O efeito do pH na síntese de nanopartículas de Nb2O5 na fotodegradação de poluentes orgânicos e na produção fotocatalítica de H2

Abstract

been caused by the disposal of aqueous effluents and greenhouse gas emissions due to the burning of fossil fuels. In this sense, in recent decades there has been an increase in research focused on the application of heterogeneous photocatalysis in the organic pollutant degradation and production of renewable fuels. The main challenge of this technology is to develop photocatalysts with high photocatalytic activity and stability. Within this context, the present work aims to study the effect of pH and (pH = 2.0 to 6.0) hydrothermal treatment on the synthesis of Nb2O5. The samples were characterized by different techniques and the photocatalytic performance was evaluated both for the photodegradation of AML and Rod.B and to produce H2. The samples obtained at pH 4 (Nb2O5-4) and pH 6 (Nb2O5-6) by route 1 presented a transition that can Nb2O5.nH2O phase. The sample obtained at pH 2.0 (Nb2O5-2,) by routev 1 at pH 4 (Nb2O5-AP4) and pH 6 (Nb2O5-AP6) by route 2, presented a pseudo-hexagonal crystalline phase (TT-Nb2O5). N2 adsorption and desorption analyzes revealed an increasement of specific surface areas after treatment, mainly for samples obtained in pH = 6.0. The samples also presented different morphology and band gap values depending on the crystalline phase obtained. All samples were photoactivity for the degradation of Rod. B dye and the AML drug. The samples that presented the TT-Nb2O5 phase were active in the evolution of H2. The Nb2O5-AP2 sample showed greater activity in the production of H2, with 4104.5 µmol.g-1 after 8 hours, while the Nb2O5-4 and Nb2O5-6 samples, characteristic of the transition Nb2O5.nH2O phase, do not show photocatalytic activity in the production of H2, which may be associated with the low bandgap value (2.8-2.9 eV, respectively) that can result in a lower potential for oxyreduction of charge carriers. The results demonstrate that Nb2O5 is a versatile material for different photocatalytic aplplications and tht ists properties can be controlled by synthesis pH.