Ion Interactions with Carbon Nanomaterial Surfaces in Aqueous and Non-aqueous Solutions [Elektronische Ressource] / Andrey Frolov. Gutachter: Maxim Fedorov ; Eckhard Spohr

Frolov

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• Publié par: universitat_duisburg-essen
• Publié le: 01 janvier 2011
• Nombre de lectures: 21
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

IonInteractionswithCarbonNanomaterial
SurfacesinAqueousandNon-aqueousSolutions
Dissertation
zurErlangungdesakademischenGradeseines
DoktorsderNaturwissenschaften
–Dr. rer. nat. –
vorgelegt von
AndreyI.Frolov
geboreninIvanovo,USSR
FakultätfürChemie
der
UniversitätDuisburg-Essen
2011DievorliegendeArbeitwurdeimZeitraumvonJuli2008bisJuni2011imArbeitskreisvon
PhD,DSc,Priv.-Doz. MaximV.FedorovamMax-Planck-InstitutfürMathematikindenNatur-
wissenschaften,Leipzig,durchgeführt.
TagderDisputation: 20.09.2011
Gutachter: PhD,DSc,Priv.-Doz. MaximV.Fedorov
Prof. Dr. EckhardSpohr
Vorsitzender: Prof. Dr. ThomasSchraderCONTENTS 3
Contents
1 Introduction 9
1.1 Salteffectsatsolvationinterfaces . . ....................... 9
1.2 Carbonnanomaterials ............................... 9
1.3 Importanceofcarbonnanomaterialdispersions . . ............... 11
1.3.1 Aqueousdispersions ........................... 12
1.3.2 Organicsolventdispersions . 12
1.3.3 IonicLiquiddispersions . . ....................... 13
1.4 Ioneffectsoncarbonnanomaterialdispersionproperties . . . . ........ 14
2 Theoreticalbackground 17
2.1 Molecularparametersandfunctionsdescribingionicsolutions . ........ 17
2.1.1 RadialDistributionFunction ....................... 17
2.1.2 PairCorrelationFunction . . . 17
2.1.3 PotentialofMeanForce . . . 18
2.1.4 Solvation/Hydrationshell . . 20
2.1.5 Coordinationnumber ........................... 21
2.1.6 Residencetime .............................. 22
2.1.7 Samoilov’senergy . . 23
2.1.8 Positiveandnegativehydration . . ................... 24
2.1.9 SolvationFreeEnergy .......................... 24
2.2 Asymmetryofionhydration . 24
2.2.1 Chargeoverscreening . 24
2.2.2 Ionhydrationthermodynamics...................... 25
2.3 Iondirectcontactformationinsolution 27
2.3.1 Generalscheme.............................. 27
2.3.2 Collinspyramid: the"lawofmatchingwateraffinities" . ........ 28
3 Modellingapproach 31
3.1 MolecularDynamicssimulation......................... 31
3.2 Integrationschemes................................ 32
3.2.1 Verletintegrator . . ........................... 32
3.3 Forcecalculation................................. 33
3.4 Periodicboundarycondition . 35CONTENTS 4
3.5 Short-rangeinteractions(Celllists) . ....................... 37
3.6 Long-range.............................. 38
3.7 Ewaldsummationmethod............................ 38
3.7.1 RealspaceEwaldsum .......................... 40
3.7.2 ReciprocalspaceEwaldsum ....................... 42
3.7.3 Ewaldsummationsummary . 43
3.8 MeshEwaldmethods . 44
4 Resultsanddiscussion 46
4.1 Ioninteractionwiththecarbonnanotubesurfaceinaqueoussolutions . . . . . 46
4.1.1 SimulationMethods ........................... 46
4.1.2 Thecarbonnanotubehydrationshell ................... 51
4.1.3 Iondistributionsaroundthecarbonnanotube .............. 53
4.1.4 Ion-carbonnanotubeinterfaceshellcriteria . 54
4.1.5 Partialdehydrationofionsatthecarbonnanotubesurface ....... 57
4.1.6 Measureofthepenaltyforpartialdehydration.............. 61
4.1.7 Ionsconcentrationinthecarbonnanotube-ioninterfaceshell . . . . . . 64
4.1.8 Ionsresidencetimesatthecarbonnanotube-waterinterface . . . . . . 64
4.1.9 Discussionofthesimulationresultsinlightofexperimentaldata . . . . 66
4.1.10 Conclusions . ............................... 67
4.2 IoninteractionwiththecarbonnanotubesurfaceinN-methyl-2-pyrrolidonedis-
persions...................................... 68
4.2.1 Simulationdetails . ........................... 68
4.2.2 IonsolvationinthebulkNaI–N-methyl-2-pyrrolidonesolution . . . . 70
4.2.3 IonsbehavioratthecarbonnanotubesurfaceinN-methyl-2-pyrrolidone
dispersion................................. 72
4.2.4 Comparisontoaqueoussolutions . ................... 74
4.2.5 Thermodynamicsofiondepletionatthecarbonnanotubesurface . . . 75
4.2.6 Discussionofthesimulationresultsinlightofexperimentaldata . . . . 80
4.2.7 Conclusions . ............................... 83
4.3 Interaction of molecular ions with the carbon "nanoonion" surface in organic
salt/acetonitrilesolutions . . ........................... 85
4.3.1 Simulationdetails . . 86
4.3.2 Structureofthecarbon"nanoonion"interfaceshell . . . ........ 88CONTENTS 5
4.3.3 Conclusions . ............................... 91
4.4 Interactionofmolecularionswiththecarbonnanotubesurfaceinroomtemper-
atureionicliquids/acetonitrilemixtures . . ................... 92
4.4.1 Simulationdetails . ........................... 92
4.4.2 Neutralcarbonnanotubesurface . . . 95
4.4.3 Changesintheinterfacialstructuresinresponsetotheexternal field . . 97
4.4.4 Effectsofacetonitrilesolventontheelectricdoublelayer ........ 99
4.4.5 Molecularionorientationsatthecarbonnanotubesurface100
4.4.6 Effects of the length of the cation alkyl chain on the structure of the
electricaldoublelayer ..........................108
4.4.7 Correlationswiththeexperimentaldata . . ...............110
4.4.8 Conclusions . ...............................111
5 Summary 113
6 Literature 118
7 Appendix 137
7.1 ListofAbbreviations ...............................137
7.2 Shortsummary ..................................140
7.3 ListofPublications................................141
7.4 CurriculumVitae(CV)144
7.5 Erkärung . . .148
7.6 Acknowledgements149LISTOFFIGURES 6
ListofFigures
1 Carbonnanomaterials ............................... 10
2 Carbonnanotubechirality . . ........................... 11
3Definitionofthesolvationshells . . ....................... 18
4 Activation free energy of solvent molecules release from the solvation shell of
anion....................................... 22
5 Asymmetryofionhydration . 25
6ofionhydration: theiondehydrationfreeenergies . ........ 26
7 Asymmetryofion theentropyterm.................. 26
8 Mechanismoftheiondirectcontactformation 28
9 Collinspyramid.................................. 29
10 Molecularinteractionsinmoleculardynamicssimulations . . . ........ 33
11 Periodicboundaryconditions ........................... 36
12 Intermolecularinteractionwiththeperiodicboundaryconditions ........ 37
13 Ewaldsummationmethod: infinitelatticerepresentation . . . . . 39
14 Ewaldmethod: decompositionofthechargedensity ........ 40
15 Anexamplesimulationboxofalkalihalideaqueoussolutionwithcarbonnanotube 47
16 Normalizationofradialdensityprofiles..................... 51
17 Waterdistributionaroundcarbonnanotube . ................... 52
18 Thewateroxygenandhydrogenradialdensityprofilesaroundcarbonnanotube 53
19 Iondistributionaroundcarbonnanotubeinaqueoussolutions . . ........ 54
20 Ion-carbonnanotubeinterfaceshell . ....................... 55
21 Radialdensityprofilesofionsaroundcarbonnanotubeinaqueousdispersions . 56
22 Ionhydrationnumberasafunctionofdistancefromcarbonnanotube . . . . . 58
23 Reductionoftheionhydrationnumberatthecarbonnanotubesurface . . . . . 60
24 Ionhydrationnumberasafunctionofionicradii . ............... 60
25 Ion-waterpotentialsofmeanforce . ....................... 61
26 Comparisonoftheion-waterandwater-waterpotentialsofmeanforce . . . . . 62
27 Ionconcentrationatthecarbonnanotubesurface . ............... 65
28 Ionresidencetimeatthecarbonnanotubesurface . . 66
29 Ion–N-methyl-2-pyrrolidoneradialdistributionfunctions . . . ........ 71
30 Ionsolvationnumbersasafunctionofdistancefromthecarbonnanotube . . . 72LISTOFFIGURES 7
31 Radial density profiles of ions and N-methyl-2-pyrrolidone molecules around
thecarbonnanotube . ............................... 73
32 RadialdensityprofilesofwaterandN-methyl-2-pyrrolidone . . ........ 76
33 Thecalculatedpreferentialinteractioncoefficientofions............ 78
34 PhtoluminescenceofthecarbonnanotubedispersedinN-methyl-2-pyrrolidone 81
35 PhotographsofthesamplescontainingtheCNT-NMPdispersions ....... 81
36 AbsorbancespectraofthecarbonnanotubesdispersedinN-methyl-2-pyrrolidone 82
37 Electrolytesforthecarbon"nanoonion"simulations ............... 86
38 Examplesimulationboxwithamodelcarbon"nanoonion" . . . ........ 87
39 Radialdensitydistributionofspeciesaroundthecarbon"nanoonion" . . . . . . 89
40 Distributionofparticlesinbulksolutionsoforganicsaltinacetonitrile . . . . . 90
41 Representationofmolecularspecies....................... 93
42 RadialdensityprofilesofEMImandTFSImolecularions............ 95
43 Orientationofmolecularionsaroundcarbonnanotube. Criteria . ........ 96
44 Radialdensityprofilesofmolecularions..................... 98
45 Radialdensityprofilesofacetonitrilearoundcarbonnanotube . ........ 98
46 Orientationprobabilitydensityasthefunctionofdistance. Explanation . . . . 101
47 Average number of molecular ions oriented parallel and perpendicular to the
carbonnanotubesurface . . ...........................107
48 Orientationofmolecularionsaroundcarbonnanotube . . . . . ........109LISTOFTABLES 8
ListofTables
1 Listofpotentialparameters............................ 48
2 Carbonnanotube-ioninterfaceshellboundaries . . ............... 57
3 Hydrationnumbersofions . ........................... 59
4 Freeenergiesofonewatermoleculereleasefromtheionhydrationshell . . . . 63
5 Numbersofthemolecularspeciesinthesimulationboxes............ 94
6 Volumesofsolutecavitiesinacetonitrile . . ................... 99