Abstract: A titanium electrode (Ti) modified with Nafion-carbon nanotubes film (Nafion-CNTs) and electro-deposition of lead dioxide adding lanthanum (La-PbO2) was constructed and used to degrade methyl orange (MO) benefiting from the feature of low resistance and the special construction of carbon nanotubes. Infrared spectroscopy shows that activated CNTs are rich in active functional groups such as hydroxyl and carboxyl groups, which increase the activity and hydrophilicity of CNTs. The surface morphology of the modified electrode was characterized using scanning microscopy and high-power optical microscope. The crystal structure on the surface of the electrode exhibits irregular protrusions of 5 μm arranged in a dense pattern. Analysis of the crystal structure of the electrode surface layer deposited by electrolysis was conducted using X-ray diffraction (XRD). It is known that lanthanum enters the crystal structure of PbO2 and causes changes in the lattice structure.The electrochemical behavior of the modified electrode was investigated by a conductivity test. The degradation capability of modified electrode was investigated by determining the formation of hydroxyl free radical and the removal of MO. The electrocatalytic performance of the modified electrode is significantly enhanced. The degradation efficiency was evaluated by degrading phenol under different current, pH and plate spacing. The experimental results indicated that the Ti/Nafion-CNTs/La-PbO2 electrode displayed a low conductivity and high radical productive ratio. The MO removal rate reached 70.52 % at 20 min, and thoroughly degraded after 60 min, which was a remarkable enhancement compared to the unmodified Ti/PbO2 electrode. Using the prepared modification electrode as the anode, phenol was treated under different conditions, and the results showed that he removal rate was positively correlated with the current and stable at plate spacing of 10 mm. The maximum removal rate occurred at pH 6 and plate spacing of 10 mm.

Key words: Titanium anode, Carbon nanotube, Nafion, Advanced oxidation