Use of WO₃:TiO₂ heterostructures in the photodegradation of dyes

Full text: The semiconductor most used in photocatalysis is TiO₂ and a junction with other semiconductors can be performed. In previous studies (OLIVEIRA, 2014), particles of TiO₂ , WO₃ and TiO₂ :WO₃ heterostructures were synthesized by the Polymeric Precursor Method and used in the phodegradation of dye Rhodamine B (RhB). Several compositions were evaluated and the sample that had the highest photocatalytic activity was TiO₂ :WO₃ with massic ratio of 50% of each oxide (W50). Therefore, this composition was used in present work to degrade different dyes: RhB, Methylene Blue, Methyl Orange. Heterostructures TiO₂ :WO₃ were characterized by XDR, FEG, PL and BET. In XRD analysis, it was detected in W50 diffraction peaks not well defined, indicating that the particles are amorphous. BET shows that the largest surface area was the W50 (107.6 m² .g^-1). By FEG it was verified W50 showed more homogeneous morphology in relation to others samples. By PL W50 demonstrated the lowest rate of electron recombination. Then, from the results described, possibly W50 has the best photocatalytic activity because its particles have a high surface area, amorphous feature, lowest rate of electron recombination and a formation of heterostructure more effective. The photocatalytic essays were performed in the UVC region and at room temperature. It was observed that the presence of catalysts accelerated degradation of three dyes analyzed. Due of the exponential profiles observed for the kinetic degradation of dyes under UV light, it can suggest that the reaction is first-order with respect to the dyes. Thus, it can conclude that the heterostructure (W50) is efficient in the photodegradation of different compounds. Reference: [1] OLIVEIRA, J. A. Obtenção de partículas de WO₃ :TiO₂ aplicadas a Processos Oxidativos Avançados para despoluição de águas. Trabalho de Conclusão de Curso. UNIFAL (MG). 2014. (author)