Abstract
AbstractCdS/TiO2composite photocatalysts were made by the method of secondary ball milling at different ball milling speeds, milling time, and material ratios. After the secondary ball milling process, parts of the samples were calcined at high temperatures. X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectroscopy (DRS) were used to observe the powder particle size, structural defect, bandgap, and absorption spectrum of the samples. Combined with the observation results, the effects of ball milling speed, time, material ratio, and high-temperature calcination on the photocatalytic performance of CdS/TiO2composite samples were analyzed. Furthermore, the methyl orange (MO) was chosen to simulate pollutants, and the photocatalytic degradation rate of CdS/TiO2composite photocatalysts for MO was evaluated under sunlight and UV irradiation conditions. The photocatalytic degradation efficiency of CdS/TiO2photocatalyst under UV irradiation is much higher than that under sunlight irradiation. The experimental results reveal that secondary ball milling can effectively promote the formation of CdS/TiO2composite nanostructure and the high-temperature calcination can reduce the bandgap width, which makes the samples easier to be excited. When the ball milling speed, time, and material ratio were respectively 400 rpm, 10 h, 25:75, and then calcined at high temperature, after 2 h of irradiation under UV light, CdS/TiO2composite photocatalysts exhibited maximum photocatalytic degradation efficiency of 57.84%.
Highlights
Nowadays, with the speedy development of the economy and increasing awareness of environmental protection, people pay more and more attention to the utilization of solar energy and photocatalytic treatment of organic pollutants by semiconductors [1]
CdS/TiO2 composite photocatalysts are made by the method of secondary ball milling, and the effects of material ratio, ball milling time, ball milling uncalcined calcined 60 uncalcined calcined
The following conclusions can be drawn from the experimental results: 1. The mechanochemical action of secondary ball milling can promote the dispersion of CdS on the surface of TiO2 and the interaction between these two, forming an effective composite nanostructure with extended light absorption edge and small bandgap width, resulting in a significant improvement on the photocatalytic degradation rate of CdS/TiO2 composite photocatalysts
Summary
With the speedy development of the economy and increasing awareness of environmental protection, people pay more and more attention to the utilization of solar energy and photocatalytic treatment of organic pollutants by semiconductors [1]. According to the degradation efficiency for MO solution, one could see that TiO2/CeO2 composite material had higher photocatalytic activity than anatase TiO2, resulting from the effective separation of electron/ hole pairs on TiO2 because of the addition of CeO2. Habib et al [38] conducted an in-depth study on the photocatalysis of TiO2–ZnO nanocomposites It can be seen from the studies listed above that in recent years, some effects have been achieved through the modification of TiO2, most modification methods are difficult to be applied and industrialized due to high preparation cost, complicated process, and limited performance improvement. Place the ball mill tanks in the ball mill after the ingredients are finished. (2) On the basis of ball milling speed and ball milling time designed in the experiment, the TiO2 and CdS powders were ground by dry ball milling. (3) After the completion of dry ball milling, anhydrous ethanol was added to make the mixed materials show sticky shape and put it into the ball mill again with the same milling parameters for wet ball milling for 2 h. (4) After the ball milling was finished, the products were collected immediately, dried and put into the resistance furnace to calcine at 400°C for 2 h. (5) The materials prepared by the above processes were fully ground for 30 min to make the samples
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