| Considerable attention has been paid to layered composite semiconductor catalyst for its unique structural features and wide applications in solar energy conversion and environmental purification. Apart from the porous textures and high specific surface areas, the high catalytic efficiency of this composite semiconductor is predominantly attributed to the effective separation of photo-generated electron-hole between the guest and host.In this paper, the host semiconductor catalyst KNbTiO5and KNb3O8were synthesised by a solid-state method. Simultaneously, the technology of ion-exchange, exfoliation were used to modified the layered materials as-prepared. Different methods were used to prepared the guest nanoparticles, then the layered composite Nb-based catalysts were fabricationed via an exfoliation-restacking route. The catalysts were characterized by means of powder X-Ray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR). Scanning electron microscopy(SEM). Transmission electron microscopy(TEM), UV-visible diffuse reflectance spectroscopy(UV-vis DRS), Thermal analysis(TG-DTA) and other physical and chemical technology. The photocatalytic activity in the degradation of methylene blue(MB) and the photocatalytic oxidation properties in degradation of organic sulfide were charactered by UV-visible diffuse reflectance spectroscopy and Infrared spectroscopy techniques.The results indicated that:the host semiconductor materials KNbTiO5and the KNb3O8which were synthesised by a solid-state method exhibited an obvious layered structure and integrity crystal. The d-spacing of HNbTiO5; and HNb3O8changes after acidification. For Fe(OH)3pillared HNbTiO5and HNb3O8, Scanning electron microscopy showed that its maintain a good layered structure on its morphology. XRD results revealed that the main diffraction peak shifted toward a low angle, which indicated that because of the intercalation of the guest semiconductor nanoparticles the layer spacing increased. While for the Fe2O3pillared HNbTiO5and HNb3O8, the XRD patterns illustrated that the main crystal diffraction peak have shifted toward a low angle, which indicated that the interlayer spacing increased.The composed material HTiNbO5-Fe(OH)3exhibits high photocatalytic activity in degradation of methylene blue(MB). under visible light radiation, within a certain range. increasing the anloum of catalyst can significantly inprove the degradation rate.When the catalyst amount os0.5mg·L-1degradation rate can teach to91.4%which indicated that MB has been completely degraded.In static conditions. both KTiNbO5and KNb3o8have litter adsorption activity of ethanetlliol.so there was no absorption peak of ethanethiol the IR spectra under UV irradiation.However.for composed material HTiNbO5-Fe(OH)3and HNb3O8一Fe(OH)3. there has a strong adsorption ability of ethanethiol on its surface under visible light irra.diation.whieh can eventually be oxidized to sulfinic aeid(HO-SO).while under UV radiation.there is a new absorption peak in the IR spectrum which can be assigned to the absorption peak of sulfite.For HNb3O8-Fe2O3AND HTiNbO5-Fe2O3.there has adsorption abilitv of ethanethiol on its surface, which can be oxidized to sulfin acid and sulfite under visible light irradiation. The infrared spectra under the UV-visible radiation and visible light spectra were almost identical, which indicated that the composite catalytic material has a strong photocatalytie oxidation activity under visible radiation.A composite layered catalytic material can be prepared by an exfoliating-restacking technology, due to the effective electronic coupling between the host and the guest, the narrow band gap and the inhibition of the electron and hole. Therefore.it can absorb visible light and has a high quantum efficiency and exhibit enhanced catalytic activity.These porous composite materials shows high catalyticc activity in degradation of methylene blue under visible radiation and photocatalytic oxidation of ethanethiol.Different catalytic materials can be designed by altering different host and guest of material,the establishment of the semiconductor-semiconductor, so that specific reaction has high catalytic activity, which has laid a certain foundation for designing and fabricationing of catalyst.Figure:36table:5reference:71... |
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