Reactive oxygen species quantification and their correlation with the photocatalytic activity of TiO2 (anatase and rutile) sensitized with asymmetric porphyrins

Modify photocatalytic TiO2 to improve its characteristics has been very scientific attention, among which we can mention the use of porphyrin dyes. In this study, they were synthesized and characterized three asymmetric porphyrins to carry out for the modification of TiO2: 5-(o-nitro-phenyl)-10,15,20-triphenylporphyrin (ONTPP, 1) and its Cu(II) (Cu-ONTPP, 2) and Zn(II) (Zn-ONTPP, 3). TiO2 (Anatase and Rutile) modified with 1, 2 and 3 were prepared in order to improve the visible photocatalytic activity of TiO2 material. The optical properties of the prepared materials (E-bg), show that the impregnation with the dyes generates a higher absorption in the visible (red shift) that the bare materials. The quantification of ROS (Reactive Oxygen Species: singlet oxygen and free radicals) showed that all rutile mixed materials have a higher efficiency as compared with the bare material. For anatase mixed materials, this behavior was only observed for the 3 porphyrin impregnated. The photocatalytic activities of TiO2(A,R)-1,2,3 were investigated by photodegradation of Congo Red in aqueous solution under the visible irradiation. The results indicated that TiO2 (A,R)-3 exhibited the highest photocatalytic activity agreeing with the higher production of ROS. (C) 2016 Elsevier Ltd. All rights reserved.