Physical Electrochemistry: Fundamentals, Techniques, and Applications

481 Pages·2018·13.616 MB·English

by  Noam Eliaz, Eliezer Gileadi

PhysicalElectrochemistry

Physical Electrochemistry
Fundamentals,Techniques,andApplications
NoamEliazandEliezerGileadi
SecondEdition
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vii
Contents
Preface xvii
SymbolsandAbbreviations xix
1 Introduction 1
1.1 GeneralConsiderations 1
1.1.1 TheTransitionfromElectronictoIonicConduction 1
1.1.2 TheResistanceoftheInterfacecanbeInfinite 2
1.1.3 Mass-TransportLimitation 2
1.1.4 TheCapacitanceattheMetal/SolutionInterphase 4
1.2 PolarizableandNonpolarizableInterfaces 4
1.2.1 Phenomenology 4
1.2.2 TheEquivalentCircuitRepresentation 5
FurtherReading 7
2 ThePotentialsofPhases 9
2.1 TheDrivingForce 9
2.1.1 DefinitionoftheElectrochemicalPotential 9
2.1.2 SeparabilityoftheChemicalandtheElectricalTerms 10
2.2 TwoCasesofSpecialInterest 11
2.2.1 EquilibriumofaSpeciesBetweentwoPhasesinContact 11
2.2.2 TwoIdenticalPhasesnotatEquilibrium 12
2.3 TheMeaningoftheStandardHydrogenElectrode(SHE)Scale 13
FurtherReading 15
3 FundamentalMeasurementsinElectrochemistry 17
3.1 MeasurementofCurrentandPotential 17
3.1.1 TheCellVoltageistheSumofSeveralPotentialDifferences 17
3.1.2 UseofaNonpolarizableCounterElectrode 17
3.1.3 TheThree-ElectrodeSetup 18
3.1.4 ResidualjR PotentialDropinaThree-ElectrodeCell 18
S
3.2 CellGeometryandtheChoiceoftheReferenceElectrode 19
3.2.1 TypesofReferenceElectrodes 19
3.2.2 UseofanAuxiliaryReferenceElectrodefortheStudyof
FastTransients 20
viii Contents
3.2.3 CalculatingtheUncompensatedSolutionResistancefor
afewSimpleGeometries 21
3.2.3.1 PlanarConfiguration 21
3.2.3.2 CylindricalConfiguration 21
3.2.3.3 SphericalSymmetry 22
3.2.4 PositioningtheReferenceElectrode 22
3.2.5 EdgeEffects 24
FurtherReading 26
4 ElectrodeKinetics:SomeBasicConcepts 27
4.1 RelatingElectrodeKineticstoChemicalKinetics 27
4.1.1 TheRelationofCurrentDensitytoReactionRate 27
4.1.2 TheRelationofPotentialtoEnergyofActivation 28
4.1.3 Mass-TransportLimitationVersusCharge-Transfer
Limitation 30
4.1.4 TheThicknessoftheNernstDiffusionLayer 31
4.2 MethodsofMeasurement 33
4.2.1 PotentialControlVersusCurrentControl 33
4.2.2 TheNeedtoMeasureFastTransients 35
4.2.3 PolarographyandtheDroppingMercuryElectrode(DME) 37
4.3 RotatingElectrodes 40
4.3.1 TheRotatingDiskElectrode(RDE) 40
4.3.2 TheRotatingConeElectrode(RConeE) 44
4.3.3 TheRotatingRingDiskElectrode(RRDE) 45
FurtherReading 47
5 Single-StepElectrodeReactions 49
5.1 TheOverpotential,𝜂 49
5.1.1 DefinitionandPhysicalMeaningofOverpotential 49
5.1.2 TypesofOverpotential 51
5.2 FundamentalEquationsofElectrodeKinetics 52
5.2.1 TheEmpiricalTafelEquation 52
5.2.2 TheTransition-StateTheory 53
5.2.3 TheEquationforaSingle-StepElectrodeReaction 54
5.2.4 LimitingCasesoftheGeneralEquation 56
5.3 TheSymmetryFactor,𝛽,inElectrodeKinetics 59
5.3.1 TheDefinitionof𝛽 59
5.3.2 TheNumericalValueof𝛽 60
5.4 TheMarcusTheoryofChargeTransfer 61
5.4.1 Outer-SphereElectronTransfer 61
5.4.2 TheBorn–OppenheimerApproximation 62
5.4.3 TheCalculatedEnergyofActivation 63
5.4.4 TheValueof𝛽anditsPotentialDependence 64
5.5 Inner-SphereChargeTransfer 65
5.5.1 MetalDeposition 65
FurtherReading 66
Contents ix
6 MultistepElectrodeReactions 67
6.1 MechanisticCriteria 67
6.1.1 TheTransferCoefficient,𝛼,anditsRelationtothe
SymmetryFactor,𝛽 67
6.1.2 SteadyStateandQuasi-Equilibrium 69
6.1.3 CalculationoftheTafelSlope 71
6.1.4 ReactionOrdersinElectrodeKinetics 74
6.1.5 TheEffectofpHonReactionRates 77
6.1.6 TheEnthalpyofActivation 79
FurtherReading 81
7 SpecificExamplesofMultistepElectrodeReactions 83
7.1 ExperimentalConsiderations 83
7.1.1 MultipleProcessesinParallel 83
7.1.2 TheLevelofImpuritythatcanbeTolerated 84
7.2 TheHydrogenEvolutionReaction(HER) 87
7.2.1 HydrogenEvolutiononMercury 87
7.2.2 HydrogenEvolutiononPlatinum 89
7.3 PossiblePathsfortheOxygenEvolutionReaction 91
7.4 TheRoleandStabilityofAdsorbedIntermediates 94
7.5 AdsorptionEnergyandCatalyticActivity 95
FurtherReading 96
8 TheElectricalDoubleLayer(EDL) 97
8.1 ModelsofStructureoftheEDL 97
8.1.1 Phenomenology 97
8.1.2 TheParallel-PlateModelofHelmholtz 99
8.1.3 TheDiffuseDoubleLayerModelofGouyandChapman 100
8.1.4 TheSternModel 103
8.1.5 TheRoleoftheSolventattheInterphase 105
FurtherReading 107
9 Electrocapillary 109
9.1 Thermodynamics 109
9.1.1 AdsorptionandSurfaceExcess 109
9.1.2 TheGibbsAdsorptionIsotherm 111
9.1.3 TheElectrocapillaryEquation 112
9.2 MethodsofMeasurementandSomeResults 114
9.2.1 TheElectrocapillaryElectrometer 114
9.2.2 SomeExperimentalResults 119
9.2.2.1 TheAdsorptionofIons 119
9.2.2.2 AdsorptionofNeutralMolecules 120
FurtherReading 122
10 IntermediatesinElectrodeReactions 123
10.1 AdsorptionIsothermsforIntermediatesFormedby
ChargeTransfer 123