Silicomolybdate doped polypyrrole film modified glassy carbon electrode for electrocatalytic reduction of Cr(VI)

Abstract

Electrically conducting polypyrrole (PPy) film doped with silicomolybdate (SiMo12 \( {\text{O}}^{{{\text{4 - }}}}_{{{\text{40}}}} \) or SiMo12) was synthesized by electrochemical polymerization. The synthesized film is capable of fast charge propagation during redox reactions in strong acid medium 0.2 M H2SO4 solution. Electrochemical quartz crystal microbalance was used to study the mechanism and amount of SiMo12 doped in the PPy matrix. The modified electrode surface was characterized by using atomic force microscope technique, and it was found that the minimum and maximum globule size were estimated to be in the range of 50–200 nm. The thickness of film was measured to be approximately 30 ± 10 nm. The modified electrode shows electrocatalytic activity towards reduction of Cr(VI) and periodate. The rate constant and optimal film thickness were determined for electrocatalytic reduction of Cr(VI) by using rotating disc electrode experiment. Analytical characterization of the SiMo12 doped PPy film modified electrode was demonstrated by flow injection analysis (FIA) technique and shows good stability for 16 continuous injections for Cr(VI) reduction with RSD of 1.6%.