**3. Characterization**

136 Electropolymerization

s under stirred condition so as to obtain a second layer of PPy(Ox) (~16 μm thick). The polymer coated G electrode [G/PPy/PPy(Ox)], so obtained, was washed with distilled water, dried and reintroduced in the former cell containing solution A to electrodeposit the third and final layer of PPy (~4.2 μm thick); electrolysis condition being j = 5.0 mA cm-2, t=200 s, unstirred. Prior to electrodeposition of PPy, the electrolytes (solution A & B) were degassed for 45 min by bubbling Ar and maintained under Ar atmosphere during the

Following similar method several sandwich-type binary composite electrodes of PPy and a mixed oxide belonging to both spinel and perovskite families, namely CoFe2O4 (Singh et al., 2004; Malviya et al., 2005a & b), CuxMn3-xO4 (x = 1.0 – 1.4) (Nguyen Cong et al., 2005; 2002a; 2000), NixCo3-xO4 (x = 0.3 & 1.0) (Nguyen Cong et al., 2002b; 2003, Gautier et al., 2002), La1 xSrxCoO3 (0 ≤ x ≤ 0.4) (Singh et al., 2007a), LaNiO3 (Singh et al., 2007b) and La1-xSrxMnO3 (0 ≤

Preparation of PPy/Chitosan: PPy/Chitosan composite films have been electrochemically synthesized on the Pt electrode from an aqueous solution containing 4.0 mg ml-1 chitosan, 0.3M oxalic acid and 5 mmol Py (as monomer) by using cyclic voltammetry method (Yalcinkaya, 2010). A standard 3-electrode cell containing two platinum sheets for use as the counter and working electrodes and an Ag/AgCl (saturated with KCl) electrode as the reference electrode was employed to carry out the electrolysis. The potential was scanned from – 0.60 to + 0.90 V at scan rate of 50 mV s-1. Chitosan is a natural polymer and exhibits characteristic properties, such as chemical inertness, high mechanical strength, biodegradability, biocompatibility, high quality film forming properties and low cost

(Yalcinkaya et al., 2010). The proposed structure of the composite is shown in Fig.2.

Preparation of PPy/PANI: 0.02M Py was polymerized in 0.25M H2SO4 solution at 1.0 V under inert atmosphere for 30 min. The electrode was washed with distilled water and dried at 60ºC. 0.1M pure ANI (aniline) was then electrochemically polymerized in 0.25M H2SO4 solution at 0.8 V using PPy coated electrode as working electrode under inert atmosphere for 30 min (Hacaloglu et al., 2009). Similarly, the PANI/PPy composite was prepared. In this case first of all, 0.1M pure ANI solution was polymerized. The polymer films obtained were washed with distilled water several times to remove unreacted monomer as well as the

electrodeposition process also.

**2.5 Other composites** 

x ≤ 0.4) (Singh et al., 2007c) were prepared.

electrolyte and subsequently dried in vacuum.

Fig. 2. Structural representation of the PPy/Chitosan composite
