reaction mechanism ,Chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Chemical engineering ,Methanol ,Physical and Theoretical Chemistry ,Solvent effects ,0210 nano-technology ,Methanol fuel - Abstract
A detailed understanding of the methanol electrooxidation reaction mechanism is important for the further development of methanol fuel cells. By modeling the reaction on Au(111) using density funct...
- Published
- 2021
3. Partial Electrooxidation of Glycerol on Close-Packed Transition Metal Surfaces: Insights from First-Principles Calculations
- Author
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Egon Campos dos Santos, Mikael Valter, Anders Hellman, and Lars G. M. Pettersson
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Standard hydrogen electrode ,Hydrogen ,Chemistry ,Inorganic chemistry ,Dihydroxyacetone ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ruthenium ,Rhodium ,Metal ,chemistry.chemical_compound ,General Energy ,Transition metal ,visual_art ,visual_art.visual_art_medium ,Reversible hydrogen electrode ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Glycerol is a byproduct of biodiesel production and an abundant feedstock for the synthesis of high-value chemicals. One promising approach for valorization of glycerol is electrooxidation yielding hydrogen and value-added products. However, due to the vast amount of intermediary steps and possible products, the process is not fully understood. Here, the first two deprotonations of glycerol on close-packed transition metals (Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au) are investigated using density functional theory calculations together with the computational hydrogen electrode. We find that the theoretical limiting potential for the studied reaction is close to 0 V vs the reversible hydrogen electrode, ranging from −0.12 V for ruthenium to +0.35 V for gold. Furthermore, the results show that Ru, Rh, Ir, Ag, and Au are selective toward dihydroxyacetone and its derivatives, while Pd and Pt are selective toward either dihydroxyacetone or glyceraldehyde and their derivatives, and that Cu, Co, and Ni are selective toward hydropyruvic acid. The results can be rationalized in terms of the relative bond strengths of carbon and oxygen on the metal. In addition, we find that solvent effects are generally small, the exceptions being the limiting potential on copper and the mechanism on rhodium. These results can be used to steer the selectivity toward more valuable products and thereby increase the economic yield of biodiesel production.
- Published
- 2020
4. Efficient Screening of Bi-Metallic Electrocatalysts for Glycerol Valorization
- Author
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Lars G. M. Pettersson, Mikael Valter, Michal Bajdich, German Salazar-Alvarez, Egon Campos dos Santos, Frank Abild-Pedersen, Rafael B. Araujo, and Mats Johnsson
- Subjects
Fysikalisk kemi ,Hydrogen ,Biodiesel Industry ,General Chemical Engineering ,chemistry.chemical_element ,Raw material ,Computational Screening Method ,Redox ,Physical Chemistry ,Bi-metallic electrodes ,Catalysis ,Microkinetic Modeling ,chemistry.chemical_compound ,Glycerol Eletrochemical Valorization ,chemistry ,Chemical engineering ,Biodiesel production ,Electrochemistry ,Glycerol ,Selectivity ,Hydrogen production - Abstract
Glycerol is a byproduct of biodiesel production and, as such, it is of limited economic value. By means of electrooxidation, glycerol can be used as a feedstock for scalable hydrogen production, in addition to conversion to value-added products. The development of novel and efficient catalytic electrode materials for the anodic side of the reaction is a key towards a hydrogen-based energy economy. In the present study, a computational screening protocol combining DFT, scaling relations, and microkinetic modeling allows for a rational selection of novel catalysts that can deliver efficient glycerol electrooxidation, low cost of production, and environmental sustainability. Activity and chemical selectivity towards hydrogen production on pure metal catalysts is discussed in terms of volcano-shaped plots. We find that the selectivity in the glycerol oxidation reaction is influenced by a different energy landscape when in the presence of water and best classified by a comparison of O-H and C-H bond-breaking barriers. In addition, we screened 3570 bi-metallic catalysts in the AB (L1(0)) and A(3)B (L1(2)) ordered structures for activity, stability, price, and toxicity. By filtering based on the criteria for toxicity, resistance to oxidation, miscibility, and price, we have identified 5 L1(0) structured catalysts (AgPd, AuPd, PtSb, CuPt, and AgPt) and 20 L1(2) catalysts (Ga3Ta, In3Ta, Ir3W, Ir3Mo, Cu3Pt, Ir3Ta, Ir3Re, Pd3Bi, Pd3Cu, Pd3W, Pd3Co, Pd3Sn, Pd3Mo, Pd3Ag, Pd3Ga, Pd3Ta, Au3Ru, Pd3In, Au3Ir, and Pd3Au) that are all predicted to show high activity. We also identify an additional 37 L1(0) and 92 L1(2) structured electrocatalysts with an anticipated medium-high activity. (C) 2021 The Author(s). Published by Elsevier Ltd.
- Published
- 2021
5. Electrooxidation of Glycerol on Gold in Acidic Medium: A Combined Experimental and DFT Study
- Author
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Anders Hellman, Jonas Baltrusaitis, Henrik Grönbeck, Björn Wickman, Michael Busch, and Mikael Valter
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Inorganic chemistry ,Dihydroxyacetone ,02 engineering and technology ,Pourbaix diagram ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,chemistry ,Glyceraldehyde ,Glycerol ,Reversible hydrogen electrode ,Dehydrogenation ,Physical and Theoretical Chemistry ,Cyclic voltammetry ,0210 nano-technology ,Carbon monoxide - Abstract
Glycerol is a byproduct of biodiesel production and an abundant feedstock for the synthesis of high-value chemicals. A promising approach for valorization of glycerol is electrooxidation on gold. In this work, we investigate electrooxidation of glycerol on gold in acidic media using cyclic voltammetry and density functional theory calculations. Experimentally, we observe activity for electrooxidation above a potential of 0.5 V versus the reversible hydrogen electrode (RHE). A Pourbaix diagram is calculated to evaluate the surface coverage under reaction conditions, indicating that the surface is free from adsorbates at the measured onset potential. Computationally, we find that the onset potentials for partial dehydrogenation of glycerol to dihydroxyacetone, 2,3-dihydroxy-2-propenal, and glyceraldehyde are 0.39, 0.39, and 0.60 V versus RHE, respectively, while complete dehydrogenation to carbon monoxide requires 0.50 V versus RHE. Our theoretical and experimental findings are in agreement and show the pos...
- Published
- 2018
6. Geometry and Electronic Properties of Glycerol Adsorbed on Bare and Transition-Metal Surface-Alloyed Au(111): A Density Functional Theory Study
- Author
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Anders Hellman, Jonas Baltrusaitis, and Mikael Valter
- Subjects
Chemical substance ,Chemistry ,Thermodynamics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface energy ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Catalysis ,symbols.namesake ,General Energy ,Adsorption ,Lattice constant ,Transition metal ,symbols ,Organic chemistry ,Density functional theory ,Physical and Theoretical Chemistry ,van der Waals force ,0210 nano-technology - Abstract
Glycerol exists in large amounts owing to its role as a byproduct in biodiesel production, and thanks to its chemical composition, it can be converted into more high-value products, such as mono- and polyethers, esters, diols, acrolein, and others. Hence, predicting glycerol-reactive properties is of utmost importance for designing efficient catalytic processes for its selective (electro)catalytic transformations; however, such an understanding is still far from complete. In this work, we performed quantum chemical calculations to validate a range of dispersion-corrected functionals to accurately predict and interpret structural, electronic, and vibrational properties of glycerol adsorbed on bare and transition-metal surface-alloyed Au(111) surface. optB86b-vdW (van der Waals) was found to have the overall best agreement with experiments concerning lattice constant, bulk stress, surface energy, and methanol adsorption among PBE (Perdew–Burke–Ernzerhof), optB88-vdW, optPBE-vdW, vdW-DF (density functional),...
- Published
- 2016
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