EQCM Studies of Paraquat on Gold Electrode Modified with Electropolymerized Film

Abstract

This study presents a polyviologen (PV) modified gold/quartz electrode to detect paraquat (MV 2þ ) by electrochemical quartz crystal microbalance (EQCM) method. Some electroactive viologens (V 2þ ) reside in the electropolymerization achieved in pH 4.2 Britton-Robinson (BR) buffer solution containing soluble viologen oligomer. Closely examining the EQCM and cyclic voltammetry (CV) results reveal that V 2þ binds in the PV film and is electroreduced to form its relatively hydrophobic cation radical (V þ. ), which may cause the anions and hydrated water originally incorporated in the PV layer to be expelled. Moreover, while the negative potential is scanned over ¹0.55 V, the dissolved MV 2þ is reduced through V þ. to form its corresponding cation radical (MV þ.) and then becomes a dimer with the bound V þ. among the PV layer. According to our results, such dimerization possesses good reversibility so that the resonant frequency of the subsequent PV modified Au/quartz electrode can return to its initial value under the potential scanning within an appropriate region (i.e., from 0 to ¹0.7 V) and oxygen-free condition. Moreover, a linear calibration plot for detecting MV 2þ is also obtained in the range from 0 to 1.2 mM, having a detection limit of 0.1 mM.

Investigating the voltammetric reduction of methylviologen at gold and carbon based electrode materials. Evidence for a surface bound adsorption mechanism leading to electrode ‘protection’ using multi-walled carbon nanotubes

“…respectively. [1][2][3][4][5][6][8][9][10][11][12][13][14] In the anodic process, a ''poorly defined'' peak may be observed at ca. À0.9 V and has been suggested to arise from the electrode reaction:…”