MWCNT-TiO2-SiO2 nanocomposites possessing the photocatalytic activity in UVA and UVC

摘要

The results of studies on application of TiO2 and SiO2 co-precipitated in the presence of CNT to prepare the nanocomposites CNT-TiO2/SiO2 are presented. Nanocomposites were characterized by a large overall surface area (243-252 m~2/g), occurrence of TiO2 in the anatase form (7-8 nm) and reduced band gap energy (from 3.2 eV to 2.2 eV). The studies confirmed the role of CNT as a factor not only increasing the overall surface area of the nanocomposites but also allowing for obtaining the systems of uniform distribution of the crystallites TiO2/SiO2 on their surface and those activated with visible light. Photocatalytic oxidation carried out for 2 h using the nanocomposites resulted in 75% removal of phenol (UVC irradiation) and a complete loss of methyl orange (UVA irradiation). The nanocomposites containing about 8 wt% of CNT were the most active. Removal of the phenol and methyl orange proceeded according to the first order kinetics (k1 for UV decomposition of phenol was 0.4-0.74 × 10~(-2) min~(-1), and for Vis removal of methyl orange 2-12 × 10~(-2) min~(-1)).