In this work, a high photocatalytic activity was attained by intercalating a Pt layer between SnO 2 and TiO 2 semiconductors, which yielded a TiO 2 /Pt/SnO 2-type heterostructure used in the discoloration of blue methylene (MB) solution. The porous films and platinum layer were obtained by electrophoretic deposition and DC Sputtering, respectively, and were both characterized morphologically and structurally by FE-SEM and XRD. The films with the Pt interlayer were evaluated by photocatalytic activity through exposure to UV light. An increase in efficiency of 22% was obtained for these films compared to those without platinum deposition. Studies on the reutilization of the films pointed out high efficiency and recovery of the photocatalyst, rendering the methodology favorable for the construction of fixed bed photocatalytic reactors. A proposal associated with the mechanism is discussed in this work in terms of the difference in Schottky barrier between the semiconductors and the electrons transfer and trapping cycle. These are fundamental factors for boosting photocatalytic efficiency.

In pursuit of higher photoactivity, Nb-doped TiO 2 powders were evaluated in the reduction of CO 2 . e replacement of Ti by Nb in the crystalline structure of TiO 2 promoted methanol formation. Nb-doped TiO 2 powders were successfully synthesized in Nb concentrations of 0.0, 0.5, 1.0, and 2.5% (w/w � weight/weight) using the Pechini method. e materials were calcined at 500°C for two hours to promote the formation of the anatase crystalline phase. After characterization, the powders were modified through an Nb 0 magnetron sputtering deposition using a metallic target in vacuum conditions of 2 × 10 −3 torr, with a deposition time of 10 minutes, and calcination again at 500°C for two hours. e resulting powders showed a surface area up to 30 m 2 /g. e Pechini method promoted the substitution of Ti 4+ for Nb 4+ as observed using XRD and XPS techniques at the crystalline structure and at the surface of the powder. Furthermore, the presence of Nb 0 was also observed at the powder's surface. e presence of Nb in the crystalline structure increased the photoactivity of powders when compared to nonmodified TiO 2 powders, while the Nb 0 deposition at the powder's surface decreased the photoactivity for all the investigated compositions.

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