Conducting bipolymeric composite based on poly-pyrrole and alkoxysulfonated PEDOT. Synthesis and electrocatalytic properties

Marek K. Sobkowiak 1Grzegorz Milczarek 1Roger Karlsson 2

1. Poznań Technical University, pl. Marii Skłodowskiej-Curie 5, Poznań 60-965, Poland
2. Department of Physics, Chemistry and Biology, Linköping University, Linköping 58183, Sweden

Abstract

Chemical polymerization of a 3,4-ethylenedioxythiophene (EDOT) derivative bearing a sulfonate group (EDOT-S) is reported. The polymer, PEDOT-S, is fully water-soluble and has been produced by polymerizing EDOT-S in water, using Na2S2O8 and a catalytic amount of FeCl3. Thus obtained polymer can be used as doping polyanion of poly-pyrrole (PPY). Interestingly, the PPY/PEDOT-S bipolymeric composite can be synthesized in acidic aqueous solution of PY and PEDOT-S without any external oxidized. Ambient oxygen is efficient oxidizer of the binary mixture and the biopolymer forms as a dark gel after 24h in r.t. Certain cleaning produces suspensions of PPY/PEDOT-S in water or organic solvents. The cast deposits of the biopolymer on voltammetric electrodes show substantial electrochemical activity typical of conjugated conducting polymers. The acceleration of electrode kinetics at the biopolymer modified electrodes compared to the unmodified electrodes was observed for many redox systems.

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Fig. 1.  (A) Linear sweep voltammograms recorded at a rotating glassy carbon electrode  (1000 r.p.m.) in 0.1 M HClO4 before (a) and after addition of 10 mM Fe3+ (b). The same experiment performed at the bipolymer-modified electrode is reflected by lines (c) and (d), respectively. Sweep rate: 2 mV s-1. (B) Constant potential amperometry recorded at +0.3 V vs. Ag/AgCl at the modified rotating disk electrode (1000 r.p.m.) following addition of 2.5 (a), 5 (b), 10 (c), 15 (d), 20 (e), 25 (f), 37.5 (g), 50 (h), 75 (i), 100 (j), 150 (k), 200 (l), 250 (m), 300 (n), 400 (o) and 500 μM (p) (black line). The same experiment performed on the bare electrode is reflected by the red line.

For instance, Fig. 1A compares reductive single sweep voltammograms of Fe3+ cation at unmodified and biopolymer-modified electrodes. As it seen, in the latter case the voltammogram shows a clear current plateau indicating diffusion-controlled reduction reaction. Moreover, the current onset point is shifted significantly toward higher electrode potentials. This implies that the biopolymer modified electrode can be used as amperommetric sensor of Fe3+ ions in solution. This was experimentally verified by measuring current changes following additions of increasing concentrations of Fe3+ ions. The obtained current-time tracing is shown in Fig. 1B. It is evident that the observed responses are many times higher than at the unmodified electrode. The sensitivity factor calculated from the slope of the linear regression line was 0.28 μA μM cm-2.

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Presentation: Poster at SMCBS'2011 International Workshop, by Marek K. Sobkowiak
See On-line Journal of SMCBS'2011 International Workshop

Submitted: 2011-08-25 15:33
Revised:   2011-08-29 14:09
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