Abstract
In this paper, TiO2 nanowires (NWs) on Ti foils were prepared using a simple hydrothermal approach and annealing treatment. CdS quantum dots (QDs) were assembled onto the crystallized TiO2 NWs by sequential chemical bath deposition. Ultraviolet-visible absorption spectra showed that CdS adds bands in the visible to the TiO2 absorption and exhibited a broad absorption band in the visible region, which extended the scope of absorption spectrum and helped improve the photocatalytic degradation efficiency. The results of photocatalytic experiment revealed that CdS-TiO2 NWs possessed higher photocatalytic activities toward methyl orange than pure TiO2 nanowires. The degradation efficiency of 96.32% after ten cycles indicated that the as-prepared CdS-TiO2 composite exhibited excellent long-time recyclable ability and can be reused for the degradation of contaminants.
Highlights
Titania (titanium dioxide (TiO2)), a semiconductor photocatalyst, has attracted tremendous attentions in the past decades due to its chemical stability, low cost, high reusability, and excellent degradation efficiency of organic pollutants [1,2,3]
The X-ray diffraction pattern of the CdS quantum dots (QDs) on TiO2 NWs proves the existence of CdS by its three characteristic peaks (2θ = 26.4° (111), 43.9° (220), and 51.9° (311); JCPDS card no.: 65-2887), and the other diffraction peaks attribute to the anatase phase TiO2 NWs (JCPDS card no.: 21-1272 ) and Ti foil substrate (JCPDS card no.: 44-1294)
With the increase of deposition cycle number to ten, the morphologies of the TiO2 NWs for the CdS(10)-TiO2 NWs are kept almost the same with those of the CdS(6)-TiO2 NWs, while the diameters of the TiO2 NWs of CdS(10)-TiO2 seem to be larger than those of CdS(6)-TiO2, which indicates that more CdS nanoparticles are deposited on the TiO2 NW surfaces (Figure 2d)
Summary
Titania (titanium dioxide (TiO2)), a semiconductor photocatalyst, has attracted tremendous attentions in the past decades due to its chemical stability, low cost, high reusability, and excellent degradation efficiency of organic pollutants [1,2,3]. Wide bandgap (approximately 3.2 eV) restricts its photocatalytic sensitivity in the UV region with only about 4% to 5% of solar spectrum falling in the UV range. The effective use of solar energy especially visible light remains a great challenge in practical photocatalytic applications [4,5]. Low electron transfer rate and high recombination rate of photogenerated electrons and hole pairs limit the enhancement of the photocatalytic efficiency to some extent, which has been recognized as a major obstacle to meet the practical application [6].
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