Summary: A controlled fabrication of rod‐like nanostructures of cadmium sulfide (CdS) incorporated into polymer fiber matrices has been developed by an electrospinning method. Here, poly(vinyl pyrrolidone) (PVP) was used as a polymer capping reagent, utilizing the interactions of cadmium ions with the carbonyl groups in the PVP molecules. The formation of CdS nanorods inside the PVP was carried out via the reaction of Cd2+ with H2S. SEM images showed that the electrospun films of PVP/CdS are composed of fibers with a diameter between 100 and 900 nm. TEM proved that most of the CdS nanorods are incorporated in the PVP fibrous film. The diameter of the rod is about 50 nm and the length is from 100 to 300 nm.
TEM image of the CdS nanorods formed in the PVP fibrous film. 相似文献
The inorganic ion-exchanger α-zirconium phosphate was synthesized by the sol-gel method and its properties relating to the exchange of Cd2+ and the intercalation of CdS particles were studied. The Cd2+-exchange process is a fast process and the material obtained exhibits an increased interlayer distance d with respect to its precursor (9.56 vs. 7.56 Å). The resulting Cd-containing material was exposed to aH2S gas flow to give CdS particles in the exchanger. The zirconium phosphate containing CdS particles still possesses a layered structure, with a pattern almost identical to that of the initial ion-exchanger precursor. Moreover, the material may exchange further Cd2+ and hence lead to a higher CdS particle content. The thermal behavior of this ion-exchangers containing Cd2+ or CdS particles was studied. 相似文献
TiO2 nano particles with photo catalytic property were mixed with silica alkoxides solution with HAuCl4/4H2O. STS02 (purchased from Ishihara Sangyo Kaisha, Ltd.) was used as TiO2 nano particles. The average size of TiO2 nano particles was 7 nm in diameter. The gel film coated on glass substrate was heated and then HAuCl4/4H2O was thermally reduced at 390 degree. The coated silica gel film doped with HAuCl4/4H2O and TiO2 nano particles was turned into light blue from colorless gel film after heat treatment. The optical absorption spectrum showed the absorption peak of the film heated at 390 degree shifted to at about 650 nm compare to SiO2 film doped with Au nano particles without TiO2 nano particles that had absorption peak at 542 nm. On the other hand, the film formed from coating solution incorporated TiAA (titanium tetraisopropoxide chelated by acetyl acetone) as TiO2 source instead of TiO2 nano particles had absorption peak at 550 nm. That means there was no effect on formation of Au nano particles when TiAA was incorporated. The average size of the particles was found to be about 23 nm in diameter by TEM observation. Furthermore EDX (Energy Dispersive X-ray Fluorescence Spectrometer) analysis of nano particles in the film indicated that Au-TiO2 nano hybrid particles were formed. Simulation results also supported that the size in diameter of Au nano particles had little influence on the absorption coefficient of the silica film doped with Au nano particles. 相似文献
Hollow hybrid nanostructures have received significant attention because of their unique structural features. This study reports a facile ion adsorption–heating method to fabricate hollow PbS‐TiO2 hybrid particles. In this method, the TiO2 spheres used as a substrate material to grow PbS are aggregates of many small amorphous TiO2 particles, and each small particle is covered with thioglycolic acid ligands through Ti4+–carboxyl coordination. When Pb2+ ions are added to a colloidal solution of these TiO2 spheres, these ions are adsorbed by sulfhydryl (‐SH) groups to form metal thiolates, and the C−S bond is dissociated by heating to release S2−. The S2− ions react with Pb2+ ions to form PbS without additive sulfur sources. Additionally, the amorphous TiO2 spheres are transformed into the anatase phase during the heating process. As a result, the crystallization of TiO2 spheres along with the formation of PbS is simultaneously carried out by heating. During the heating process, owing to the Kirkendall effect of S2− diffusion and the Ostwald ripening effect of the crystallization of amorphous TiO2 spheres, PbS‐TiO2 hollow hybrid structures can be obtained. The XRD and XPS characterizations proved the formation of anatase TiO2 and PbS. The TEM characterization confirmed the formation of hollow structures in the PbS‐TiO2 hybrid sample. The photocatalytic activity of the hollow PbS‐TiO2 hybrid spheres have been investigated for the degradation of Cr6+ under visible light. The results show that hollow PbS‐TiO2 hybrid spheres exhibited the highest photocatalytic activity, in which almost all the Cr6+ was degraded after 140 min. 相似文献
This article presents a facile method to prepare CdS/SiO2 composite microspheres and their good catalytic properties. In our method, monodispersed SiO2 particles bearing amino groups (–NH2) were synthesized at first and then used as carriers to load nanosized CdS particles to form CdS/SiO2 composite microspheres. With the addition of CdAc2 solution to the SiO2 dispersion, Cd2+ was attracted to the surfaces of the SiO2 particles through coordination interaction, and then thioacetamide was added to the dispersion. By heating, S2? released and reacted with the Cd2+, CdS/SiO2 composite microspheres were obtained accordingly. The photocatalytic properties of the as‐prepared composite microspheres were investigated as well. It was found that the composite microspheres have excellent photocatalytic activities for the degradation of dyes comparing with the commercial P‐25 TiO2 catalysts. After using and recycling for three times, the photocatalytic performance still remained very well. 相似文献
A novel sol-gel process has been developed to prepare nano-sized CdS quantum dots to improve the nonlinear optical properties. A bifunctional ligand, 3-aminopropyl triethoxysilane H2N(CH2)3Si(OC2H5)3, was used to disperse the Cd2+ ions in the gel solution. The CdO and CdS particles were observed by transmission electron microscope (TEM). The size of CdS microcrystallites with concentrations up to 13 wt.% in SiO2 gel matrix was found to be in the range of 2–4 nm with a very sharp size distribution. A well-defined absorption edge was observed in the absorption spectrum. 相似文献
Silica hydrogels and planar substrates were patterned with CdS nanoparticles using a photolithographic method based on the
photo dissociation of thiols and cadmium-thiolate complexes. Silica hydrogels were prepared via a standard base-catalyzed
route. The solvent was exchanged with an aqueous solution of CdSO4 and 2-mercaptoethanol, and the samples were then exposed to a focused ultraviolet beam. Planar substrates were patterned
by illuminating a precursor solution spin coated on the substrates. CdS nanoparticles formed in the illuminated spots, and
had a diameter below about 2 nm. The diameter of the spots illuminated by the UV beam could be varied from a few hundred to
a few μm, on both hydrogels and planar substrates. Samples were characterized with transmission electron microscopy, X-ray
photoelectron spectroscopy, X-ray diffraction, and optical absorption, photoluminescence and Raman spectroscopies. All these
techniques confirmed the chemical identity of the CdS nanoparticles. To investigate the mechanism of nanoparticle formation,
we took absorption spectra of the precursor solution as a function of irradiation time. In unirradiated solutions, we noticed
a maximum at 250 nm, characteristic of Cd-thiolate complexes. The absorption at 250 nm decreased with increasing irradiation
time. A new band appeared at 265 nm for exposures around 5 min, and that band shifted to 290 nm in samples exposed for 10 min.
A yellow precipitate formed after about 30 min. XRD showed that the precipitate was cubic CdS, with a mean particle size of
1.4 nm. We attribute formation of CdS to the photodissociation of the thiols and of the Cd-thiolates. UV irradiation of these
precursors yields a series of species that can react with Cd2+, such as RS·, S2− and H2S. Small CdS nanoparticles form in the initial stages of illumination, and present absorption bands in the 265–290 nm region.
These CdS aggregates grow, coalesce and precipitate for longer irradiation times. 相似文献
Abstract A novel approach to assemble an H2O2 amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H2O2. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol?1 cm?2 for H2O2 over a wide linear range of concentration from 1.22×10?5 to 1.46×10?3 mol L?1, rapid response of <5 s and a detection limit of 0.61×10?6 mol L?1. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L?1 Tris‐HCl buffer solutions at pH 7. 相似文献