Voltammetric Determination of Fluoride Ion Using Galvanostaticaly Grown Poly(3-hexylthiophene) Film

Abstract

Poly (3-hexylthiohene) films have been prepared by galvanostatic technique on platinum surface. The structure and surface morphology of the film was characterized by cyclic voltammetry (CV), FTIR and SEM imaging. Cyclic voltamogram of poly (3-HTh) film showed only one reduction peak at potential 0.82 V. Cyclic voltammogram of the poly (3-HTh) film when recorded in fluoride ion solution showed two redox pair at E1/2 = 0.048 V (A/A’) and E­1/2= 0.074 V (B/B’). The former peak may be attributed to [BF4]-/[BF4]2- redox couple and later peak to the presence of loosely bound fluoro-borate anions in the polymeric film respectively. Diffusion controlled process may be the possible reaction mechanism. The diffusion coefficient (D) and rate of reaction (R) for the reaction (B/B’) are calculated as 9.29 ´10-3 cm2 s-1 and 5.61 ´ 10-9 mol s-1 respectively. Poly (3-HTh) films showed detection limit as low as 2.5 mM