1
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Kastinen T, Batys P, Tolmachev D, Laasonen K, Sammalkorpi M. Ion-Specific Effects on Ion and Polyelectrolyte Solvation. Chemphyschem 2024:e202400244. [PMID: 38712639 DOI: 10.1002/cphc.202400244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 05/08/2024]
Abstract
Ion-specific effects on aqueous solvation of monovalent counter ions, Na+, K+, Cl-, and Br-, and two model polyeletrolytes (PEs), poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium) (PDADMA) were here studied with ab initio molecular dynamics (AIMD) and classical molecular dynamics (MD) simulations based on the OPLS-aa force-field which is an empirical fixed point-charge force-field. Ion-specific binding to the PE charge groups was also characterized. Both computational methods predict similar response for the solvation of the PEs but differ notably in description of ion solvation. Notably, AIMD captures the experimentally observed differences in Cl- and Br- anion solvation and binding with the PEs, while the classical MD simulations fail to differentiate the ion species response. Furthermore, the findings show that combining AIMD with the computationally less costly classical MD simulations allows benefiting from both the increased accuracy and statistics reach.
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Affiliation(s)
- Tuuva Kastinen
- Aalto-yliopisto, Department of Chemistry and Materials Science, FINLAND
| | - Piotr Batys
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, POLAND
| | - Dmitry Tolmachev
- Aalto University, Department of Chemistry and Materials Science, FINLAND
| | - Kari Laasonen
- Aalto University, Department of Chemistry and Materials Science, FINLAND
| | - Maria Sammalkorpi
- Aalto University, Department of Chemistry and Materials Science, Kemistintie 1, 02150, Espoo, FINLAND
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2
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Nechaev AA, Gonzalez G, Verma P, Peshkov VA, Bannykh A, Hashemi A, Hannonen J, Hamza A, Papai I, Laasonen K, Peljo P, Pihko PM. Exploration of Vitamin B6-Based Redox-Active Pyridinium Salts towards the Application in Aqueous Organic Flow Batteries. Chemistry 2024:e202400828. [PMID: 38640462 DOI: 10.1002/chem.202400828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/21/2024]
Abstract
Pyridoxal hydrochloride, a vitamin B6 vitamer, was synthetically converted to a series of diverse redox-active benzoyl pyridinium salts. Cyclic voltammetry studies demonstrated redox reversibility under basic conditions, and two of the most promising salts were subjected to laboratory-scale redox flow battery tests involving galvanostatic cycling at 10 mM in 0.1 M NaOH. In these tests, the battery was charged completely, corresponding to the transfer of two electrons to the electrolyte, but no discharge was observed. Both CV analysis and electrochemical simulations confirmed that the redox wave observed in the experimental voltammograms corresponds to a two-electron process. To explain the irreversibility in the battery tests, we conducted bulk electrolysis with the benzoyl pyridinium salts, affording the corresponding benzylic secondary alcohols. Computational studies suggest that the reduction proceeds in three consecutive steps: first electron transfer (ET), then proton-coupled electron transfer (PCET) and finally proton transfer (PT) to give the secondary alcohol. 1H NMR deuterium exchange studies indicated that the last PT step is not reversible in 0.1 M NaOH, rendering the entire redox process irreversible. The apparent reversibility observed in CV at the basic media likely arises from the slow rate of the PT step at the timescale of the measurement.
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Affiliation(s)
- Anton A Nechaev
- University of Jyväskylä, Department of Chemistry, 40014, Jyväskylä, FINLAND
| | - Gabriel Gonzalez
- University of Turku, Department of Mechanical and Materials Engineering, 20014, Turku, FINLAND
| | - Prachi Verma
- University of Jyväskylä, Department of Chemistry, 40014, Jyväskylä, FINLAND
| | - Vsevolod A Peshkov
- University of Jyväskylä, Department of Chemistry, 40014, Jyväskylä, FINLAND
| | - Anton Bannykh
- University of Jyväskylä, Department of Chemistry, 40014, Jyväskylä, FINLAND
| | - Arsalan Hashemi
- Aalto University, Department of Chemistry and Material Science, 02150, Espoo, FINLAND
| | - Jenna Hannonen
- University of Turku, Department of Mechanical and Materials Engineering, 20014, Turku, FINLAND
| | - Andrea Hamza
- MTA Research Centre for Natural Sciences, Institute of Organic Chemistry, 1117, Budapest, HUNGARY
| | - Imre Papai
- MTA Research Centre for Natural Sciences, Institute of Organic Chemistry, 1117, Budapest, HUNGARY
| | - Kari Laasonen
- Aalto University, Department of Chemistry and Material Science, 02150, Espoo, FINLAND
| | - Pekka Peljo
- University of Turku, Department of Mechanical and Materials Engineering, 20014, Turku, FINLAND
| | - Petri M Pihko
- University of Jyvaskyla, Department of Chemistry, Survontie 9, P.O.B. 35, FIN-40014 JYU, Jyväskylä, FINLAND
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3
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Farshadfar K, Laasonen K. DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H 2O 2. Inorg Chem 2024; 63:5509-5519. [PMID: 38471975 DOI: 10.1021/acs.inorgchem.3c04461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Introduction of oxygen into aromatic C-H bonds is intriguing from both fundamental and practical perspectives. Although the 3d metal-catalyzed hydroxylation of arenes by H2O2 has been developed by several prominent researchers, a definitive mechanism for these crucial transformations remains elusive. Herein, density functional theory calculations were used to shed light on the mechanism of the established hydroxylation reaction of benzene with H2O2, catalyzed by [NiII(tepa)]2+ (tepa = tris[2-(pyridin-2-yl)ethyl]amine). Dinickel(III) bis(μ-oxo) species have been proposed as the key intermediate responsible for the benzene hydroxylation reaction. Our findings indicate that while the dinickel dioxygen species can be generated as a stable structure, it cannot serve as an active catalyst in this transformation. The calculations allowed us to unveil an unprecedented mechanism composed of six main steps as follows: (i) deprotonation of coordinated H2O2, (ii) oxidative addition, (iii) water elimination, (iv) benzene addition, (v) ketone generation, and (vi) tautomerization and regeneration of the active catalyst. Addition of benzene to oxygen, which occurs via a radical mechanism, turns out to be the rate-determining step in the overall reaction. This study demonstrates the critical role of Ni-oxyl species in such transformations, highlighting how the unpaired spin density value on oxygen and positive charges on the Ni-O• complex affect the activation barrier for benzene addition.
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Affiliation(s)
- Kaveh Farshadfar
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Kari Laasonen
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
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4
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Farshadfar K, Hashemi A, Khakpour R, Laasonen K. Kinetics of N 2 Release from Diazo Compounds: A Combined Machine Learning-Density Functional Theory Study. ACS Omega 2024; 9:1106-1112. [PMID: 38222626 PMCID: PMC10785077 DOI: 10.1021/acsomega.3c07367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 11/10/2023] [Accepted: 11/28/2023] [Indexed: 01/16/2024]
Abstract
Diazo compounds are commonly employed as carbene precursors in carbene transfer reactions during a variety of functionalization procedures. Release of N2 gas from diazo compounds may lead to carbene formation, and the ease of this process is highly dependent on the characteristics of the substituents located in the vicinity of the diazo moiety. A quantum mechanical density functional theory assisted by machine learning was used to investigate the relationship between the chemical features of diazo compounds and the activation energy required for N2 elimination. Our results suggest that diazo molecules, possessing a higher positive partial charge on the carbene carbon and more negative charge on the terminal nitrogen, encounter a lower energy barrier. A more positive C charge decreases the π-donor ability of the carbene lone pair to the π* orbital of N2, while the more negative N charge is a result of a weak interaction between N2 lone pair and vacant p orbital of the carbene. The findings of this study can pave the way for molecular engineering for the purpose of carbene generation, which serves as a crucial intermediate for many chemical transformations in synthetic chemistry.
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Affiliation(s)
- Kaveh Farshadfar
- Department of Chemistry and Material
Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Arsalan Hashemi
- Department of Chemistry and Material
Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Reza Khakpour
- Department of Chemistry and Material
Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Kari Laasonen
- Department of Chemistry and Material
Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
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5
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Hashemi A, Khakpour R, Mahdian A, Busch M, Peljo P, Laasonen K. Density functional theory and machine learning for electrochemical square-scheme prediction: an application to quinone-type molecules relevant to redox flow batteries. Digit Discov 2023; 2:1565-1576. [PMID: 38013904 PMCID: PMC10561546 DOI: 10.1039/d3dd00091e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 09/11/2023] [Indexed: 11/29/2023]
Abstract
Proton-electron transfer (PET) reactions are rather common in chemistry and crucial in energy storage applications. How electrons and protons are involved or which mechanism dominates is strongly molecule and pH dependent. Quantum chemical methods can be used to assess redox potential (Ered.) and acidity constant (pKa) values but the computations are rather time consuming. In this work, supervised machine learning (ML) models are used to predict PET reactions and analyze molecular space. The data for ML have been created by density functional theory (DFT) calculations. Random forest regression models are trained and tested on a dataset that we created. The dataset contains more than 8200 quinone-type organic molecules that each underwent two proton and two electron transfer reactions. Both structural and chemical descriptors are used. The HOMO of the reactant and LUMO of the product participating in the oxidation reaction appeared to be strongly associated with Ered.. Trained models using a SMILES-based structural descriptor can efficiently predict the pKa and Ered. with a mean absolute error of less than 1 and 66 mV, respectively. Good prediction accuracy of R2 > 0.76 and >0.90 was also obtained on the external test set for Ered. and pKa, respectively. This hybrid DFT-ML study can be applied to speed up the screening of quinone-type molecules for energy storage and other applications.
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Affiliation(s)
- Arsalan Hashemi
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Reza Khakpour
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Amir Mahdian
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Michael Busch
- Institute of Theoretical Chemistry, Ulm University Albert-Einstein Allee 11 89069 Ulm Germany
| | - Pekka Peljo
- Research Group of Battery Materials and Technologies, Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku 20014 Turun Yliopisto Finland
| | - Kari Laasonen
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
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6
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Hashemi A, Peljo P, Laasonen K. Understanding Electron Transfer Reactions Using Constrained Density Functional Theory: Complications Due to Surface Interactions. J Phys Chem C Nanomater Interfaces 2023; 127:3398-3407. [PMID: 36865990 PMCID: PMC9969872 DOI: 10.1021/acs.jpcc.2c06537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/25/2023] [Indexed: 06/18/2023]
Abstract
The kinetic rates of electrochemical reactions depend on electrodes and molecules in question. In a flow battery, where the electrolyte molecules are charged and discharged on the electrodes, the efficiency of the electron transfer is of crucial importance for the performance of the device. The purpose of this work is to present a systematic atomic-level computational protocol for studying electron transfer between electrolyte and electrode. The computations are done by using constrained density functional theory (CDFT) to ensure that the electron is either on the electrode or in the electrolyte. The ab initio molecular dynamics (AIMD) is used to simulate the movement of the atoms. We use the Marcus theory to predict electron transfer rates and the combined CDFT-AIMD approach to compute the parameters for the Marcus theory where it is needed. We model the electrode with a single layer of graphene and methylviologen, 4,4'-dimethyldiquat, desalted basic red 5, 2-hydroxy-1,4-naphthaquinone, and 1,1-di(2-ethanol)-4,4-bipyridinium were selected for the electrolyte molecules. All of these molecules undergo consecutive electrochemical reactions with one electron being transferred at each stage. Because of significant electrode-molecule interactions, it is not possible to evaluate outer-sphere ET. This theoretical study contributes toward the development of a realistic-level prediction of electron transfer kinetics suitable for energy storage applications.
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Affiliation(s)
- Arsalan Hashemi
- Research
Group of Computational Chemistry, Department of Chemistry and Materials
Science, Aalto University, FI-00076 Aalto, Finland
| | - Pekka Peljo
- Research
Group of Battery Materials and Technologies, Department of Mechanical
and Materials Engineering, Faculty of Technology, University of Turku, 20014 Turun Yliopisto, Finland
| | - Kari Laasonen
- Research
Group of Computational Chemistry, Department of Chemistry and Materials
Science, Aalto University, FI-00076 Aalto, Finland
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7
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Khakpour R, Lindberg D, Laasonen K, Busch M. CO2 or Carbonates – What is the Active Species in Electrochemical CO2 Reduction over Fe Porphyrin? ChemCatChem 2023. [DOI: 10.1002/cctc.202201671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Reza Khakpour
- Aalto-yliopisto Department of Chemistry and Material Science FINLAND
| | - Daniel Lindberg
- Aalto-yliopisto Department of Chemical and Metallurgical Engineering FINLAND
| | - Kari Laasonen
- Aalto-yliopisto Department of Chemistry and Material Science FINLAND
| | - Michael Busch
- Ulm University: Universitat Ulm Institute of Theoretical Chemistry Albert-Einstein Allee 11 89069 Ulm GERMANY
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8
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Hossain MN, Khakpour R, Busch M, Suominen M, Laasonen K, Kallio T. Temperature-Controlled Syngas Production via Electrochemical CO 2 Reduction on a CoTPP/MWCNT Composite in a Flow Cell. ACS Appl Energy Mater 2023; 6:267-277. [PMID: 36644114 PMCID: PMC9832436 DOI: 10.1021/acsaem.2c02873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
The mixture of CO and H2, known as syngas, is a building block for many substantial chemicals and fuels. Electrochemical reduction of CO2 and H2O to syngas would be a promising alternative approach for its synthesis due to negative carbon emission footprint when using renewable energy to power the reaction. Herein, we present temperature-controlled syngas production by electrochemical CO2 and H2O reduction on a cobalt tetraphenylporphyrin/multiwalled carbon nanotube (CoTPP/MWCNT) composite in a flow cell in the temperature range of 20-50 °C. The experimental results show that for all the applied potentials the ratio of H2/CO increases with increasing temperature. Interestingly, at -0.6 V RHE and 40 °C, the H2/CO ratio reaches a value of 1.2 which is essential for the synthesis of oxo-alcohols. In addition, at -1.0 V RHE and 20 °C, the composite shows very high selectivity toward CO formation, reaching a Faradaic efficiency of ca. 98%. This high selectivity of CO formation is investigated by density functional theory modeling which underlines that the potential-induced oxidation states of the CoTPP catalyst play a vital role in the high selectivity of CO production. Furthermore, the stability of the formed intermediate species is evaluated in terms of the pKa value for further reactions. These experimental and theoretical findings would provide an alternative way for syngas production and help us to understand the mechanism of molecular catalysts in dynamic conditions.
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9
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Busch M, Ahlberg E, Laasonen K. Universal Trends between Acid Dissociation Constants in Protic and Aprotic Solvents. Chemistry 2022; 28:e202201667. [PMID: 35791810 DOI: 10.1002/chem.202201667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Indexed: 01/07/2023]
Abstract
pKa values in non-aqueous solvents are of critical importance in many areas of chemistry. Our knowledge is, despite their relevance, still limited to the most fundamental properties and few pKa values in the most common solvents. Taking advantage of a recently introduced computationally efficient procedure we computed the pKa values of 182 compounds in 21 solvents. This data set is used to establish for the first time universal trends between all solvents. Our computations indicate, that the total charge of the molecule and the charge of the acidic group combined with the Kamlet-Taft solvatochromic parameters are sufficient to predict pKa values with at least semi- quantitative accuracy. We find, that neutral acids such as alcohols are strongly affected by the solvent properties. This is contrasted by cationic acids like ammonium ions whose pKa is often almost completely independent from the choice of solvent.
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Affiliation(s)
- Michael Busch
- Institute of theoretical chemistry, Ulm University, Albert-Einstein Allee 11, 89069, Ulm, Germany
- Department of chemistry and material science, School of chemical engineering, Aalto University, Kemistintie 1, 02150, Espoo, Finland
| | - Elisabet Ahlberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296, Gothenburg, Sweden
| | - Kari Laasonen
- Department of chemistry and material science, School of chemical engineering, Aalto University, Kemistintie 1, 02150, Espoo, Finland
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10
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Kloppenburg J, Pedersen A, Laasonen K, Caro MA, Jónsson H. Reassignment of magic numbers for icosahedral Au clusters: 310, 564, 928 and 1426. Nanoscale 2022; 14:9053-9060. [PMID: 35704390 DOI: 10.1039/d2nr01763f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Icosahedral Au clusters with three and four shells of atoms are found to deviate significantly from the commonly assumed Mackay structures. By introducing additional atoms in the surface shell and creating a vacancy in the center of the cluster, the calculated energy per atom can be lowered significantly, according to several different descriptions of the interatomic interaction. Analogous icosahedral structures with five and six shells of atoms are generated using the same structural motifs and are similarly found to be more stable than Mackay icosahedra. The lowest energy per atom obtained here is for clusters containing 310, 564, 928 and 1426 atoms, as compared with the commonly assumed magic numbers of 309, 561, 923 and 1415. Some of the vertices in the optimized clusters have a hexagonal ring of atoms, rather than a pentagon, with the vertex atom missing. An inner shell atom in some cases moves outwards by more than an Ångström into the surface shell at such a vertex site. This feature, as well as the wide distribution of nearest-neighbor distances in the surface layer, can strongly influence the properties of icosahedral clusters, for example catalytic activity. The structural optimization is initially carried out using the GOUST method with atomic forces estimated with the EMT empirical potential function, but the atomic coordinates are then refined by minimization using electron density functional theory (DFT) or Gaussian approximation potential (GAP). A single energy barrier is found to separate the Mackay icosahedron from a lower energy structure where a string of atoms moves outwards in a concerted manner from the center so as to create a central vacancy while placing an additional atom in the surface shell.
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Affiliation(s)
- Jan Kloppenburg
- Department of Electrical Engineering and Automation, Aalto University, FIN-02150 Aalto, Finland
| | - Andreas Pedersen
- Science Institute and Faculty of Physical Sciences, University of Iceland VR-III, 107 Reykjavík, Iceland.
| | - Kari Laasonen
- Department of Chemistry and Materials Science, Aalto University, FI-00076 Aalto, Finland
| | - Miguel A Caro
- Department of Electrical Engineering and Automation, Aalto University, FIN-02150 Aalto, Finland
| | - Hannes Jónsson
- Science Institute and Faculty of Physical Sciences, University of Iceland VR-III, 107 Reykjavík, Iceland.
- Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
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Busch M, Ahlberg E, Ahlberg E, Laasonen K. How to Predict the p K a of Any Compound in Any Solvent. ACS Omega 2022; 7:17369-17383. [PMID: 35647457 PMCID: PMC9134414 DOI: 10.1021/acsomega.2c01393] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Acid-base properties of molecules in nonaqueous solvents are of critical importance for almost all areas of chemistry. Despite this very high relevance, our knowledge is still mostly limited to the pK a of rather few compounds in the most common solvents, and a simple yet truly general computational procedure to predict pK a's of any compound in any solvent is still missing. In this contribution, we describe such a procedure. Our method requires only the experimental pK a of a reference compound in water and a few standard quantum-chemical calculations. This method is tested through computing the proton solvation energy in 39 solvents and by comparing the pK a of 142 simple compounds in 12 solvents. Our computations indicate that the method to compute the proton solvation energy is robust with respect to the detailed computational setup and the construction of the solvation model. The unscaled pK a's computed using an implicit solvation model on the other hand differ significantly from the experimental data. These differences are partly associated with the poor quality of the experimental data and the well-known shortcomings of implicit solvation models. General linear scaling relationships to correct this error are suggested for protic and aprotic media. Using these relationships, the deviations between experiment and computations drop to a level comparable to that observed in water, which highlights the efficiency of our method.
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Affiliation(s)
- Michael Busch
- Department
of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland
| | - Ernst Ahlberg
- Universal
Prediction AB, 42677 Gothenburg, Sweden
- Department
of Pharmaceutical Biosciences, Uppsala University, Husargatan 3, 75124 Uppsala, Sweden
| | - Elisabet Ahlberg
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, Kemigården 4, 41296 Gothenburg, Sweden
| | - Kari Laasonen
- Department
of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland
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12
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Grebenko AK, Krasnikov DV, Bubis AV, Stolyarov VS, Vyalikh DV, Makarova AA, Fedorov A, Aitkulova A, Alekseeva AA, Gilshtein E, Bedran Z, Shmakov AN, Alyabyeva L, Mozhchil RN, Ionov AM, Gorshunov BP, Laasonen K, Podzorov V, Nasibulin AG. High-Quality Graphene Using Boudouard Reaction. Adv Sci (Weinh) 2022; 9:e2200217. [PMID: 35187847 PMCID: PMC9036046 DOI: 10.1002/advs.202200217] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 01/29/2022] [Indexed: 06/02/2023]
Abstract
Following the game-changing high-pressure CO (HiPco) process that established the first facile route toward large-scale production of single-walled carbon nanotubes, CO synthesis of cm-sized graphene crystals of ultra-high purity grown during tens of minutes is proposed. The Boudouard reaction serves for the first time to produce individual monolayer structures on the surface of a metal catalyst, thereby providing a chemical vapor deposition technique free from molecular and atomic hydrogen as well as vacuum conditions. This approach facilitates inhibition of the graphene nucleation from the CO/CO2 mixture and maintains a high growth rate of graphene seeds reaching large-scale monocrystals. Unique features of the Boudouard reaction coupled with CO-driven catalyst engineering ensure not only suppression of the second layer growth but also provide a simple and reliable technique for surface cleaning. Aside from being a novel carbon source, carbon monoxide ensures peculiar modification of catalyst and in general opens avenues for breakthrough graphene-catalyst composite production.
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Affiliation(s)
- Artem K. Grebenko
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
- Moscow Institute of Physics and TechnologyInstitute Lane 9DolgoprudnyRussia
| | | | - Anton V. Bubis
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
- Insitute of Solid State Physics (RAS)Academician Ossupyan str. 2ChernogolovkaRussia
| | - Vasily S. Stolyarov
- Moscow Institute of Physics and TechnologyInstitute Lane 9DolgoprudnyRussia
- Dukhov Research Institute of Automatics (VNIIA)Moscow127055Russia
- National University of Science and Technology MISISMoscow119049Russia
| | - Denis V. Vyalikh
- Donostia International Physics Center (DIPC)Donostia‐San Sebastián20018Spain
- IKERBASQUEBasque Foundation for ScienceBilbao48011Spain
| | - Anna A. Makarova
- Physikalische ChemieInstitut für Chemie und BiochemieFreie Universität BerlinArnimallee 22Berlin14195Germany
| | | | - Aisuluu Aitkulova
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
| | - Alena A. Alekseeva
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
| | - Evgeniia Gilshtein
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
- EmpaSwiss Federal Laboratories for Materials Science and TechnologyUeberlandstrasse 129Duebendorf8600Switzerland
| | - Zakhar Bedran
- Moscow Institute of Physics and TechnologyInstitute Lane 9DolgoprudnyRussia
| | | | - Liudmila Alyabyeva
- Moscow Institute of Physics and TechnologyInstitute Lane 9DolgoprudnyRussia
| | - Rais N. Mozhchil
- Insitute of Solid State Physics (RAS)Academician Ossupyan str. 2ChernogolovkaRussia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)Moscow115409Russia
| | - Andrey M. Ionov
- Insitute of Solid State Physics (RAS)Academician Ossupyan str. 2ChernogolovkaRussia
- HSE UniversityMyasnitskaya 20Moscow101000Russia
| | - Boris P. Gorshunov
- Moscow Institute of Physics and TechnologyInstitute Lane 9DolgoprudnyRussia
| | | | | | - Albert G. Nasibulin
- Skolkovo Institute of Science and TechnologyNobel str. 3Moscow121205Russia
- Aalto UniversityP.O. Box 16100AaltoFI‐00076Finland
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13
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Kronberg R, Laasonen K. Dynamics and Surface Propensity of H + and OH - within Rigid Interfacial Water: Implications for Electrocatalysis. J Phys Chem Lett 2021; 12:10128-10134. [PMID: 34636561 PMCID: PMC8543677 DOI: 10.1021/acs.jpclett.1c02493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
Facile solvent reorganization promoting ion transfer across the solid-liquid interface is considered a prerequisite for efficient electrocatalysis. We provide first-principles insight into this notion by examining water self-ion dynamics at a highly rigid NaCl(100)-water interface. Through extensive density functional theory molecular dynamics simulations, we demonstrate for both acidic and alkaline solutions that Grotthuss dynamics is not impeded by a rigid water structure. Conversely, decreased proton transfer barriers and a striking propensity of H3O+ and OH- for stationary interfacial water are found. Differences in the ideal hydration structure of the ions, however, distinguish their behavior at the water contact layer. While hydronium can maintain its optimal solvation, the preferentially hypercoordinated hydroxide is repelled from the immediate vicinity of the surface due to interfacial coordination reduction. This has implications for alkaline hydrogen electrosorption in which the formation of undercoordinated OH- at the surface is proposed to contribute to the observed sluggish kinetics.
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14
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Kronberg R, Laasonen K. Reconciling the Experimental and Computational Hydrogen Evolution Activities of Pt(111) through DFT-Based Constrained MD Simulations. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00538] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Rasmus Kronberg
- Research Group of Computational Chemistry, Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- Research Group of Computational Chemistry, Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
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15
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Busch M, Ahlberg E, Laasonen K. From absolute potentials to a generalized computational standard hydrogen electrode for aqueous and non-aqueous solvents. Phys Chem Chem Phys 2021; 23:11727-11737. [PMID: 33982050 DOI: 10.1039/d1cp00499a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We describe a simple and efficient procedure to compute a conversion factor for the absolute potential of the standard hydrogen electrode in water to any other solvent. In contrast to earlier methods our procedure only requires the pKa of an arbitrary acid in water and few simple quantum chemical calculations as input. Thus, it is not affected adversely by experimental shortcomings related to measurements in non-aqueous solvents. By combining this conversion factor with the absolute potential in water, the absolute potential in the solvent of interest is obtained. Based on this procedure a new generalized computational standard hydrogen electrode for the computation of electron transfer and proton-coupled electron transfer potentials in non-aqueous solvents and ionic liquids is developed. This enables for the first time the reliable prediction of redox potentials in any solvent. The method is tested through calculation of absolute potentials in 36 solvents. Using the Kamlet-Taft linear solvation energy model we find that the relative absolute potentials consistently increase with decreasing polarisability and decreasing hydrogen bonding ability. For protic solvents good agreement with literature is observed while significant deviations are found for aprotic solvents. The obtained conversion factors are independent of the quantum chemical method, while minor differences are observed between solvation models. This does, however, not affect the global trends.
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Affiliation(s)
- Michael Busch
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University Kemistintie 1, 02150 Espoo, Finland.
| | - Elisabet Ahlberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Gothenburg, Sweden
| | - Kari Laasonen
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University Kemistintie 1, 02150 Espoo, Finland.
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16
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Partanen L, Alberti S, Laasonen K. Hydrogen adsorption trends on two metal-doped Ni 2P surfaces for optimal catalyst design. Phys Chem Chem Phys 2021; 23:11538-11547. [PMID: 33969865 DOI: 10.1039/d1cp00684c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, we looked at the hydrogen evolution reaction on the doubly doped Ni3P2 terminated Ni2P surface. Two Ni atoms in the first three layers of the Ni2P surface model were exchanged with two transition metal atoms. We limited our investigation to combinations of Al, Co, and Fe based on their individual effectiveness as Ni2P dopants in our previous computational studies. The DFT calculated hydrogen adsorption free energy was employed as a predictor of the materials' catalytic HER activity. Our results indicate that the combination of Co and Fe dopants most improves the catalytic activity of the surface through the creation of multiple novel and active catalytic sites.
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Affiliation(s)
- Lauri Partanen
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
| | - Simon Alberti
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
| | - Kari Laasonen
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
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17
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Busch M, Laasonen K, Ahlberg E. Method for the accurate prediction of electron transfer potentials using an effective absolute potential. Phys Chem Chem Phys 2020; 22:25833-25840. [PMID: 33150898 DOI: 10.1039/d0cp04508j] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A protocol for the accurate computation of electron transfer (ET) potentials from ab initio and density functional theory (DFT) calculations is described. The method relies on experimental pKa values, which can be measured accurately, to compute a computational setup dependent effective absolute potential. The effective absolute potentials calculated using this protocol display strong variations between the different computational setups and deviate in several cases significantly from the "generally accepted" value of 4.28 V. The most accurate estimate, obtained from CCSD(T)/aug-ccpvqz, indicates an absolute potential of 4.14 V for the normal hydrogen electrode (nhe) in water. Using the effective absolute potential in combination with CCSD(T) and a moderately sized basis, we are able to predict ET potentials accurately for a test set of small organic molecules (σ = 0.13 V). Similarly we find the effective absolute potential method to perform equally good or better for all considered DFT functionals compared to using one of the literature values for the absolute potential. For, M06-2X, which comprises the most accurate DFT method, standard deviation of 0.18 V is obtained. This improved performance is a result of using the most appropriate effective absolute potential for a given method.
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Affiliation(s)
- Michael Busch
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University Kemistintie 1, 02150 Espoo, Finland.
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18
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Younus HA, Zhang Y, Vandichel M, Ahmad N, Laasonen K, Verpoort F, Zhang C, Zhang S. Water Oxidation at Neutral pH using a Highly Active Copper-Based Electrocatalyst. ChemSusChem 2020; 13:5088-5099. [PMID: 32667741 DOI: 10.1002/cssc.202001444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Indexed: 06/11/2023]
Abstract
The sluggish kinetics of the oxygen evolution reaction (OER) at the anode severely limit hydrogen production at the cathode in water splitting systems. Although electrocatalytic systems based on cheap and earth-abundant copper catalysts have shown promise for water oxidation under basic conditions, only very few examples with high overpotential can be operated under acidic or neutral conditions, even though hydrogen evolution in the latter case is much easier. This work presents an efficient and robust Cu-based molecular catalyst, which self-assembles as a periodic film from its precursors under aqueous conditions on the surface of a glassy carbon electrode. This film catalyzes the OER under neutral conditions with impressively low overpotential. In controlled potential electrolysis, a stable catalytic current of 1.0 mA cm-2 can be achieved at only 2.0 V (vs. RHE) and no significant decrease in the catalytic current is observed even after prolonged bulk electrolysis. The catalyst displays first-order kinetics and a single site mechanism for water oxidation with a TOF (kcat ) of 0.6 s-1 . DFT calculations on of the periodic Cu(TCA)2 (HTCA=1-mesityl-1H-1,2,3-triazole-4-carboxylic acid) film reveal that TCA defects within the film create CuI active sites that provide a low overpotential route for OER, which involves CuI , CuII -OH, CuIII =O and CuII -OOH intermediates and is enabled at a potential of 1.54 V (vs. RHE), requiring an overpotential of 0.31 V. This corresponds well with an overpotential of approximately 0.29 V obtained experimentally for the grown catalytic film after 100 CV cycles at pH 6. However, to reach a higher current density of 1 mA cm-2 , an overpotential of 0.72 V is required.
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Affiliation(s)
- Hussein A Younus
- College of Materials Science and Engineering, Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, Hunan University, Changsha, 410082, P. R. China
- Chemistry Department, Faculty of Science, Fayoum University, Fayoum, 63514, Egypt
| | - Yan Zhang
- College of Materials Science and Engineering, Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, Hunan University, Changsha, 410082, P. R. China
| | - Matthias Vandichel
- Department of Chemical Sciences and Bernal Institute, University of Limerick, Limerick, V94 T9PX, Republic of Ireland
- School of Chemical Engineering, Aalto University, 02150, Espoo, Finland
| | - Nazir Ahmad
- Department of Chemistry, GC University, Lahore, 54000, Pakistan
| | - Kari Laasonen
- School of Chemical Engineering, Aalto University, 02150, Espoo, Finland
| | - Francis Verpoort
- Laboratory of Organometallics, Catalysis and Ordered Materials, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, P. R. China
| | - Ce Zhang
- Nanophotonics and Optoelectronics Research Center, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing, 100094, P. R. China
| | - Shiguo Zhang
- College of Materials Science and Engineering, Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, Hunan University, Changsha, 410082, P. R. China
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19
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Vandichel M, Laasonen K, Kondov I. Oxygen Evolution and Reduction on Fe-doped NiOOH: Influence of Solvent, Dopant Position and Reaction Mechanism. Top Catal 2020. [DOI: 10.1007/s11244-020-01334-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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Kronberg R, Lappalainen H, Laasonen K. Revisiting the Volmer-Heyrovský mechanism of hydrogen evolution on a nitrogen doped carbon nanotube: constrained molecular dynamics versus the nudged elastic band method. Phys Chem Chem Phys 2020; 22:10536-10549. [PMID: 31998914 DOI: 10.1039/c9cp06474e] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Density functional theory (DFT) based computational electrochemistry has the potential to serve as a tool with predictive power in the rational development and screening of electrocatalysts for renewable energy technologies. It is, however, of paramount importance that simulations are conducted rigorously at a level of theory that is sufficiently accurate in order to obtain physicochemically sensible results. Herein, we present a comparative study of the performance of the static climbing image nudged elastic band method (CI-NEB) vs. DFT based constrained molecular dynamics simulations with thermodynamic integration in estimating activation and reaction (free) energies of the Volmer-Heyrovský mechanism on a nitrogen doped carbon nanotube. Due to cancellation of errors within the CI-NEB calculations, static and dynamic activation barriers are observed to be surprisingly similar, while a substantial decrease in reaction energies is seen upon incorporation of solvent dynamics. This finding is attributed to two competing effects; (1) solvent reorganization that stabilizes the transition and, in particular, the product states with respect to the reactant state and (2) destabilizing entropic contributions due to solvent fluctuations. Our results highlight the importance of explicitly sampling the interfacial solvent dynamics when studying hydrogen evolution at solid-liquid interfaces.
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Affiliation(s)
- Rasmus Kronberg
- Research Group of Computational Chemistry, Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
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21
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Humphrey JJL, Kronberg R, Cai R, Laasonen K, Palmer RE, Wain AJ. Active site manipulation in MoS 2 cluster electrocatalysts by transition metal doping. Nanoscale 2020; 12:4459-4472. [PMID: 32030382 DOI: 10.1039/c9nr10702a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The development of non-platinum group metal catalysts for the hydrogen evolution reaction (HER) in water electrolyser devices is essential for their widespread and sustainable deployment. In recent years, molybdenum disulfide (MoS2) catalysts have received significant attention as they not only exhibit good electrocatalytic HER activity but also, crucially, acid-stability. However, further performance enhancement is required for these materials to be competitive with Pt and to that end transition metal doping of MoS2 has been explored as a route to further increasing its catalytic activity. In this work, cluster beam deposition was employed to produce controlled cobalt-doped MoS2 clusters (MoS2-Co). We demonstrate that, in contrast to previous observations of performance enhancement in MoS2 resulting from nickel doping (MoS2-Ni), the introduction of Co has a detrimental effect on HER activity. The contrasting behaviours of Ni and Co doping are rationalized by density functional theory (DFT) calculations, which suggest that HER-active surface vacancies are deactivated by combination with Co dopant atoms, whilst their activity is retained, or even partially enhanced, by combination with Ni dopant atoms. Furthermore, the adatom dopant-vacancy combination kinetics appear to be more than three orders of magnitude faster in MoS2-Co than for MoS2-Ni. These findings highlight a fundamental difference in the influence of transition metal dopants on the HER performance of MoS2 electrocatalysts and stress the importance of considering surface atomic defects when predicting their behaviour.
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Affiliation(s)
- Jo J L Humphrey
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.
| | - Rasmus Kronberg
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Rongsheng Cai
- College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK
| | - Kari Laasonen
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Richard E Palmer
- College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK
| | - Andrew J Wain
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.
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22
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Vandichel M, Busch M, Laasonen K. Oxygen Evolution on Metal‐oxy‐hydroxides: Beneficial Role of Mixing Fe, Co, Ni Explained via Bifunctional Edge/acceptor Route. ChemCatChem 2020. [DOI: 10.1002/cctc.201901951] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Matthias Vandichel
- Department of chemistry and material science School of chemical engineeringAalto University Kemistintie 1 02150 Espoo Finland
- Department of Chemical Sciences and Bernal InstituteUniversity of Limerick Limerick Ireland
- Department of applied physicsAalto University Otakaari 1 02150 Espoo Finland
| | - Michael Busch
- Department of chemistry and material science School of chemical engineeringAalto University Kemistintie 1 02150 Espoo Finland
| | - Kari Laasonen
- Department of chemistry and material science School of chemical engineeringAalto University Kemistintie 1 02150 Espoo Finland
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23
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Partanen L, Hakala M, Laasonen K. Hydrogen adsorption trends on various metal-doped Ni2P surfaces for optimal catalyst design. Phys Chem Chem Phys 2019; 21:184-191. [DOI: 10.1039/c8cp06143b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article shows that the presence of dopants, especially Fe and Co, can enhance the HER catalytic activity of Ni2P.
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Affiliation(s)
- Lauri Partanen
- Department of Chemistry and Materials Science, Aalto University
- FI-00076 Aalto
- Finland
| | - Mikko Hakala
- Department of Chemistry and Materials Science, Aalto University
- FI-00076 Aalto
- Finland
| | - Kari Laasonen
- Department of Chemistry and Materials Science, Aalto University
- FI-00076 Aalto
- Finland
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24
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Murdachaew G, Laasonen K. Oxygen Evolution Reaction on Nitrogen-Doped Defective Carbon Nanotubes and Graphene. J Phys Chem C Nanomater Interfaces 2018; 122:25882-25892. [PMID: 30467515 PMCID: PMC6240890 DOI: 10.1021/acs.jpcc.8b08519] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/19/2018] [Indexed: 05/31/2023]
Abstract
The realization of a hydrogen economy would be facilitated by the discovery of a water-splitting electrocatalyst that is efficient, stable under operating conditions, and composed of earth-abundant elements. Density functional theory simulations within a simple thermodynamic model of the more difficult half-reaction, the anodic oxygen evolution reaction (OER), with a single-walled carbon nanotube as a model catalyst, show that the presence of 0.3-1% nitrogen reduces the required OER overpotential significantly compared to the pristine nanotube. We performed an extensive exploration of systems and active sites with various nitrogen functionalities (graphitic, pyridinic, or pyrrolic) obtained by introducing nitrogen and simple lattice defects (atomic substitutions, vacancies, or Stone-Wales rotations). A number of nitrogen functionalities (graphitic, oxidized pyridinic, and Stone-Wales pyrrolic nitrogen systems) yielded similar low overpotentials near the top of the OER volcano predicted by the scaling relation, which was seen to be closely observed by these systems. The OER mechanism considered was the four-step single-site water nucleophilic attack mechanism. In the active systems, the second or third step, the formation of attached oxo or peroxo moieties, was the potential-determining step of the reaction. The nanotube radius and chirality effects were examined by considering OER in the limit of large radius by studying the analogous graphene-based model systems. They exhibited trends similar to those of the nanotube-based systems but often with reduced reactivity due to weaker attachment of the OER intermediate moieties.
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25
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Holmberg N, Laasonen K. Diabatic model for electrochemical hydrogen evolution based on constrained DFT configuration interaction. J Chem Phys 2018; 149:104702. [PMID: 30219020 DOI: 10.1063/1.5038959] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The accuracy of density functional theory (DFT) based kinetic models for electrocatalysis is diminished by spurious electron delocalization effects, which manifest as uncertainties in the predicted values of reaction and activation energies. In this work, we present a constrained DFT (CDFT) approach to alleviate overdelocalization effects in the Volmer-Heyrovsky mechanism of the hydrogen evolution reaction (HER). This method is applied a posteriori to configurations sampled along a reaction path to correct their relative stabilities. Concretely, the first step of this approach involves describing the reaction in terms of a set of diabatic states that are constructed by imposing suitable density constraints on the system. Refined reaction energy profiles are then recovered by performing a configuration interaction (CDFT-CI) calculation within the basis spanned by the diabatic states. After a careful validation of the proposed method, we examined HER catalysis on open-ended carbon nanotubes and discovered that CDFT-CI increased activation energies and decreased reaction energies relative to DFT predictions. We believe that a similar approach could also be adopted to treat overdelocalization effects in other electrocatalytic proton-coupled electron transfer reactions, e.g., in the oxygen reduction reaction.
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Affiliation(s)
- Nico Holmberg
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Kari Laasonen
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
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26
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Tuomi S, Pakkanen OJ, Borghei M, Kronberg R, Sainio J, Kauppinen EI, Nasibulin AG, Laasonen K, Kallio T. Experimental and Computational Investigation of Hydrogen Evolution Reaction Mechanism on Nitrogen Functionalized Carbon Nanotubes. ChemCatChem 2018. [DOI: 10.1002/cctc.201800479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Sami Tuomi
- Research Group of Electrochemical Energy Conversion and Storage Department of Chemistry and Material Science; Aalto University; P.O. Box 16100 Aalto 00076 Finland
| | - Olli J. Pakkanen
- Research Group of Computational Chemistry Department of Chemistry and Material Science; Aalto University; P.O. Box 16100 Aalto 00076 Finland
| | - Maryam Borghei
- Bio-based Colloids and Materials Department of Bioproducts and Biosystems; Aalto University; P.O. Box 16300 Aalto 00076 Finland
- Department of Applied Physics School of Science; Aalto University; P.O. Box 15100 Aalto 00076 Finland
| | - Rasmus Kronberg
- Research Group of Electrochemical Energy Conversion and Storage Department of Chemistry and Material Science; Aalto University; P.O. Box 16100 Aalto 00076 Finland
| | - Jani Sainio
- Surface Science Group Department of Applied Physics; Aalto University; P.O. Box 15100 Aalto 00076 Finland
| | - Esko I. Kauppinen
- Department of Applied Physics School of Science; Aalto University; P.O. Box 15100 Aalto 00076 Finland
| | - Albert G. Nasibulin
- Department of Applied Physics School of Science; Aalto University; P.O. Box 15100 Aalto 00076 Finland
- Skolkovo Institute of Science and Technology; 100 Novaya str. Skolkovo 143025 Russia
| | - Kari Laasonen
- Research Group of Computational Chemistry Department of Chemistry and Material Science; Aalto University; P.O. Box 16100 Aalto 00076 Finland
| | - Tanja Kallio
- Research Group of Electrochemical Energy Conversion and Storage Department of Chemistry and Material Science; Aalto University; P.O. Box 16100 Aalto 00076 Finland
- “MISiS” Department of Functional Nanosystems and High-Temperature Materials; National University of Science and Technology; Leninsky Avenue 4 Moscow 119049 Russia
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27
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Partanen L, Murdachaew G, Laasonen K. Oxygen Evolution Reaction Kinetic Barriers on Nitrogen-Doped Carbon Nanotubes. J Phys Chem C Nanomater Interfaces 2018; 122:12892-12899. [PMID: 30405870 PMCID: PMC6203181 DOI: 10.1021/acs.jpcc.8b03269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/21/2018] [Indexed: 05/17/2023]
Abstract
We investigate kinetic barriers for the oxygen evolution reaction (OER) on singly and doubly nitrogen-doped single-walled carbon nanotubes (NCNTs) using the climbing image nudged elastic band method with solvent effects represented by a 45-water-molecule droplet. The studied sites were chosen based on a previous study of the same systems utilizing a thermodynamic model which ignored both solvent effects and kinetic barriers. According to that model, the two studied sites, one on a singly nitrogen-doped CNT and the other on a doubly doped CNT, were approximately equally suitable for OER. For the four-step OER process, however, our reaction barrier calculations showed a clear difference in the rate-determining *OOH formation step between the two systems, with barrier heights differing by more than 0.4 eV. Thus, the simple thermodynamic model may alone be insufficient for identifying optimal OER sites. Of the remaining three reaction steps, the two H2O forming ones were found to be barrierless in all cases. We also performed solvent-free barrier calculations on NCNTs and undoped CNTs. Substantial differences were observed in the energies of the intermediates when the solvent was present. In general, the observed low activation energy barriers for these reactions corroborate both experimental and theoretical findings of the utility of NCNTs for OER catalysis.
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28
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Weckman T, Laasonen K. Atomic Layer Deposition of Zinc Oxide: Study on the Water Pulse Reactions from First-Principles. J Phys Chem C Nanomater Interfaces 2018; 122:7685-7694. [PMID: 30405869 PMCID: PMC6203180 DOI: 10.1021/acs.jpcc.7b11469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/19/2018] [Indexed: 06/08/2023]
Abstract
Atomic layer deposition (ALD) of zinc oxide thin films has been under intense research in the past few years. The most common precursors used in this process are diethyl zinc (DEZ) and water. The surface chemistry related to the growth of a zinc oxide thin film via atomic layer deposition is not entirely clear, and the ideal model of the process has been contradicted by experimental data, e.g., the incomplete elimination of the ethyl ligands from the surface and the non-negative mass change during the water pulse. In this work we investigate the surface reactions of water during the atomic layer deposition of zinc oxide. The adsorption and ligand-exchange reactions of water are studied on ethyl-saturated surface structures to grasp the relevant surface chemistry contributing to the deposition process. The complex ethyl-saturated surface structures are adopted from a previous publication on the DEZ/H2O-process, and different configurations are sampled using ab initio molecular dynamics in order to find a suitable minimum structure. Water molecules are found to adsorb exothermically onto the ethyl-covered surface at all the ethyl concentrations considered. We do not observe an adsorption barrier for water at 0 K; however, the adsorption energy for any additional water molecules decreases rapidly at high ethyl concentrations. Ligand-exchange reactions are studied at various surface ethyl coverages. The water pulse ligand-exchange reactions have overall larger activation energies than surface reactions for diethyl zinc pulse. For some of the configurations considered, the reaction barriers may be inaccessible at the process conditions, suggesting that some ligands may be inert toward ligand-exchange with water. The activation energies for the surface reactions show only a weak dependence on the surface ethyl concentration. The sensitivity of the adsorption of water at high ethyl coverages suggests that at high ligand-coverages the kinetics may be somewhat hindered due to steric effects. Calculations on the ethyl-covered surfaces are compared to a simple model containing a single monoethyl zinc group. The calculated activation energy for this model is in line with calculations done on the complex model, but the adsorption of water is poorly described. The weak adsorption bond onto a single monoethyl zinc is probably due to a cooperative effect between the surface zinc atoms. A cooperative effect between water molecules is also observed; however, the effect on the activation energies is not as significant as has been reported for other ALD processes.
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Affiliation(s)
- Timo Weckman
- Department of Chemistry and
Materials Science, School of Chemical Engineering, Aalto University, Espoo 00076, Finland
| | - Kari Laasonen
- Department of Chemistry and
Materials Science, School of Chemical Engineering, Aalto University, Espoo 00076, Finland
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29
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Abstract
Nanoparticles of nickel phosphide are promising materials to replace the currently used rare Pt-group metals at cathode-side electrodes in devices for electrochemical hydrogen production.
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Affiliation(s)
- Mikko Hakala
- Department of Chemistry and Materials Science
- Aalto University
- FI-00076 Aalto
- Finland
| | - Kari Laasonen
- Department of Chemistry and Materials Science
- Aalto University
- FI-00076 Aalto
- Finland
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30
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Abstract
DFT calculations showed possible hydrocarbon chain growth on Fe55@C240 preferentially via a CO insertion mechanism.
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Affiliation(s)
- Geraldine Cilpa-Karhu
- Department of Chemistry and Materials Science
- Aalto University
- COMP centre of Excellence in computational Nanoscience
- FI-OOO76 Aalto
- Finland
| | - Kari Laasonen
- Department of Chemistry and Materials Science
- Aalto University
- COMP centre of Excellence in computational Nanoscience
- FI-OOO76 Aalto
- Finland
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31
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Tavakkoli M, Nosek M, Sainio J, Davodi F, Kallio T, Joensuu PM, Laasonen K. Functionalized Carbon Nanotubes with Ni(II) Bipyridine Complexes as Efficient Catalysts for the Alkaline Oxygen Evolution Reaction. ACS Catal 2017. [DOI: 10.1021/acscatal.7b02878] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohammad Tavakkoli
- Physical
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Magdalena Nosek
- Organic
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Jani Sainio
- Department
of Applied Physics, School of Science, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland
| | - Fatemeh Davodi
- Physical
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Tanja Kallio
- Physical
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Pekka M Joensuu
- Organic
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- Physical
Chemistry Group, Department of Chemistry and Material Sciences, School
of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
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32
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Tavakkoli M, Holmberg N, Kronberg R, Jiang H, Sainio J, Kauppinen EI, Kallio T, Laasonen K. Electrochemical Activation of Single-Walled Carbon Nanotubes with Pseudo-Atomic-Scale Platinum for the Hydrogen Evolution Reaction. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00199] [Citation(s) in RCA: 229] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mohammad Tavakkoli
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Nico Holmberg
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Rasmus Kronberg
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Hua Jiang
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Jani Sainio
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Esko I. Kauppinen
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Tanja Kallio
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
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33
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Holmberg N, Laasonen K. Efficient Constrained Density Functional Theory Implementation for Simulation of Condensed Phase Electron Transfer Reactions. J Chem Theory Comput 2017; 13:587-601. [PMID: 28009515 DOI: 10.1021/acs.jctc.6b01085] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Constrained density functional theory (CDFT) is a versatile tool for probing the kinetics of electron transfer (ET) reactions. In this work, we present a well-scaling parallel CDFT implementation relying on a mixed basis set of Gaussian functions and plane waves, which has been specifically tailored to investigate condensed phase ET reactions using an explicit, quantum chemical representation of the solvent. The accuracy of our implementation is validated against previous theoretical results for predicting electronic couplings and charge transfer energies. Subsequently, we demonstrate the efficiency of our method by studying the intramolecular ET reaction of an organic mixed-valence compound in water using a CDFT based molecular dynamics simulation.
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Affiliation(s)
- Nico Holmberg
- COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland
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34
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Kronberg R, Hakala M, Holmberg N, Laasonen K. Hydrogen adsorption on MoS2-surfaces: a DFT study on preferential sites and the effect of sulfur and hydrogen coverage. Phys Chem Chem Phys 2017; 19:16231-16241. [DOI: 10.1039/c7cp03068a] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
H-Adsorption on MoS2-surfaces is studied as a function of structural parameters and an assessment of the intricate structure–property relations is conducted.
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Affiliation(s)
- Rasmus Kronberg
- Research Group of Computational Chemistry
- Department of Chemistry and Materials Science
- Aalto University
- P.O. Box 16100
- FI-00076 Aalto
| | - Mikko Hakala
- Research Group of Computational Chemistry
- Department of Chemistry and Materials Science
- Aalto University
- P.O. Box 16100
- FI-00076 Aalto
| | - Nico Holmberg
- Research Group of Computational Chemistry
- Department of Chemistry and Materials Science
- Aalto University
- P.O. Box 16100
- FI-00076 Aalto
| | - Kari Laasonen
- Research Group of Computational Chemistry
- Department of Chemistry and Materials Science
- Aalto University
- P.O. Box 16100
- FI-00076 Aalto
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35
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Lanzani G, Seitsonen AP, Iannuzzi M, Laasonen K, Pehkonen SO. Isomerism of Trimeric Aluminum Complexes in Aqueous Environments: Exploration via DFT-Based Metadynamics Simulation. J Phys Chem B 2016; 120:11800-11809. [PMID: 27766881 DOI: 10.1021/acs.jpcb.6b08112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chemistry of aluminum or oxo-aluminum in water is still relatively unknown, although it is the basis for many chemical and industrial processes, including flocculation in water treatment plants. Trimeric species have a predominant role in the formation of the Keggin cations, which are the basic building blocks of aluminum-based chemicals. Despite this, details of the structural evolution of these small solvated clusters and how this is related to the processes leading to the formation of larger aggregates are still an open issue. To address these questions, here, we have applied the metadynamics (MTD) simulation technique [ Barducci , A. ; Wiley Interdiscip. Rev.: Comput. Mol. Sci. 2010 , 1 , 826 - 843 ] with density functional theory-based molecular dynamics to disclose the dynamics and structural conversions of trimeric aluminum complexes in an aqueous environment. The existence of a variety of competing metastable conformations, for example, book-like, cyclic boat, and linear shape conformations, is revealed in the MTD simulation. Furthermore, equilibrium simulations of the various intermediate states encountered along the MTD trajectory are used to assess their (meta)stability, determine the rearrangement of the OH ligands, and discuss the role of the solvating water.
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Affiliation(s)
- Giorgio Lanzani
- Thule-Institute, University of Oulu , P.O. Box 7300, FI-90014 University of Oulu, Finland
| | - Ari P Seitsonen
- Institut für Chemie, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.,Département de Chimie, École Normale Supérieure , 24 rue Lhomond, F-75005 Paris, France
| | - Marcella Iannuzzi
- Institut für Chemie, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Kari Laasonen
- Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland
| | - Simo O Pehkonen
- Department of Environmental and Biosciences, University of Eastern Finland , PL 1627, FI-70211 Kuopio, Finland
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36
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Ma L, Melander M, Weckman T, Lipasti S, Laasonen K, Akola J. DFT simulations and microkinetic modelling of 1-pentyne hydrogenation on Cu20 model catalysts. J Mol Graph Model 2016; 65:61-70. [PMID: 26930446 DOI: 10.1016/j.jmgm.2016.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 10/22/2022]
Abstract
Adsorption and dissociation of H2 and hydrogenation of 1-pentyne on neutral and anionic Cu20 clusters have been investigated using the density functional theory and microkinetic modelling. Molecular adsorption of H2 is found to occur strictly at atop sites. The H2 dimer is activated upon adsorption, and the dissociation occurs with moderate energy barriers. The dissociated H atoms reside preferentially on 3-fold face and 2-fold edge sites. Based on these results, the reaction paths leading to the partial and total hydrogenation of 1-pentyne have been studied step-by-step. The results suggest that copper clusters can display selective activity on the hydrogenation of alkyne and alkene molecules. The hydrogenated products are more stable than the corresponding initial reactants following an energetic staircase with the number of added H atoms. Stable semi-hydrogenated intermediates are formed before the partial (1-pentene) and total (pentane) hydrogenation stages of 1-pentyne. The microkinetic model analysis shows that C5H10 is the dominant product. Increasing the reactants (C5H8/H2) ratio enhances the formation of products (C5H10 and C5H12).
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Affiliation(s)
- Li Ma
- COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland; Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
| | - Marko Melander
- COMP Centre of Excellence, Department of Chemistry, Aalto University, FI-00076 Aalto, Finland
| | - Timo Weckman
- COMP Centre of Excellence, Department of Chemistry, Aalto University, FI-00076 Aalto, Finland
| | - Saana Lipasti
- COMP Centre of Excellence, Department of Chemistry, Aalto University, FI-00076 Aalto, Finland
| | - Kari Laasonen
- COMP Centre of Excellence, Department of Chemistry, Aalto University, FI-00076 Aalto, Finland
| | - Jaakko Akola
- COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland; Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland.
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37
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Srivastava D, Laasonen K. Dissociative adsorption of O2 on negatively charged nitrogen-doped single-walled carbon nanotubes: first-principles calculations. RSC Adv 2016. [DOI: 10.1039/c6ra14023h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Spin unrestricted DFT calculations have been used to study the molecular and dissociative adsorption of O2 on achiral substitutional nitrogen-doped single-walled carbon nanotubes with and without additional charges.
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Affiliation(s)
| | - Kari Laasonen
- Department of Chemistry
- Aalto University
- 00076 Aalto
- Finland
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38
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Abstract
Fermi level equilibration driven charge redistribution and electric dipole formation was quantified using a simple nanocapacitor model for bimetallic nanoparticles.
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Affiliation(s)
- Nico Holmberg
- COMP Centre of Excellence in Computational Nanoscience
- Department of Chemistry
- Aalto University
- FI-00076 Aalto
- Finland
| | - Kari Laasonen
- COMP Centre of Excellence in Computational Nanoscience
- Department of Chemistry
- Aalto University
- FI-00076 Aalto
- Finland
| | - Pekka Peljo
- Laboratoire d'Electrochimie Physique et Analytique
- École Polytechnique Fédérale de Lausanne
- EPFL Valais Wallis
- CH-1951 Sion
- Switzerland
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39
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Abstract
Carbon nanotubes (CNTs), while inactive by themselves, are often used as a platform in the search of new catalysts for the hydrogen evolution reaction (HER) by introducing metal nanoparticles or other dopants. Here, we examine the HER activity of pristine open-ended CNTs considering both the effects of chirality and hydrogen coverage using electronic structure calculations. The results indicate that the formation of different 5-ring structures at the end of the CNT introduces surface sites that are highly active toward HER, whereas the activity of traditional 6-ring sites is not greatly altered by tube termination. At fixed hydrogen coverage, the enhanced activity of these sites was attributed to valence orbitals residing close to the highest occupied molecular level facilitating electron transfer to protons.
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Affiliation(s)
- Nico Holmberg
- COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland
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40
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Abstract
Atomic layer deposition (ALD) is a coating technology used to produce highly uniform thin films. Aluminiumoxide, Al2O3, is mainly deposited using trimethylaluminium (TMA) and water as precursors and is the most studied ALD-process to date. However, only few theoretical studies have been reported in the literature. The surface reaction mechanisms and energetics previously reported focus on a gibbsite-like surface model but a more realistic description of the surface can be achieved when the hydroxylation of the surface is taken into account using dissociatively adsorbed water molecules. The adsorbed water changes the structure of the surface and reaction energetics change considerably when compared to previously studied surface model. Here we have studied the TMA-H2O process using density functional theory on a hydroxylated alumina surface and reproduced the previous results for comparison. Mechanisms and energetics during both the TMA and the subsequent water pulse are presented. TMA is found to adsorb exothermically onto the surface. The reaction barriers for the ligand-exchange reactions between the TMA and the surface hydroxyl groups were found to be much lower compared to previously presented results. TMA dissociation on the surface is predicted to saturate at monomethylaluminium. Barriers for proton diffusion between surface sites are observed to be low. TMA adsorption was also found to be cooperative with the formation of methyl bridges between the adsorbants. The water pulse was studied using single water molecules reacting with the DMA and MMA surface species. Barriers for these reactions were found to reasonable in the process conditions. However, stabilizing interactions amongst water molecules were found to lower the reaction barriers and the dynamical nature of water is predicted to be of importance. It is expected that these calculations can only set an upper limit for the barriers during the water pulse.
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Affiliation(s)
- Timo Weckman
- Aalto University, Kemistintie 1, Espoo, Finland.
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41
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Abstract
The improvement of charge transfer between an organic molecule and a semiconductor is an important and challenging goal in the fields of photovoltaics and photocatalysis. In this work, we present a time-dependent density functional theory investigation of the impact of Ga-V codoping of TiO2 on the excited-state electron injection from perylene-3-carboxylic acid. The doping is shown to raise the charge-transfer efficiency for the highest possible surface dye uptake by ∼16%. The strength of the effect depends on the dopant-pair-dye separation, dopant concentration, and distribution of Ga, V atoms in TiO2. The doping of the superficial level turns out to be more favorable than those in the bulk. The changes in electron injection dynamics are attributed to the modification of accepting semiconductor levels and hybridization profile between molecular and semiconductor states.
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Affiliation(s)
- Olga A Syzgantseva
- †COMP, Department of Chemistry, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- ‡COMP, Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto, Finland
| | - Martti Puska
- ‡COMP, Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- †COMP, Department of Chemistry, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
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42
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Ma L, Melander M, Laasonen K, Akola J. CO oxidation catalyzed by neutral and anionic Cu20 clusters: relationship between charge and activity. Phys Chem Chem Phys 2015; 17:7067-76. [PMID: 25687378 DOI: 10.1039/c5cp00365b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of CO and O2 on neutral and anionic Cu20 clusters have been investigated by spin-polarized density functional theory. Three reaction mechanisms of CO oxidation are explored: reactions with atomic oxygen (dissociated O2) as well as reactions with molecular oxygen, including Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. The adsorption energies, reaction pathways, and reaction barriers for CO oxidation are calculated systematically. The anionic Cu20(-) cluster can adsorb CO and O2 more strongly than the neutral counterpart due to the superatomic shell closing of 20 valence electrons which leaves one electron above the band gap. The activation of O2 molecule upon adsorption is crucial to determine the rate of CO oxidation. The CO oxidation proceeds efficiently on both Cu20 and Cu20(-) clusters, when O2 is pre-adsorbed dissociatively. The ER mechanism has a lower reaction barrier than the LH mechanism on the neutral Cu20. In general, CO oxidation occurs more readily on the anionic Cu20(-) (effective reaction barriers 0.1-0.3 eV) than on the neutral Cu20 cluster (0.3-0.5 eV). Moreover, Cu20(-) exhibits enhanced binding for CO2. From the analysis of the reverse direction of CO oxidation, it is observed that the transition of CO2 to CO + O can occur on the Cu20(-) cluster, which demonstrates that Cu clusters may serve as good catalyst for CO2 chemistry.
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Affiliation(s)
- Li Ma
- COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
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43
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Melander M, Laasonen K, Jónsson H. Removing External Degrees of Freedom from Transition-State Search Methods using Quaternions. J Chem Theory Comput 2015; 11:1055-62. [DOI: 10.1021/ct501155k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Hannes Jónsson
- Faculty
of Physical Sciences, University of Iceland, 107 Reykjavík, Iceland
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44
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Tavakkoli M, Kallio T, Reynaud O, Nasibulin AG, Johans C, Sainio J, Jiang H, Kauppinen EI, Laasonen K. Single-Shell Carbon-Encapsulated Iron Nanoparticles: Synthesis and High Electrocatalytic Activity for Hydrogen Evolution Reaction. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201411450] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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45
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Tavakkoli M, Kallio T, Reynaud O, Nasibulin AG, Johans C, Sainio J, Jiang H, Kauppinen EI, Laasonen K. Single-Shell Carbon-Encapsulated Iron Nanoparticles: Synthesis and High Electrocatalytic Activity for Hydrogen Evolution Reaction. Angew Chem Int Ed Engl 2015; 54:4535-8. [DOI: 10.1002/anie.201411450] [Citation(s) in RCA: 245] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Indexed: 01/28/2023]
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46
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Chen JC, Reischl B, Spijker P, Holmberg N, Laasonen K, Foster AS. Ab initio Kinetic Monte Carlo simulations of dissolution at the NaCl-water interface. Phys Chem Chem Phys 2014; 16:22545-54. [PMID: 25227553 DOI: 10.1039/c4cp02375g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have used ab initio molecular dynamics (AIMD) simulations to study the interaction of water with the NaCl surface. As expected, we find that water forms several ordered hydration layers, with the first hydration layer having water molecules aligned so that oxygen atoms are on average situated above Na sites. In an attempt to understand the dissolution of NaCl in water, we have then combined AIMD with constrained barrier searches, to calculate the dissolution energetics of Na(+) and Cl(-) ions from terraces, steps, corners and kinks of the (100) surface. We find that the barrier heights show a systematic reduction from the most stable flat terrace sites, through steps to the smallest barriers for corner and kink sites. Generally, the barriers for removal of Na(+) ions are slightly lower than for Cl(-) ions. Finally, we use our calculated barriers in a Kinetic Monte Carlo as a first order model of the dissolution process.
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Affiliation(s)
- Jian-Cheng Chen
- COMP Centre of Excellence and Department of Applied Physics, Aalto University, FI-00076 Helsinki, Finland.
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47
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Holmberg N, Sammalkorpi M, Laasonen K. Ion Transport through a Water–Organic Solvent Liquid–Liquid Interface: A Simulation Study. J Phys Chem B 2014; 118:5957-70. [DOI: 10.1021/jp412162c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Nico Holmberg
- Department
of Chemistry, Aalto University, Aalto, Finland
| | | | - Kari Laasonen
- Department
of Chemistry, Aalto University, Aalto, Finland
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48
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Abstract
The structure and magnetic moment distribution are studied for an iron nanoparticle with varying degree of carbon adatom coverage. The limiting models of the study are the clean icosahedral Fe55 particle and the iron particle completely enclosed in carbon cages. Between the two extrema, partially covered particles are considered. The iron cluster with partial coverage of carbon adatoms represents a model of active catalysts in the chemical vapor deposition synthesis of carbon nanotubes. The investigated structures are the bare Fe55 cluster, Fe55N4C(x) (x = 27, 37, 47, 54, 65), and Fe55 encapsulated inside C180 and C240. The two latter are extreme examples of an iron particle completely enclosed in a carbon network. Fe55@C180 and Fe55@C240 present novel structures resembling the endohedral metallofullerenes. Two structural isomers of the Fe55@C180 are considered. Enclosing the Fe55 cluster inside C180 and C240 fullerenes gives rise to changes in the Fe-Fe bond lengths. This alters the magnetic structure of the iron cluster considerably. The interaction between the fullerenes and the enclosed iron cluster is reflected in a charge transfer of 8-13 electrons in the considered endohedral complexes. The localization of atomic charges on the C180 and C240 cages suggests site-selective reactivity of the endohedral complexes. The total magnetic moments of the Fe55N4C(x) nanoparticles vary with the degree of adatom coverage. The magnetic moments of individual Fe atoms depend strongly on the element of the nearest-neighbor atoms and on the coordination number and carry therefore information about the local chemistry.
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Affiliation(s)
- Stefan Taubert
- Department of Chemistry, Aalto University School of Chemical Technology, FI-00076 Aalto, Finland.
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49
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Abstract
NaCl nanocrystal dissolution was investigated in atomistic detail revealing a difference in the solvation of two different ionic species.
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Affiliation(s)
- Nico Holmberg
- Department of Chemistry
- Aalto University
- FI-00076 Aalto, Finland
| | - Jian-Cheng Chen
- Department of Applied Physics
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
| | - Adam S. Foster
- Department of Applied Physics
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
| | - Kari Laasonen
- Department of Chemistry
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
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50
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Mace A, Laasonen K, Laaksonen A. Free energy barriers for CO2and N2in zeolite NaKA: an ab initio molecular dynamics approach. Phys Chem Chem Phys 2014; 16:166-72. [DOI: 10.1039/c3cp52821a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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