Preparation and Characterization of [Emim]BF4 Modified Lead Dioxide Electrodes

Modified PbO2 electrodes were prepared by electrodeposition in the presence of ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([Emim]BF4). The electro-catalytic performance of the prepared electrodes for the electrochemical degradation of phenol in aqueous solution was investigated. The COD removal of phenol simulated wastewater followed pseudo-first-order rate kinetics. The rate constant with [Emim]BF4-modified PbO2 electrodes was 0.007 39 min−1, higher than 0.003 83 min−1 obtained with non-modified PbO2 electrodes. The microstructure of the electrodes was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties were investigated by Mott-Schottky, steady-state polarization and linear sweep voltammetry techniques. Results indicate that PbO2 coatings with compact and regular morphology, a higher degree of crystallinity and higher content of oxygen in crystal lattice are anodically grown on Ti substrate from electrolyte containing [Emim]BF4. Steady-state polarization tests show that oxygen evolution overpotential on modified electrodes is significantly higher than that on non-modified ones. Mott-Schottky tests reveal a markedly lower content of oxygen vacancy in modified PbO2 samples as compared with the non-modified ones. It is suggested that the enhanced electro-catalytic activity of the [Emim]BF4-modified PbO2 electrodes towards phenol degradation arises largely from its lower content of oxygen vacancy, which decreases the probability of oxygen transferring from more effective
- OH into less desirable Olat at the electrode surface.