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Prof.Dr.A.Sezai SARAC Department of Chemistry & Polymer Science & Technology

ISTANBUL TECHNICAL UNIVERSITY. Electrochemical Impedance & Morphologic Study of Poly( Propylenedioxythiophene) -Thin Films on Carbon Fiber. Prof.Dr.A.Sezai SARAC Department of Chemistry & Polymer Science & Technology. Conducting Polymer (Nano) / Carbon Fiber(Micro). Energy storage

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Prof.Dr.A.Sezai SARAC Department of Chemistry & Polymer Science & Technology

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  1. ISTANBUL TECHNICAL UNIVERSITY Electrochemical Impedance & Morphologic Study of Poly( Propylenedioxythiophene) -Thin Films on Carbon Fiber Prof.Dr.A.Sezai SARAC Department of Chemistry & Polymer Science & Technology

  2. Conducting Polymer (Nano)/ Carbon Fiber(Micro) • Energy storage • (batteries,supercapacitors) • Electrochromic devices • (smart Windows, mirrors, IR and microwave shutters) • Antistatic coatings • (displays, flat TV screens) • Semiconductor devices • (Solar Cells) • Corrosion Protection • Mechanical actuators • Bioapplications • (drug delivery systems, artificial muscles, biosensors)

  3. Supercapacitors(Electrochemical capacitors) Supercapacitors store the electric energy in an electrochemical double layer (Helmholtz Layer) formed at a solid / electrolyte interface. Advantages Highenergy density& rates ofcharge&discharge Little degradation-longer cycle life small chemical charge transfer Good reversibility Low toxicity High cycle efficiency (95% >)

  4. Cyclic Voltammetry (CV) doping; reduction or oxidation. Oxidation leaves "holes" in the form of positive charges that can move along the chain Polymer Electrogrowth extremely useful for studying electrode reaction mechanisms &electropolymerization Red ↔Ox + e-→X Monomer Free Electropolymerization mechanism of 5-membered heterocycles

  5. Electrochemical Impedance Spectroscopy (AC) The excitation signal , expressed as a function of time , has the form E(t) = E0 cos (wt) In a linear system, the response signal , It , is shifted in phase (Ф) and has a different amplitude I(t) = I0 cos (wt - Ф ) DC ohms law R= E/I =Zo [ cos(wt) / cos(wt – Ф ) ] Z = E(t) / I(t) Using EULER’s relationship Exp ( j Ф ) = cos Ф + jsin Ф Z = Z0(cos Ф + jsin Ф )

  6. Poly(3,4-alkylenedioxythiophene) Derivatives LONGER CONJUGATION LENGTH MORE ORDERED POLYMERS STABLE OXIDIZED FORM LOW Eox Poly(3,4-dialkylthiophene) Alkyl substitution to the monomer, lowers the EOX ProDOT-(Me)2 ProDOT-(Bu)2 Substitution at the 3- and 4- positions CONDUCTIVITY INCREASING DEGREE OF CONJUGATION STERIC INTERACTIONS J.Roncali,Chem.Rev.1997,97,173

  7. EXPERIMENTAL -ELECTROCHEMICAL Cyclic Voltammetric (CV)Coating: 10 mM ProDOT-(Bu)2 in 0,1 M NaClO4/ACN &Bu4NPF6/ACN at diff.scan rates (mV s-1 ) 0,0 V – 1,6 V Electrochem.Impedance Spectroscopy (EIS) 0,1 M NaClO4/ACN 100 kHz -10 mhz 3 ELECTRODE SYSTEM W.E. : CFSE , ITO ,Pt R.E. : Ag wire (checked aginst [FcII(CN)6]4- [FcIII(CN)6]3- + e-) C.E. : Pt wire

  8. Atomic Force Microscopy (AFM) NON-CONTACT Depending on the situation, forces that are measured in AFM include mechanical contact force, Van der Waals forces, capillary forces, chemical bonding, electrostatic forces, magnetic forces, solvation forces etc. --the three dimensional topography

  9. Atomic Force Microscopy (AFM)

  10. Cyclic Voltammetric film growth 100 mV/s EDX of film Bandgap- of film on ITO 5mM ProDOT-Me2 depositedat 100 mV/s, 10cycle in 0.1 M Bu4NPF6/ACN EDX results of coatings

  11. SEM & AFM Electrocoated 2,2-Dimethyl-3,4 Propylenedioxythiophene on CFME in 0.1 M Bu4NPF6/ACN at scan rate: 400 mV/s, 10 cycle. SCAN RATE EFFECT 400 mV/s uncoated

  12. SEM & AFM Electrocoated 2,2-Dimethyl-3,4 Propylenedioxythiophene on CFME 20 mV/s & 10 cycle 20 mV/s uncoated CF

  13. SEM and AFM of PProDOT-(Me)2/CFME coated at 10 mV/s and 10 cycle 10 mV/s Sarac AS,Schulz B,Gencturk A.,GilsingHD ,Surface Eng. (2008) in Press

  14. 100 mV/s SEM picture of PProDOT-(Me)2/CFME in 0,1 M Bu4NPF6/ACN scan rate:100 mV/s ,10 cycle, 2 different magnifications

  15. Capacitance vs scan rate • Cyclovoltammetric (C = charge density/scan rate) & • Nyquist plots (at low frequency) in monomer free solution & • (polymer film obtained at10 cycle, 10 mM monomer, 0.1 M Bu4NPF6/ACN). Sarac AS,Schulz B,Gencturk A.,GilsingHD ,Surface Eng. (2008) in Press

  16. DIFFERENT CHARGE (CYCLE NO) 20th cycle coated CFME uncoated CFME 40th cycle 40th cycle PProDOT-(Me)2 in 0,1 M Bu4NPF6/ACN 100 mV/s

  17. Capacitance vs scan no 5mM ProDOT-Me2 depositedat 100 mV/sin 0.1 M Bu4NPF6/ACN Sarac AS, Gilsing HD, Gencturk A, et al.Prog.Org.Coat. 60 (2007) 281

  18. parametersof the model- EIS • 1.Bulk Electrolyte resistance (Rs) • 2.Double layer capacitance(Cdl) • 3.Polarization resistance(R1) • 4.Charge transfer resistance(R2) • 5.Warburg impedance(W) • 6.CF & film capacitance • 7.Constant phase element (Q) EQUIVALENT CIRCUIT R(C(R(Q(RW))))(C(R)) Cdl Ccf Rs R1 RCF R2 • . • Ates M,Castillo J,Sarac AS, Schuhmann W, Microchim Acta 160(2008)247 • Sarac AS ,Sipahi M, Parlak EA ,Gul A , Ekinci E,Yardim F , Prog Org.Coat. 62 (2008) 96 • SaracAS, Sezgin S, AtesM, Turhan CM, Parlak EA, Irfanoglu B , Prog. Org. Coat. 62( 2008) 331

  19. Potential dependence the parameterscalculated from the model Rs,the bulk solution resistance of the polymer and the electrolyte, Cdl, double layer capacitance, R1 is the resistance of the electrolyte.(Polarization) R2 is the charge transfer, and W is the Warburg impedance of the polymer. (Electrochemicaldeposition is performed at different molarities of ProDOT-Me2 at100 mV/s, 20 cycle in 0.1 M Bu4NPF6/ACN).

  20. Poly(3,4-alkylenedioxythiophene) Derivatives 2,2 -dibutylpropylene dioxythiophene (PProDOT(Bu)2)

  21. Atomic Force Microscopy (AFM)&SEM Electrolyte effect PProDOT-(Bu)2/0,1 M Bu4NBF4/ACN PProDOT-(Bu)2/0,1 M Bu4NPF6/ACN A.S. Sarac, A. Gencturk, H.D. Gilsing, B. Schulz,C.M. Turhan, J.NanoSci.& Nanotech. 2008- In press

  22. Atomic Force Microscopy (AFM) Electrolyte effect PProDOT-(Bu)2/0,1 M LiClO4/ACN PProDOT-(Bu)2/0,1 M Et4NClO4 /ACN

  23. Atomic Force Microscopy (AFM) 0.1 M NaClO4/ACN 10 cycle 100 mV/s NaClO4 /ACN 30 cyc 100 mV/s PProDOT-(Bu)2/0,1 M NaClO4 /ACN A.S. Sarac, A. Gencturk, H.D. Gilsing, B. Schulz,C.M. Turhan, J.NanoSci.& Nanotech. – 2008- In press

  24. Atomic Force Microscopy (AFM) Electrolyte Sarac, AS. Gencturk, H.D. Gilsing, B. Schulz,C.M. Turhan, J.NanoSci.and Tech. – 2008- in press

  25. Cycle Effect of PProDOT-Bu2/Single CFME 1st CYCLE

  26. CycleEffect of PProDOT-Bu2/SCFME 1st CYCLE Randless Sevcik Equation : ip = (2.69x105) n3/2ACD1/2γ1/2 n : number of electrons, ν scan rate (V / sec)F :Faraday’s constant (96485 C / mol) A : Electrode area (cm2)R: Universal gas constant (8.314 J / mol K) T : Absolute temperature (K), and D is the analyte’s diffusion coefficient (cm2/sec).

  27. Cycle Effect of PProDOT-Bu2/SCFME 3 CYCLES 5 CYCLES (Scan rate)1/2 Scan rate (Scan rate)1/2 Scan rate

  28. Cycle Effect of PProDOT-Bu2/SCFME 10CYCLES 15CYCLES 10 CYCLES 15 CYCLES (Scan rate)1/2 Scan rate (Scan rate)1/2 Scan rate

  29. Cycle Effect of PProDOT-Bu2/SCFME 20 CYCLES Sarac AS, Gilsing HD, Gencturk A, et al.Prog. Org. Coat. 60 (2007) 281

  30. Cycle Effect of PProDOT-Bu2/SCFME AFM 1 cycle 5 cycles 3 cycles 10 cycles 15 cycles 20 cycles

  31. Cycle Effect of PProDOT-Bu2/SCFMESEM 1-3-5 Cycles

  32. Cycle Effect of PProDOT-Bu2/SCFMESEM 10-15- 20 cycles

  33. Cycle Effect of PProDOT-Bu2/SCFME EIS BODEPHASE Sarac AS, Gencturk A, Schulz B, et al.Journal of Nanoscience and Nanotechnology 7 ((2007)3543

  34. Cycle Effect of PProDOT-Bu2/SCFME Cdl : 1 / IZimI BODE MAGNITUDE

  35. Cycle Effect of PProDOT-Bu2/SCFME NYQUIST CLF : 1/ 2π f Zim

  36. Cycle Effect of PProDOT-Bu2/SCFME EQUIVALENTCIRCUIT BODEPHASE

  37. Cycle Effect of PProDOT-Bu2/SCFME EQUIVALENT CIRCUIT BODE

  38. Cycle Effect of PProDOT-Bu2/SCFME EQUIVALENTCIRCUIT NYQUIST PLOT

  39. Cycle Effect of PProDOT-Bu2/SCFME EQUIVALENT CIRCUIT R(C(R(Q(RW))))(C(R)) Cdl Ccf Rs R1 RCF R2

  40. Cycle Effect of PProDOT-Bu2/SCFME EQUIVALENTCIRCUIT Cdl Ccf Rs R1 RCF R2 Rs,the bulk solution resistance of the polymer and the electrolyte, Cdl, double layer capacitance, R1 is the resistance of the electrolyte. R2 is the charge transfer, and W is the Warburg impedance of the polymer.

  41. Potential Effect of PProDOT-Bu2/CFSE EQUIVALENT CIRCUIT

  42. Potential Effect of PProDOT-Bu2/CFSE 0.1 – 1.1 V After 1.1 V

  43. Substrate Effect of PProDOT-Bu2 Pt SCFE ITO

  44. Substrate Effect of PProDOT-Bu2

  45. Conclusion • Equivalent circuit simulations corresponding to the polymer modified microelectrodes calculated and suggested values of the each component was ingood correlation withexperimental data. • Typical CV of the polymeric film exhibits very well-defined and reversible redox processes. • Porous nanostructures were obtained with high capacitances • The impedance changes with film thickneses & morphologies, between 0.1 V and 1.4 V. • A potential range was found to be the most suitable condition for the PProDOT-Bu2 modified microelectrodes as supercapacitor components

  46. acknowlegements • Dr.B.Schulz – Potsdam University & IDM Teltow Germany • Dr.Gilsing –IDM Teltow Germany • M.Turhan –Univ.of Nurnberg &Istanbul Tech Univ • A.Gencturk - Istanbul Tech Univ

  47. Thank you Istanbul Bosphorous

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