Synthesis and Photocatalytic Activity of Cerium-Modified CdS-TiO2 Photocatalyst for the Formaldehyde Degradation at Room Temperature

The Ce-CdS-TiO2 photocatalysts were successfully synthesized by a simple sol-gel way and loaded on the nickel foam. The specific surface area, crystalline phase, microstructure and surface functional groups of prepared photocatalysts were characterized by Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The photocatalytic tests of Ce-CdS-TiO2 samples demonstrated that Ce as the active component plays an irreplaceable role in degradation of gaseous formaldehyde. The results showed that high Ce doping levels restrained the photocatalytic activity due to lower specific surface area, whereas moderate doping levels showed the highest photocatalytic performance due to higher specific surface area and evenly dispersion of the active component. The rate of formaldehyde degradation on 0.9 wt % Ce-CdS-TiO2, 1.5 wt % Ce-CdS-TiO2, and 2.1 wt % Ce-CdS-TiO2 photocatalysts can reach to 59, 84, and 49 %, respectively, which are higher than pure TiO2 (20 %). Ce-doping into CdS-TiO2 photocatalyst produce the Ce-O-Ti bonds, which enhanced the interaction between Ce and TiO2. The introduction of Ce increased the UV/Vis absorption of Ce-CdS-TiO2 photocatalyst. Furthermore, Ce-CdS-TiO2 possesses high photocatalytic performance, since Ce may reduce the recombination of photoexcited electrons and holes.