Síntese e caracterização de fotocatalisadores plasmônicos híbridos Au@Ag/Nb2O5 para aplicação na fotodegradação de corantes utilizando fontes de radiação visível e UV

Abstract

This work consisted in the synthesis, characterization of plasmonic photocatalysts for the application of photodegradation of violet crystal (VC), reactive black five (RB5) dyes using visible, and UV radiation sources. For the construction of the photocatalyst, bimetallic nanoparticles structured in core-shell mode with the commercial semiconductor niobium pentoxide Nb2O5 were employed, aiming to produce the hybrid plasmonic photocatalyst Au@Ag/Nb2O5. For the characterization of the synthesized materials, UV-VIS, RAMAN, SERS, SEM, polycrystal XRD, DLS and potential-ζ spectroscopic techniques were performed. The photodegradation and photolysis tests were monitored by UV Raman and SERS spectroscopic techniques for both dyes studied in this project, CV and RB5. As responses to the techniques employed it was possible to verify that both dyes under the conditions tested, with change and unchanged pH, did not undergo photolysis during the exposure time to the radiation sources used. It was possible to verify that the commercial semiconductor used as reference and matrix to obtain the hybrid plasmonic photocatalysts was able to degrade the CV dye in the presence of incident radiation; however, the same degradation was not verified when the dye tested was RB5. The degradation of CV dye was also verified with the synthesized plasmonic photocatalysts, and the effect of concentration and size of the bimetallic nanoparticles was studied in terms of catalytic efficiency. Higher catalytic efficiencies were observed than the photocatalytic process with pure Nb2O5, with the hybrid plasmonic photocatalysts synthesized with higher concentrations of nanoparticles in the photocatalytic tests with the CV dye, with up to 11% more efficiency. The degradation of the RB5 dye was not observed with the synthesized photocatalyst materials.