New Conducting Polymers for Electrochemical Ultracapacitors

  • PDF / 769,807 Bytes
  • 7 Pages / 417.6 x 639 pts Page_size
  • 55 Downloads / 234 Views

DOWNLOAD

REPORT


395 Mat. Res. Soc. Symp. Proc. Vol. 575 C2000 Materials Research Society

electrode was polished with alumina powder and rinsed with water and acetone before use. An Ag/AgC1 and Pt wire were used as reference and counter electrode, respectively. Poly(DTDA) was electropolymerized by cycling potential between -0.2 and +1.2 V (vs. Ag/AgCl) on ITO or Au in a solution containing 20 mM of DTDA monomer + 0.2 M HC1O 4 + 0.2 M LiC10 4 / CH 3CN-H 20 (1:1). The obtained poly(DTDA) has been characterized by Fourier transform infrared (FT-IR) spectroscopy on a Perkin-Elmer System 2000 (Perkin Elmer). The poly(DTDA) was investigated by using in situ UV-vis. spectroscopy on a MultiSpec- 1500 (SHIMADZU) and by using in situ SERS on a Perkin-Elmer System 2000R (Perkin Elmer). RESULTS Figure 1 shows cyclic voltammograms (CVs) for the poly(DTDA) films in aqueous solutions of various pH values. The CVs have a single redox wave in the potential range form 0.2 V to 0.4 V.

The current of the redox peaks increases as the pH value decreases.

The CVs

in lower pH values than 1.0 showed a reproducible redox couples for repeated (103-104) cycles in the potential range from -0. 1 to +0.6V. The results suggest that the poly(DTDA) can be obtained a high specific capacity and power, and that it has a good cycleabiliy in aqueous solution of low pH values. From the result of Fig. 1, the apparent formal potential (E0) was plotted against pH values of respective solutions (i.e. Pourbaix diagram) as shown in Fig.2. According to the redox reactions of the poly(DTDA) (eq. [1]), the relationship between the E0 and the pH values can be shown in the following eq. [2]. poly(DTDA)-aHl

±

poly(DTDA)"' +aH + ne-

E" = E° - 0.059a pH n

[1]

[2]

Where E0, a, andl n are the formal potential, the number of protons and electrons, respectively. The slope in pH