Characterization and photocatalytic properties of tungsten doped TiO<inf>2</inf> coatings on aluminum obtained by plasma electrolytic oxidation

Abstract

This paper presents a recent investigation of rapid deposition of TiO2 nanoparticles on aluminum by plasma electrolytic oxidation in Na2SiO3·5H2O water based electrolyte with addition of TiO2 nanoparticles and Na2WO4·2H2O. Oxide coatings were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and grazing incidence X-ray diffraction. It was found that surface morphology, chemical and phase compositions of obtained coatings depend on electrolyte composition and processing time. The photocatalytic activity was tested by photodegrading methyl orange under simulated sunlight conditions. It was observed that photodegradation of methyl orange strongly depends on the concentration of TiO2 nanoparticles and sodium tungstate in the electrolyte and PEO treatment time. Coatings with the highest photoactivity were obtained in 4 g/L Na2SiO3·5H2O + 2 g/L Degussa P25 + 0.1 g/L Na2WO4·2H2O.