Comparative studies on the electro-catalytic oxidation performance of surfactant–carbon nanotube-modified PbO2 electrodes

In this study, carbon nanotube (CNT) modified PbO2 electrodes were fabricated using electrodeposition method. The influence of adding cationic surfactant–cetyltrimethylammonium bromide (CTAB) or anionic surfactant–lauryl benzene sulfonic acid sodium (LAS) into electrodeposition solution on the performance of CNT–PbO2 electrodes was compared. The morphology, elemental composition and phase composition of PbO2, CNT–PbO2, CTAB–PbO2, LAS–PbO2, CTAB–CNT–PbO2 and LAS–CNT–PbO2 electrodes were characterized using scanning electron microscope (SEM), X-ray energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Linear sweep voltammetry (LV) and cyclic voltammetry (CV) were also utilized to study the electrochemical performance of different electrodes. The results showed that more CNT could be doped into the PbO2 film by the synergetic action of LAS, and the LAS–CNT–PbO2 electrode has a higher activity than other PbO2-based electrodes. In addition, fluorescence spectrum technique was used to determine the amount of hydroxyl radical produced during the electro-catalytic oxidation process, which gave the direct evidence that the generation capability of hydroxyl radical on the surface of LAS–CNT–PbO2 was stronger than those of other PbO2-based electrodes. Mineralization experiments of 4-chlorophenol (4-CP) also indicated that the electro-catalytic activity of LAS–CNT–PbO2 electrode was superior to other electrodes. Stability tests at 60 °C and in 2.0 M aqueous H2SO4 with an anodic current density of 1.0 A cm−2 showed that the LAS–CNT–PbO2 electrode had the highest electrochemical stability.

► Carbon nanotube (CNT) modified PbO2 electrodes were prepared. ► The effect on CNT–PbO2 of different surfactants was compared. ► More CNT could be doped by the synergistic effect of anionic surfactant–LAS. ► A higher activity and stability was obtained by LAS–CNT–PbO2 electrode.