Associating low crystallinity with peroxo groups for enhanced visible light active photocatalysts

Abstract In the present study hydrogen peroxide was applied during the synthesis of titanium dioxide (TiO 2 ) photocatalysts to anchor peroxo groups onto the surface to enhance visible light excitability. The effect of changes in the pH value and crystallization temperature was investigated. As-prepared peroxo-titania were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), infrared spectroscopy (IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was investigated using phenol as model contaminant under visible light irradiation. IR and XPS measurements confirmed the presence of peroxo groups in the samples, moreover Raman and XPS measurements showed the formation of amorphous sodium titanate. Photocatalytic activity measurements pointed out, that most efficient as-prepared photocatalyst exceeded the photocatalytic performance of all reference materials. The cause of the enhanced photocatalytic activity was attributed to the enhanced visible light excitability and considerable amount of peroxo groups, which were not stable after the reusability experiments of the photocatalysts, suffering a redox reaction with the relatively high amount of Ti 3+ , resulting Ti 4+ and surface OH groups. Therefore, the loss of peroxo groups and concomitantly photocatalytic activity was observed.