Study on Electrochemical Oxidation of m-Nitrophenol on Various Electrodes Using Cyclic Voltammetry

The electrochemical oxidation behavior of m-nitrophenol (m-NP) was studied comparatively on glassy carbon electrode, Pt electrode, PbO2 electrode, SnO2 electrode, and graphite electrode using cyclic voltammetry. The cyclic voltammetry measurements were performed in acidic (1 M H2SO4, pH 0.4), neutral (1 M Na2SO4, pH 6.8), and alkaline (1 M NaOH, pH 12.0) media to investigate the effect of pH value on the oxidation of m-NP. The fouling of electrodes was also studied during cyclic voltammetry measurements. The results indicate that both of the electrode material and the pH value of supporting electrolyte had a significant influence on the oxidation of m-NP. In acidic medium, m-NP was irreversibly oxidized on glassy carbon electrode, Pt electrode, SnO2 electrode, and graphite electrode at 1.23, 1.26, 1.26 and 1.27 V, respectively, while there was no any oxidation peak for PbO2 electrode. In a neutral medium, m-NP yielded well-defined oxidation peaks on all electrodes, although the height and potential of the peaks depended on the material of electrodes. In the alkaline medium, the m-NP could be directly oxidized only on glassy carbon electrode and graphite electrode, but their peaks were not well defined because the oxidation of m-NP occurs closer to oxygen evolution potential region. In addition, the oxidation peaks appeared at the lower potential value in the alkaline medium than in neutral and acidic media. Under all conditions, except in the alkaline solution and on glassy carbon electrode, the passivation of electrodes occurred during continual scans.