Papers by Keyword: Visible Light Activity

Abstract: Due to its excellent physical properties and inert chemical reaction activity of C₆₀, it is possible to synthesize solution-processing polymer containing C₆₀ utilizing the inclusive characteristics of polymer chain segment, and then to prepare organic/inorganic nanocomposites with enhanced some key properties. In order to harvest the visible light of TiO₂ effectively the surface modification of TiO₂ nanotube with polymer containing C₆₀ was carried out in this study. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), Fourier-Transform Infrared (FTIR) spectra, UV-Vis (Ultra-violet visible spectroscopy), XRD patterns analysis. The results showed that the UV-Vis of resulting nanocomposite was almost covered the whole region of visible light. The photoconductivity response to visible light with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The results indicated that the photoresponses of two kinds of polymer containing C₆₀ to weak visible light emerged photo-switching behavior, its recoverability was also rapidly, and the photoresponse of TiO₂ nanotube modified with two kinds of polymer containing C₆₀ to weak visible light also changed greatly. This illustrated that the organic-inorganic nanocomposites showed good activities to weak visible light. Photocatalytic efficiency was examined by selecting typical organic pollutants, some good results were obtained. It may develop organic-inorganic nanocomposites with external stimuli response, photocatalyst, et al.

Abstract: To make full use of the visible light more effectively, many studies are focuses on ZnO baesd nanocomposites. To modify the surface of ZnO with functional polymer is a very simple and effective approach. PVK (N-vinyl carbazole polymer) is one of typical organic functional materials, which is generally used as charge transfer materials for the applications of several organic electronic devices. Surface modification of ZnO nanosheets with polymer containing –COOH and N-vinyl carbazole group was performed with self-assembly process for improving the adsorption to visible light and properties of charge transfer in nanoscale. A series of characterizations were carried out by SEM (scanning electron microscopy), Fourier-Transform Infrared (FTIR) spectra, UV-Vis (Ultra-violet visible spectroscopy), et al. The adsorption of the nanocomposite was extended to the region of visible light. The photoconductivity response to weak visible light was studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The photocurrent of ZnO nanosheets modified with the polymer containing N-vinyl carbazole to weak visible light was changed greatly. The organic-inorganic nanocomposite showed good activities to visible light, with which it can be easily produced photo-induced charges, avoiding the recombination of charges produced by visible light. Photocatalytic efficiency was examined by selecting typical organic pollutants and some good results were obtained, showing much prospect in the fields of photocatalysts, nanoreactors, self-cleaning films, coatings, and organic pollutants treatment of environmental.

Abstract: Regarding catalytic and plasmonic properties of gold nanoparticles (NPs), the novel area of research on photocatalytic gold properties has been recently started. In contrast with catalytically active gold NPs, where nanosized gold is recommended, our results showed that polydispersity of deposited gold NPs on semiconducting support was beneficial for photocatalytic activity under visible light irradiation. It is thought that wide size/shape distribution of gold NPs, and thus the ability of absorption of light in a wide wavelengths range is responsible for the high level of photoactivity. Though desirable absorption properties of plasmonic photocatalysts can be easily obtained by preparation of nanoparticles of different sizes and shapes, their photocatalytic activities under visible light irradiation are still low and should be enanced. The improvement of photocatalytic activities under visible light irradiation was achieved by enlargement of interfacial contact between titania and NPs of noble metals, extension of photoabsorption ranges (by preparation of NPs of various sizes and shapes or composed of two kinds of noble metals), and by deposition of noble metals NPs on faceted titania, i.e., octahedral (OAPs) and decahedral (DAPs). Plasmonic photocatalysts composed of titania and NPs of silver, gold or copper showed also high antiseptic properties under visible light irradiation, due to possible synergism of antiseptic properties of noble metals and photodisinfection properties of photocatalyst, since reactive oxygen species or photogenerated holes are formed on the surface of irradiated semiconductor.

Abstract: A visible-light-driven photocatalyst Ag3PO4 was prepared by a novel precipitation- replacement process. The synthesized sample was cubic crystals with the bandgap of 2.16 eV. And most of the particles size was among 0.5~2 mm. The Ag3PO4 shows high photocatalytic activity for the degradation of methyl orange (MO) solution under the visible light (l>420 nm). The apparent ratio constant (kapp) value of Ag3PO4 was about 239 and 50 times that of P25 and C-TiO2, respectively.

Abstract: A novel visible-light-active C-N-Cl-codoped TiO2 photocatalyst was prepared by a simple process. The as-prepared sample was characterized by XRD, XPS, and UV-Vis. The analysis results showed that the as-synthesized sample was anatase and possessed a narrow bad gap of 2.4 eV after the doping of carbon, nitrogen and chlorine. An obvious absorption for visible light was observed in the range of 400~700 nm for C-N-Cl-codoped TiO2. By degrading of methyl orange (MO) solution under the visible light (l>420 nm) irradiation, the synthesized photocatalyst showed 5 times photocatalytic activity than that of P25.

Abstract: A new visible-light-driven plasmonic photocatalyst Ag/AgCl/TiO_2-XC_X was prepared by a two-step synthesis process. The bandgap of the synthesized sample was 2.87 eV. In the degradation of methyl orange (MO) solution under the visible light (l>420 nm), the Ag/AgCl/TiO_2-X C_X shows higher photocatalytic activity than TiO_2-X C _X . The apparent ratio constant (kapp) value of Ag/AgCl/TiO_2-XC_X was about 9.7 times that TiO_2-XC_X.

Abstract: A magnetically separable photocatalyst silver vanadates@SiO₂/Fe₃O₄ was prepared by hydrothermal process. The prepared sample was composed of mixed phases of a–Ag₃VO₄ and Ag₄V₂O₄, and the main phase was a–Ag₃VO₄. The bandgap of the synthesized sample was 2.2 eV. In the degradation of methyl orange (MO) solution under the visible light (l>420 nm), the silver vanadates@SiO₂/Fe₃O₄ showed high photocatalytic activity in two-cycle photocatalytic test.

Abstract: A visible-light-active C-doped TiO₂ photocatalyst was prepared by a simple wet process. The XPS analysis results showed that carbon was doped into TiO₂ particles and one kind of carbonate species with Ti-O-C structure was formed. The obtained sample showed obvious absorption in the 400-800 nm range in UV-vis spectra. By degrading of methyl orange (MO) solution under visible light irradiation (l>420 nm), the apparent rate constant (k_app) of S170 was about 10 times larger than that of P25. The preparation procedure of such C-doped catalyst can be easily scaled up for industrial production due to its simplicity.

Abstract: TiO₂ photocatalyst modified with N and Fe (Fe-TiO_2-xN_x) was obtained. Bimetal and nitrogen co-modified TiO₂ (Ag/Fe-TiO_2-xN_x) was prepared by photo catalytic reduction of Ag on the Fe and nitrogen co-modified TiO₂. The catalytic activity of sample for photocatalytic reduction of nitrate under visible light was tested. And the bimetal and nitrogen co-modified TiO₂ was characterized by XRD, XPS, TEM and UV-vis diffuse reflectance spectrophotometry.

Abstract: Carbon doped titanium dioxide photocatalysts have been synthesized by a precipitation method. Anatase TiO2 was obtained when the precipitate was heat-treated at 400°C when rutile phase appeared at 600°C. The absorption spectra of the powders showed strong absorption in visible region. For the sample calcined at 400 °C , the absorption extended up to 750nm. X-ray photoelectron spectrum (XPS) confirmed that carbon atoms were incorporated into the TiO2 crystal lattice. Photodegradation experiments showed that the powders had visible-light degradation activity.