TiO2–CeO2 composite coatings for photocatalytic degradation of chloropesticide and organic dye

Spray pyrolysis was used to deposit CeO2–TiO2 coatings on stainless steel substrates. The addition of CeO2 to TiO2 changes morphology of the coatings, causing the surface to become laced and some CeO2 ions are incorporated into TiO2 crystal lattice. Part of CeO2 is highly dispersed on the surface of TiO2. The XPS showed the simultaneous existence of Ce4+ and Ce3+ on coating surface. As the CeO2 content in composites increases from 0.5 to 20%, the band gap decreases from 3.16 to 2.88 eV, respectively. The photoactivities in the degradation of methyl orange and lindane were significantly influenced by the content of Ce in composite. For methyl orange photodegradation, the highest activity had coating with CeO2 content of 2 wt%. In contrast, the activity of coatings in lindane photodegradation gradually decreases as the CeO2 content increases. However, efficiency of CeO2–TiO2 coatings remained satisfactory for application in process of lindane degradation. Lindane conversion at 6 h of irradiation is in the range from 88% for pure TiO2 to 60% for CeO2–TiO2 coating with CeO2 content of 20 wt%. Photodegradation of lindane was enhanced on pure TiO2 sites, while methyl orange degradation is highest on composite CeO2/TiO2 species with CeO2 content of 2 wt%.