电化学实验报告实验报告.docx
《电化学实验报告实验报告.docx》由会员分享，可在线阅读，更多相关《电化学实验报告实验报告.docx（6页珍藏版）》请在冰点文库上搜索。
电化学实验报告实验报告
电化学实验报告实验报告
Experimentalclasson“FuelCellandElectrochemistry”
Experimentsetup
Equipment:
CHI760Delectrochemicalstation
Threeelectrodesystem.WE:
CE:
RE:
SaturatedCalomelElectrode
Solution:
1.0×10-3mol/LK3[Fe（CN）6]+0.1MKCl
Labreport
1）PlotcurvesofLSVcurve,anddescribewhycurrentchangeswithsweepingvoltage?
Reason:
Voltageisadrivingforcetoanelectrodereactions,itisconcernedwiththeequilibriumofelectrontransferatelectrodesurface.Asthealteringofappliedvoltage,theFermi-levelisraised（orlowered）,whichchangingtheenergystateoftheelectrons.Makingtheoverallbarrierheight（ieactivationenergy）alterasafunctionoftheappliedvoltage.
（1）.Inthisreaction,whenvoltageis0.6V,thereisnoelectrontransfer,sothecurrentiszero.Withthevoltagetothemorereductivevalues,thecurrentincreases.
（2）.WhenthediffusionlayerhasgrownsufficientlyabovetheelectrodesothatthefluxofreactanttotheelectrodeisnotfastenoughtosatisfythatrequiredbyNernstEquation.Thepeakisobtaining.
（3）.Whenthereactioncontinued,itwouldgetasituationthattherewillbealowerreactantconcentrationattheelectrodethaninbulksolution,thatis,thesupplyoffreshreactanttothesurfacedecreased,socurrentdecreases.
2）PlotthecurvesofCVcurveswithdifferentscanrate;
3）FromtheCVcurves,fillthetable
Scanrate（mV/s）
20
50
100
200
300
400
500
600
Peakcurrent（uA）
Ipc
8.336
13.17
18.50
25.96
31.54
36.17
40.23
43.95
Ipa
-8.263
-13.01
-18.19
-25.26
-30.50
-34.88
-38.68
-42.12
RatioofPeakcurrent
1.009
1.012
1.017
1.028
1.034
1.037
1.040
1.043
PeakvoltagE（V）
V1
0.171
0.189
0.191
0.190
0.187
0.186
0.183
0.183
V2
0.242
0.255
0.259
0.262
0.262
0.262
0.262
0.262
Peakvoltagedifference（mV）
71
66
68
72
75
76
79
79
4）Accordingtotheresult,describewhycurvesshowscertaintrend,andhowpeakcurrentandpeakvoltagedifferencechangewithscanrate?
Answer:
Fromabovedataandcurve,wecanobtain:
A.Atafixedscanrate:
（1）.frominitialpositivevoltagetomorereductivevalues,thecurrentbegintoflow,thenreachapeakipcanddecreaseeventually.
（2）.whenvoltagemovesback,theequilibriumpositionsgraduallyconvertingelectrolysisproduct（Fe2+）backtoreactant（Fe3+）,thecurrentflowisfromthesolutionspeciesbacktotheelectrodeandsooccursintheoppositesensetotheforward.Theprocesshasanothercurrentpeakipa.Ithassamereasonoflinearsweepvoltammetry.
B.Atdifferentscanrate,theratioofpeakcurrentipc/ipaisaboutequalto1（1.009—1.043）.
C.Atdifferentscanrate,thepositionofpeakvoltagedonotaltergreatlyΔEpisaboutaconstant（66--79）.
ν（mV/s）
20
50
100
200
300
400
500
600
ν1/2（mV/s）1/2
4.472
7.071
10
14.142
17.321
20
22.361
24.495
Ip（uA）
8.336
13.17
18.50
25.96
31.54
36.17
40.23
43.95
Ep（V）
0.171
0.189
0.191
0.190
0.187
0.186
0.183
0.183
Ep’（mV）
71
66
68
72
75
76
79
79
（1）Ip--V1/2
Figure1:
PeakcurrentVSradicalsignofscanrate
Interpretation:
Itisapparentthatthepeakcurrentislineartoradicalsignofscanrate,whichsatisfythisequation:
ip=kv1/2C0.
Reason:
Thiscanberationalisedbyconsideringthesizeofthediffusionlayerandthetimetakentorecordthescan.Clearlythelinearsweepvoltammogramwilltakelongertorecordasthescanrateisdecreased.Thereforethesizeofthediffusionlayerabovetheelectrodesurfacewillbedifferentdependinguponthevoltagescanrateused.Inaslowvoltagescanthediffusionlayerwillgrowmuchfurtherfromtheelectrodeincomparisontoafastscan.Consequentlythefluxtotheelectrodesurfaceisconsiderablysmalleratslowscanratesthanitisatfasterrates.Asthecurrentisproportionaltothefluxtowardstheelectrode,themagnitudeofthecurrentwillbeloweratslowscanratesandhigherathighrates.
（2）Ep--V
Figure2:
PeakpotentialVSscanrate
（3）Ep’--v
Figure3:
thechangeofPeakpotentialVSscanrate
Interpretation:
Figure2:
showsthatthepositionofthepeakcurrentoccursatthesamevoltage.
Figure3:
showsthePeakvoltagedifferenceisconstantindifferentscanrate.
Reason:
Thecharacteristicofthiselectrodereactionhasrapidelectrontransferkineticsandthereisnochargetransferindoublelayer,sothisreactionisreversible.
升级会员 