Synthesis and structural characteristics of nitrogen doped TiO2 aerogels

Nitrogen doped TiO2 aerogels were obtained by sol–gel process followed by supercritical drying with liquid CO2. Urea and NH3 (25% aqueous solution) were used as nitrogen sources. The as-prepared aerogels were submitted to thermal treatments performed under different experimental conditions (temperature and heating time). Increasing the temperature from 450 °C to 550 °C a decrease about 32% and 15.4% of the particle size and surface OH groups’ concentration, respectively and an increase about 21.4% of the incorporated nitrogen in TiO2 lattice were observed. The immersion of the TiO2 aerogels in NH3 solution induced a decreasing by 48.86% and by 80% of the SBET and the aerogel porosity, respectively. The photocatalytic activity of the obtained N-doped TiO2 was found to depend mainly on the nitrogen incorporation in the TiO2 lattice.