Preparation and Assessment of a Polysafranin/Multiwall Carbon Nanotube-Nafion Hybrid Film–Modified Carbon Paste Electrode and Its Performance as an Easy Sensing Probe for H2O2 and Cu2+

Abstract

A polysafranin/multiwall carbon nanotube-Nafion hybrid film was prepared by electropolymerizing safranin on the surface of a MWCNT-Naf/CPE. The modified electrode was evaluated as an electrochemical sensor for hydrogen peroxide (H2O2) and Cu2+ in the presence of H2O2, in 0.1 M Tris buffer (pH 6.0) using cyclic and differential pulse voltammetric methods. The electrode showed a pair of well-defined and quasi-reversible redox peaks with formal potential (E°΄) = 0.290 ± 0.005 V versus Ag/AgCl corresponding to the polysafranin redox couples. The effects of the experimental variables on the electrode behavior regarding polymerization conditions, electrolyte pH, and MWCNT concentration were investigated to obtain optimum experimental conditions. The investigation of differential pulse voltammetric results showed that the polysafranin film at the modified electrode surface acts as an effective catalyst for H2O2 r and Cu2+ reduction in the presence of H2O2. Under optimum conditions, the modified electrode exhibited a linear dynamic range of 4.5–23.0 mM and a sensitivity of 17.4 ± 0.4 μA mM-1 cm‑2 toward H2O2 with a detection limit of 0.6 mM (3Sbl/m). In the presence of 17.0 mM H2O2, the electrode showed a linear response range of 1.0–80.0 μM and a sensitivity of 7.6 ± 0.2 μA μM‑1 cm‑2, with a detection limit of 0.1 μM (3Sbl/m) for Cu2+. In the next step, using differential pulse voltammetry, the response of the electrode to Cu2+ was studied in the presence of interfering metal ions that can promote Fenton’s reaction. The results showed that Fe2+, Co2+, and Al3+ produce interference at more than 5-, 2- and 10-fold ratios ([cation]/[Cu2+]) respectively.