Photocatalytic Performance and Kinetic Studies of a Wood Surface Loaded with Bi2O3-Doped Silicon–Titanium Composite Film

In this paper, a surface self-cleaning wood was obtained by loading Bi2O3-doped silica–titanium composite film on the surface of wood by the sol–gel method. The effects of different Bi doping amounts on the structure and photocatalytic properties of the modified wood were investigated. The doping of Bi2O3 inhibited the growth of TiO2 crystals and the phase transition from anatase to rutile. In addition, Bi2O3 could improve the photocatalytic activity of the composite film by appropriately reducing the grain size of TiO2 and increasing the crystallinity of TiO2. Furthermore, doping with Bi2O3 shifted the absorption wavelength of the wood samples back into the visible range, indicating that the increase in Bi content favoured light absorption. The wood samples loaded with Bi2O3-doped Si–Ti composite membranes had the best photocatalytic activity and the highest reaction rate when n (Ti):n (Bi) = 1:0.015. Degradation rates of 96.0% and 94.0% could be achieved for rhodamine B and gaseous formaldehyde, respectively. It can be seen that wood samples loaded with Bi2O3-doped Si–Ti composite films on the surface exhibit excellent photocatalytic activity against both gaseous and liquid pollutants.