Relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes in different electrolyte media containing substituted phenols – Voltammetric and surface morphologic studies

The relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes during the anodic oxidation of three different substituted phenols namely 2,6-dichlorophenol (DCP), 2,6-dimethylphenol (DMP) and 2,6-dimethoxyphenol (DMeoP) in aqueous acidic, acidic methanol and neutral/acidic microemulsion media were investigated using cyclic voltammetry (CV). Voltammetric analysis reveals that the anodic potential limit for the BDD electrode is higher than the GC almost in all the media. The electrooxidation of phenolic compounds takes place at high overpotential on the BDD when compared to the GC in all the media. Multisweep voltammetric experiments suggest that in the acidic methanol medium, no electrode fouling is observed for the anodic oxidation of the phenols and in the other three media containing DCP and DMP, the relative deactivation of the electrodes increases as follows: acidic microemulsion < aqueous acidic < neutral microemulsion (on the BDD) and neutral microemulsion < acidic microemulsion < aqueous acidic (on the GC). Passivation of the BDD and GC electrodes in supporting electrolytes containing the DMP were also investigated by Scanning Electron Microscopy (SEM). In all the media and on both the electrodes, the DCP shows high oxidation potential and low anodic current followed by the DMP and DMeoP.