Construction And Catalytic Properties Of The Layered HNbWO₆Nanocomposites

In recent years, the synthesis, modification and catalytic application of the layered transition metal oxides have become one of the hot research topics of catalytic materials, and they have great application value. In order to achieve the higher interlayer channel, higher acid amount and acid strength, larger surface area and the appropriate band gap, and in addition to improve their physical and chemical activity, researchers mainly modify the layered materials through ion-exchange, pillar, dipping and exfoliation-assemble methods. Therefore, superior theoretical basis and feasibility to design assemble the new material based on the layered LiNbWO6, and the practical application value is high.In this article, the precursor LiNbWO6was synthesized by a solid state reaction method, and then the precursor were modified by ion-exchange, pillared and exfoliation-assemble method, etc. The physico-chemical properties of the modified mateiails were characterized by means of XRD, SEM, NH3-TPD, H2-TPR, TG-DTG, FT-IR, Raman and N2adsorption-desorption. The acid catalytic and photocatalytic performances were evaluated by toluene nitrification and the degradation of methylene blue (MB) and rhodamine B (RhB). The results as follows combined with characterization and experimental:According to the results of XRD, SEM and N2adsorption-desorption test, the interlayer channel was increased significantly, and the specific surface area was increased to131.1m2·g-1after exfoliation although the layered structure was suffered some damage. HNbW06nanosheet not only preserved the original Nb-OH bond, but also formed new Nb-OH according to Raman spectra. The conversion rate and the p/o ratio of toluene nitrification were increased to99.7%and1.12. HNbW06and nanosheets showed good results in photodegradation MB and RhB, the photocatalytic activity of nanosheet increased significantly due to the increase of surface area, but the two kinds of dye degradation effect is different, the degradiation rate of the former is close to100%, but that of the later is only about90%.HNbWO6/Fe2O3and HNbWO6ZnO composite materials were prepared by exfoliation-assemble method, the Raman and H2-TPR results illustrated that there is an obvious interaction between subject and object. The N2adsorption-desorption analysis showed that the specific surface areas of them were156.0m2·g-1and106.5m2·g-1, and the pore volumes were0.395cm3·g-1and0.204cm3·g-1, respectively. However, the pore size distribution of the later is relative concentrated, which may be the one reason why the latter had a smaller surface area. The nanosheets and composite materials show more excellent effect in photodegradition MB under visivle irradiation (approaching100%), the activity order of the photocatalysts are HNbWO6nanosheet≥HNbWO6/Fe2O3> HNbWO6ZnO> ZnO> Fe2O3. The photodegradation effect of the materials has some correlation with their specific surface area, which indicates that the surface area is an important factor to affet the photodegradation.