Desenvolvimento de nanocompósitos de TiO2/Ag3PO4 com alta área interfacial para fotodegradação de corantes orgânicos catiônicos e aniônicos sob luz visível

Abstract

Industrial processes play a crucial role in modern society, and numerous environmental issues arise due to the accumulation of raw materials, inputs, and process inefficiencies. Heterogeneous photocatalysis is emerging as a promising technology to address these issues, providing an approach for the photo-oxidative mineralization of organic compounds. Although TiO2 is one of the most widely used semiconductors in the photocatalytic process, it shows a fast recombination rate of the photogenerated electron-hole pairs and operates only under ultraviolet illumination due to its high band gap. Thus, this study explores two synthesis routes for TiO2/Ag3PO4 nanocomposites with crystal sizes smaller than 30 nm as a strategy to improve the interfacial area between both phases and its photocatalytic efficiency for degrading both cationic and anionic dyes. The materials were prepared by in-situ precipitation of Ag3PO4 in a TiO2 nanocrystalline suspension. All prepared nanocomposites exhibited higher photocatalytic efficiency than pure Ag3PO4 under visible light irradiation. The best materials from the optimal synthesis route exhibited kinetic constants up to 13 and 5 times higher for the degradation of Rhodamine B and Methyl Orange, respectively. The composite prepared with a TiO2/Ag3PO4 molar ratio of 25/75 degraded approximately 99% of Rhodamine B, while the composite obtained with a 50/50 ratio degraded about 96% of Methyl Orange in 180 minutes. These samples also outperformed a nanocomposite photocatalyst synthesized from Degussa P25, which has been used as a reference catalyst in many studies. It is suggested that the high photocatalytic efficiency of these nanocomposites is due to the increased interfacial area between TiO2 and Ag3PO4 crystals, which is related to the synthesis strategy used in this study