X-ray photoelectron spectroscopy characterization of composite TiO2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO2/PVDF ratios led to film instability. PVDF-TiO2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO2 and the role played by the PVDF film during the degradation process. (C) 2004 Elsevier B.V. All rights reserved.