Characterization of Bi/TiO2 nanometer sized particle synthesized by solvothermal method and CH3CHO decomposition in a plasma-photocatalytic system

This study focuses on the relationship between the plasma-photocatalytic activity for CH3CHO (acetaldehyde) decomposition and the surface properties of pure TiO2 and 10.0 mol% Bi/TiO2 nano-sized. The TiO2 and Bi/TiO2 particles, which were synthesized through the solvothermal method, exhibited a uniformly spherical anatase structure with particle size below 25 nm. The surface area was large (310 m2/g) as compared with that of pure TiO2 (140 m2/g). Bi/TiO2 adsorbed a smaller amount of water than pure TiO2. From the H2-TPR result, it was identified that Ti3+ could be easily transferred into Ti0, which affected the photoreaction, over Bi/TiO2 compared with pure TiO2. Based on these results, without H2O addition, acetaldehyde decomposition was higher on Bi/TiO2 (80% after 40 min). In particular, the by-product (mainly CH3COOH), a serious problem in the plasma system, was very small in Bi/TiO2 (below 5.0%) compared with that in pure TiO2, which was above 20.0%. However, the acetaldehyde removal slightly increased over Bi/TiO2 with H2O addition, while it remarkably enhanced over pure TiO2. This result means that H2O addition did not have a good influence on acetaldehyde removal over the Bi/TiO2 with hydrophobic property. However, it did exert a better influence on pure TiO2 with hydrophilic property.