Synthesis, characterization and photocatalytic activity evaluation of TiO2 – ZnO nanocomposites: Elucidating effect of varying Ti:Zn molar ratio

Selective Removal of Photocatalytically Active Anatase TiO2 Phase from Mixed‐Phase TiO2‐ZnO Nanocomposites: Impact on Physicochemical Properties and Photocatalytic Activity

“…Also, the decolorization extent at the end of 240 min was observed to be higher under visible irradiation than under UV irradiation, possibly due to the dye sensitization effect. [20] However, in TZ-1:1, no significant difference in kinetics or extent of decolorization under both UV and visible irradiation was observed. The extent of decolorization at the end of 240 min was compared to that of commercially available TiO 2 as well as TiO 2 nanoparticles synthesized without ZnO (Figure 9).…”

“…Synthesis and Characterization of TiO 2 -ZnO Nanocomposites: The sol-gel process proposed by Menon et al was adopted for the present study. [20] Briefly, TiO 2 sol was prepared by adding TIP into EtOH under vigorous stirring in acidic environment. Surfactant (SDS) solution was added dropwise, followed by the addition of the zinc precursor (ZN), such that the Ti:Zn molar ratio was 1:0.1 (TZ-1:0.1), 1:0.2 (TZ-1:0.2), 1:0.3 (TZ-1:0.3), and 1:1 (TZ-1:1).…”

“…Various phases existing together in contact with one another may tailor the bandgap of the nanocomposite. [20] The presence of defects may be another factor that can decrease the bandgap of the photocatalyst. [18,[38][39][40] Oxygen vacancies may cause defect states within the forbidden gap and form new energy levels, termed as midgap states.…”

“…[ 19 ] Interestingly, Menon et al showed that anatase phase transformations were limited to only certain planes of anatase and that anatase phase existed in preferred orientation even when the 100% intensity plane underwent transformation. [ 20 ] Further, it was observed that superior activity was seen in the nanocomposite that was predominated by rutile TiO 2 and zinc titanates, while only negligible anatase was present in preferred orientation. [ 19 ] These observations were contradictory to reports that indicated the presence of rutile or zinc titanates, or anatase transformation to rutile, to be detrimental to photocatalytic activity.…”

“…[19] These observations were contradictory to reports that indicated the presence of rutile or zinc titanates, or anatase transformation to rutile, to be detrimental to photocatalytic activity. [11,20,21,22] The objective of this study was to understand the role of anatase phase of TiO 2 on the photocatalytic activity of TiO 2 -ZnO nanocomposites. To address this, selective dissolution of anatase phase using HF was conducted.…”