E

Erevdiagnosticsincyclicvoltammetry175●EEE–pHdiagramPourbaixdiagramEadie–HofsteeplotMichaelis–MentenkineticsEastman’sentropyheatoftransportEarthcell—Thiswasabatteryconsistingofacopperandzincelectrodeimmersedinsoil.Itwasusedtopro-duceelectricityfortelegraphing.SeealsoDaniellcell,zinc,Zn+/Znelectrodes,Zn+/Zn(Hg)electrodes,zinc–airbatteries(cell),andLeclanchécell.Ref.:[i]HauckWP()DieGalvanischenBatterien,AccumulatorenundThermosäulen,ndedn.Hartleben’sVerlag,WienFSEarthing—isthefasteningofelectricalequipmenttoearthtomaketheearthapartofanelectricalcircuit(grounding),i.e.,themountingofalow-resistanceelectricallyconductingconnectionbetweenelectricalapparatus,ononeside,andtheearth,ontheother.Thespecificelectricalresistivityof(wet)earthisaboutΩm[i].Earthingisprimarilydonefortheprotec-tionagainstlightningstrikesandelectrostaticdischarges(ESD),viainfluenceorinduction,butalsotoelimi-nateelectricfieldswithinavolumeandtoavoidnoiseincommunicationengineeringdevices.Inthelatter-mentionedbroadermeaning,thisincludesallmeasurestopreventthepick-uportransmissionofstrayelectricalsignals.Seeforthelattershielding.Ref.:[i]WestphalWH(ed)()PhysikalischesWörterbuch.Springer,Berlin,pMHerEbnercell—Thiswasabatteryconsistingofapla-tinizedleadplateandabottomelectrodeofamer-curypoolwithpiecesofzinc.Theelectrolyteisdilutesulfuricacid.SeealsoTyerbattery,Daniellcell,zinc,Zn+/Znelectrodes,Zn+/Zn(Hg)electrodes,zinc–airbatteries(cell),andLeclanchécell.Ref.:[i]HauckWP()DieGalvanischenBatterien,AccumulatorenundThermosäulen,ndedn.Hartleben’sVerlag,WienFSEirrevdiagnosticsincyclicvoltammetry—Forelectro-chemicalsystemswithkineticconstraintsinthehet-erogeneouselectrontransferreaction(irreversibility)thefollowingdiagnosticcriteriacanbeusedincyclicvoltammetry[i–iii]:•forreductionprocesses:Ip,RedIp,Ox;•thehalf-wavepeakpotential(ΔEp)shiftsformVαninnegativedirection(forreductionpro-cesses),perdecadeincreaseofthescanrate(αisthetransfercoefficient);•thepeakcurrentsareproportionaltothesquare-rootofthescanratev.(byredoxreactionscon-trolledbydiffusion);•thepotentialseparationbetweenthecathodicandanodicpeakΔEp=Ep,c−Ep,anmVatC(seeFig.below)anditincreasesbyincreasingthescanrate.Eirrevdiagnosticsincyclicvoltammetry—Figure.SimulatedcyclicvoltammogramforanEirrevreactionRefs.:[i]NicholsonRS,ShainI()AnalChem:;[ii]MarkenF,NeudeckA,BondAM()Cyclicvoltammetry.In:ScholzF(ed)Electroanalyticalmethods.Springer,Berlin,pp–;[iii]BardAJ,FaulknerLR()Electrochemicalmethods.ndedn.Wiley,NewYork,pp–RGErevdiagnosticsincyclicvoltammetry—Foranelectro-chemicallyreversiblereaction(controlledbydiffusion)ofthetypeO+ne−R(seereversibility),thediagnos-ticcriteriaareasfollowsincyclicvoltammetry[i,ii]:•Ip(forboth,reductionandoxidation)isalinearfunctionofthesquare-rootofthescanratev.;•theratioIp,RedIp,Ox=forwiderangeofscanrates;176Ebonexelectrodes●E•thehalf-wavepeakpotential(ΔEp)doesnotchangebyalteringthescanrate;•thepotentialseparationbetweenthecathodicandanodicpeakΔEp=Ep,c−Ep,aisnmVatC(seeFig.below)[i–iii];Erevdiagnosticsincyclicvoltammetry—Figure.SimulatedcyclicvoltammogramforErevreactionRefs.:[i]NicholsonRS,ShainI()AnalChem:;[ii]MarkenF,NeudeckA,BondAM()Cyclicvoltammetry.In:ScholzF(ed)Electroanalyticalmethods.Springer,Berlin,pp–;[iii]BardAJ,FaulknerLR()Electrochemicalmethods.ndedn.Wiley,NewYork,pp–RGEbonexelectrodes—WhenTiOisplacedintoanat-mosphereofhydrogenatatemperaturehigherthanCpartialreductionandformationofTiO−xphasesoccurs.OfparticularinterestisTiO,ablackce-ramicmaterialofhighelectricalconductivityandchem-icalinertness.Thismaterial,Ebonex,hasbeenformedintoceramicelectrodesforapplicationsasdimension-allystableanode[ii]orcathode[iii].Refs.:[i]HayfieldPCS()Developmentofanewmaterial:Mono-lithicTiOebonexceramic.TheRoyalSocietyofChemistry,London;[ii]GravesJE,PletcherD,ClarkeRL,WalshFC()JApplElec-trochem:;[iii]ChenG,BettertonEA,ArnoldRG,ElaWP()JApplElectrochem:FMECprocess—Thisisacasewheretheproduct(R)ofanelectrochemicalreaction(E)reacts(e.g.,withthesol-vent)toproduceaspeciesthatisnotelectroactiveatpo-tentialswheretheredoxprocessoftheelectroactivecou-pleoccurs[i–iii]:Estep:O+ne−RCstep:RB.Theoxidationofascorbicacid,followedbyhydrationoftheproductisonerepresentativeexampleforthistypeofreactions[i]andsubsequentchemicalreactionsinelec-trochemisty.Refs.:[i]NicholsonRS,ShainI()AnalChem:;[ii]MarkenF,NeudeckA,BondAM()Cyclicvoltammetry.In:ScholzF(ed)Electroanalyticalmethods.Springer,Berlin,pp–;[iii]BardAJ,FaulknerL()Electrochemicalmethods.ndedn.Wiley,NewYork,pp–RGECprocess—Thisisaspecialtypeoffollow-upreac-tionoftheproduct(R)oftheelectrochemicalstepwithsomenonelectroactivespecies(Z)insolution,toregen-erateinitialelectroactivesubstrate,O.i.e.:Electrochemicalstep:O+ne−RC(catalytic)step:R+ZO.IftheconcentrationofZismuchlargerthanthatofO,thechemicalreactionispseudofirstorder.Thereduc-tionofTi(IV)inthepresenceofoxalatean