Xue Juanqin

Preparation and Characterization of [Emim]BF 4 Modified Lead Dioxide Electrodes

Abstract 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.