Highly stable palladium-loaded TiO2 nanotube array electrode for the electrocatalytic hydrodehalogenation of polychlorinated biphenyls

Palladized TiO2 nanotube array electrode was prepared for the electrocatalytic hydrodehalogenation (HDH) of 2,4,5-trichlorobiphenyl (2,4,5-PCB). The TiO2 nanotube array electrode was successfully fabricated by anodic oxidation method, and Pd was loaded onto the TiO2 nanotubes by electrochemical deposition. The morphology and structure of the nanotube array electrodes with and without Pd catalysts were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the diameters and lengths of the TiO2 nanotubes were 30-50 nm and 200-400 nm, respectively. The particle size of the Pd was about 12 nm. Electrocatalytic HDH of 2,4,5-PCB with the Pd/TiO2 nanotube array electrode was performed in H-cell reactor. Under a constant potential of -1.0 V, the HDH efficiency of 2,4,5-PCB was 90% and the biphenyl yield was 83% (15% current efficiency) within 180min at the Pd/TiO2 nanotube array electrode. Compared with the Pd/ Ti electrode, the Pd/TiO2 nanotube array electrode exhibited higher HDH efficiency and stability. Additionally, the effect of the primary HDH factors was also investigated.