Decomposition of NO in gas phase by gold nanoparticles supported on titanium dioxide synthesized by the deposition–precipitation method

In the present work, the synthesis, characterization and photoactivity concerning the nitrogen monoxide (NO) decomposition of sol–gel Au/TiO2 photocatalysts are reported. TiO2 was prepared by gelling titanium (IV) isopropoxide, and gold nanoparticles were added by the deposition–precipitation method with urea. The catalysts with different gold concentrations were characterized by the following techniques: BET, XRD, UV–vis and dark-field TEM. It was found that by using this synthesis method, a high dispersion of gold nanoparticles on TiO2 was reached (4.4–6.7 nm), and the obtained structure lead to a band gap energy that is lower than the one observed for undoped TiO2. A NO + O2 mixture (150 ppm) was used to evaluate the photocatalytic activity in situ, at room temperature, under atmospheric pressure and a UV lamp was used as radiation source. The photocatalytic conversion of nitrogen monoxide (NO) was followed by FTIR, which reached 96% in 60 min. The Au/TiO2 materials showed an enhanced photocatalytic activity when compared with the reference TiO2.