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1、Experimentalclasson“FuelCellandElectrochemistry”ExperimentsetupEquipment:CHI760DelectrochemicalstationThreeelectrodesystem.WE:CE:RE:SaturatedCalomelElectrodeSolution:1.0×10-3mol/LK3[Fe(CN)6]+0.1MKClLabreport1)PlotcurvesofLSVcurve,anddescribewhycurrentchangeswithsweepingvoltage?Reas
2、on:Voltageisadrivingforcetoanelectrodereactions,itisconcernedwiththeequilibriumofelectrontransferatelectrodesurface.Asthealteringofappliedvoltage,theFermi-levelisraised(orlowered),whichchangingtheenergystateoftheelectrons.Makingtheoverallbarrierheight(ieactivationenergy)alterasafun
3、ctionoftheappliedvoltage.(1).Inthisreaction,whenvoltageis0.6V,thereisnoelectrontransfer,sothecurrentiszero.Withthevoltagetothemorereductivevalues,thecurrentincreases.(2).Whenthediffusionlayerhasgrownsufficientlyabovetheelectrodesothatthefluxofreactanttotheelectrodeisnotfastenoughto
4、satisfythatrequiredbyNernstEquation.Thepeakisobtaining.(3).Whenthereactioncontinued,itwouldgetasituationthattherewillbealowerreactantconcentrationattheelectrodethaninbulksolution,thatis,thesupplyoffreshreactanttothesurfacedecreased,socurrentdecreases.1)PlotthecurvesofCVcurveswithdi
5、fferentscanrate;2)FromtheCVcurves,fillthetableScanrate(mV/s)2050100200300400500600Peakcurrent(uA)Ipc8.33613.1718.5025.9631.5436.1740.2343.95Ipa-8.263-13.01-18.19-25.26-30.50-34.88-38.68-42.12RatioofPeakcurrent1.0091.0121.0171.0281.0341.0371.0401.043PeakvoltagE(V)V10.1710.1890.1910.
6、1900.1870.1860.1830.183V20.2420.2550.2590.2620.2620.2620.2620.262Peakvoltagedifference(mV)71666872757679793)Accordingtotheresult,describewhycurvesshowscertaintrend,andhowpeakcurrentandpeakvoltagedifferencechangewithscanrate?Answer:Fromabovedataandcurve,wecanobtain:A.Atafixedscanrat
7、e:(1).frominitialpositivevoltagetomorereductivevalues,thecurrentbegintoflow,thenreachapeakipcanddecreaseeventually.(2).whenvoltagemovesback,theequilibriumpositionsgraduallyconvertingelectrolysisproduct(Fe2+)backtoreactant(Fe3+),thecurrentflowisfromthesolutionspeciesbacktotheelectro
8、deandsooccursintheopposite