Electrocatalitic behaviour of serpentinite modified carbon paste electrode

Abstract

Electrochemistry of carbon paste electrode which contained serpentinite powder and graphite in 1:1 weight ratio was examined in three-electrode cell regarding its electrocatalytic and sensing properties. For this purpose, red-ox reactions of potassium ferrocyanide in aqueous solutions as benchmark media and pesticide tebufenozide (TBF) were examined. Serpentinite characterization performed by XRPD, SEM/EDX, and FTIR confirmed the structure typical for this mineral rock. Voltammetric analyses have in all cases shown that serpentinite modified carbon paste electrode (S-CPE) possess superior electrocatalytic activity in contrast to bare CPE for the red-ox reactions of K4[Fe(CN)6]. The enlargement of the peak currents, higher electroactive surface area, and the decline of the peak-to-peak separation are a proof of reversible and faster electron transfer kinetics for S-CPE. The effect of pH on the electrochemical behaviour of TBF was investigated in Britton-Robinson buffer solutions in range from 2.0 to 7.0 and showed the best analytical performance at pH5.0. The oxidation peak of TBF appeared at +0.5V vs. Ag/AgCl under conditions optimized for the determination of TBF in the differential pulse stripping voltammetry: initial potential +0.1V, end potential +0.9V, accumulation potential −0.35V, accumulation time 120s, and the scan rate 50mVs−1.