| Zinc oxide has been used as semiconductor photocatalyst due to itslow-cost, easily obtained, non-toxicity, high stability and efficient degradationof organic pollutants under UV light irradiation. However, there still existsome problems to be solved urgently, such as the rapid recombination rate ofthe photogenerated electron-hole pair, the narrow light response range,immobilization and recycling and reuse. Consequently, more efforts havefocused on the development of new visible light-responsive sensitizedphotocatalysts. Resent reasearches indicate that semiconductor coupling is aneffective method of modifying Zinc oxide in order to realize visible lightphotocatalytic activity. Up to date, a number of two-component coupled ZnOcomposite photacatalysts have been reported and shown more efficient chargeseparation and excellent photocatalytic efficiency. In contrast, few visible lightphotocatalysts were developed by semiconductor coupling ZnO with othersemiconductors. Therefore, the preparation of new visible light photocatalysthas profound theoretical and practical meaning.In the present work, ZnO/SnO2binary couping films were fabricated by layered double hydroxide （LDH） slurry coating/sintering technique.NiO/ZnO/SnO2ternary couping powders were prepared by thermaldecomposition of LDHs. The structure, composition and microstructure of thesamples were characterized by XRD, UV-Vis, TG-DTA, FT-IR, ICP, SEM,EDS, BET, XPS and Raman. Methylene blue （MB） and rhodamine B （Rh B）were chosen as degradation agent to evaluate the visible light and UVphotocatalytic activity, respectively.（1） ZnSn-LDHs/ZnSn（OH）6composite suspension with different[Zn2+)]/[Sn4+] initial molar ratios were fabricated by co-precipitation method atconstant pH. The composite suspension were coated on-Al2O3substrates andthen calcinated at500700℃. The photocatalytic activity of theZnSn-LDHs/ZnSn（OH）6films and ZnO/SnO2films were estimated using RhBdye under UV light irradiation. The samples derived from LDHs with[Zn2+)]/[Sn4+] initial molar ratio of2/1and calcinated at700℃exihibitexcellent photocatalytic properties.（2） NiZnSn-LDHs/ZnSn（OH）6composite suspension with different[Ni2+]/[Zn2+]/[Sn4+] initial molar ratios were prepared by co-precipitationmethod at constant pH. The suspension precursors were dried at roomtemperature. The bulk precursors were triturated and then calcinated at600800℃. The photocatalytic activity of the NiO/ZnO/SnO2powders wasestimated using MB dye under visible light irradiation. The samples derivedfrom [Ni2+)]/[Zn2+)]/[Sn4+] initial molar ratio of0.4/3/1and calcinated at700℃ exihibit excellent photochatlytic properties. |
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