| In recent years, semiconductor photocatalysis has attracted extensive attention for its potential applications in solving environmental pollution and energy shortage. However, the existing research on TiO2 photocatalysis material was still hindered by the narrow spectral response range, low quantum efficiency and poor recycling performance. Researchers used the ion doping, noble metal and semiconductor coupling method to expand the spectral response range. The special band structure of semiconductor coupling could improved the photocatalytic activity is that the excitation of conduction band-gap formed a space-charge layer at the contact interface in semiconductor to promote the charge-transfer rate and prolong the lifetime of carriers. Hence, the synthesis and performance in degradation of organic pollutants and the photocatalytic mechanism were studied in this paper, the main research work is as follows:The Ag2O-Ti O2/sepiolite composites were synthesized via a facile sol–gel and impregnation method. The phase, crystal structure and optical absorption properties of the as-prepared samples were analyzed by the systematic characterization. XRD analysis indicates that TiO2 could exist as a mixture of small nanometer-sized anatase and rutile phases in these samples. The results of TEM and HRTEM conjectured that the heterojunction structure of the Ag2 O and TiO2 was formed in the composites and further con?rmed that the coexistence of the Ag2 O and TiO2 two components in the samples. UV-vis DRS analysis revealed that the Ag2O-Ti O2/sepiolite composites shows a slight red-shift as compared to that of Ti O2/sepiolite. N2 adsorption-desorption results suggest that the specific surface areas of Ag2O-Ti O2/sepiolite composites increased obviously compared that of the sepiolite, which is in favor of the catalytic abilities of the catalysts. The characterization results showed that the semiconductor coupling of TiO2 expanded its the spectral response range, which is beneficial to improve the catalytic abilities of the composites.The photocatalytic activity of Ag2O-TiO2/sepiolite composites was investigated by the two kinds of aqueous solutions(acid red G and 4-NP solution) and gas(formaldehyde) photocatalytic reaction system. The ARG and 4-NP were chosen as the goal pollutant to study the calcination temperature effects of preparation conditions on the photocatalytic activities of catalyst. The results indicated that Ag2O-Ti O2/sepiolite composites showed good performance in the photocatalytic degradation of organic dye ARG under visible light irradiation, the concentration of ARG and 4-NP solution were decreased by 98% and 90% respectively, which exhibit an enhanced performance than the TiO2/sepiolite and P25. The as-prepared samples showed effectively in the photocatalytic degradation of formaldehyde gas under visible light irradiation.The terephthalic acid photoluminescence probing technique and quenching results are proved that the generation of O2?- and h+ as the key factor in the photo-oxidation process of the target pollutant by Ag2O-TiO2/sepiolite composites. Theoretically, we calculated the conduction band of Ag2 O nanoparticles have excessive negative charges which easily adsorb on Ti O2 nanoparticles with positive charges, which could promote the separation of the photo-induced carriers, and enhance the photocatalytic efficiency. The sepiolite clay as the substrate for Ag2O-TiO2 coupled semiconductor can stabilized photocatalyst, moreover, the specific surface area, the active sites, the adsorption properties and the recycling from wastewater are improved by the carrier. |
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