TiO2 nanotubes impregnated with Au nanoparticles: Characterization and application in carbendazim and atrazine degradation

TiO2 nanotube electrodes were impregnated with Au nanoparticles (Ti/TiO2-Au) using different procedures. The electrodes were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and photoactivity. The best results were obtained for the electrode prepared by photochemical reduction using a HAuCl4 0.06 mol L-1 (pH 7) solution. The electrode was applied in the photoelectrocatalytic degradation of pesticides (carbendazim and atrazine). Photoelectrocatalytic oxidation of 1 x 10-5 mol L-1 of carbendazim (CBZ) allowed 100 % degradation within 10 min, monitored by UV/Vis absorbance, using the best conditions 0.05 mol L-1 NaCl (pH 2) at +1.0 V vs Ag/AgCl under UV irradiation. The same conditions applied in the atrazine degradation led to 100 % chromophore removal after 60 min of treatment. The performance of the Ti/TiO2-Au anode was compared to that of Ti/TiO2-Ag and Ti/TiO2. The byproducts were monitored by MS/MS. These results indicate that the Ti/TiO2-Au anode prepared by anodization and Au photochemical reduction impregnation is an efficient photocatalyst (semiconductor) for pesticide degradation.