Papers by Keyword: Photo-Reduction

Abstract: The present study involves preparation of Ag nanoparticles (Ag NPs) deposited on non-woven fabrics by a two-step method including the chemical precipitation of Ag₂O nanoparticles on the fabrics followed by in situ reducing of the precursor into Ag NPs by different reductive processes including chemical reduction, photo-reduction and dielectric barrier discharge (DBD) cold plasma treatment. The morphology as well as the antibacterial efficiency of the Ag NPs deposited on non-woven fabrics are also evaluated. The Ag NPs-modified fabrics prepared by DBD plasma treatment exhibit significant antibacterial properties against both Escherichia coli and Staphylococcus aureus, and accordingly have potential applications in the healthcare and medicine fields.

Abstract: Perfluorinated chemicals (PFCs) are anthropogenic contaminants which have prompted much concern regarding their environment persistence and bioaccumulation. The main sources of PFCs are from wastewater of fluorine chemical. Decomposition and defluorination of PFCs in wastewater by photo-induced hydrated electrons was well and firstly investigated in this paper. In this work the proposed method was tested to deal with PFCs containing wastewaters from a Teflon-manufacturing plant in Jiangsu Province, China. 95.5% of perfluorooctanoic acid (PFOA) was decomposed after 12 hours treatment and defluorination rate of PFCs could reach about 60%. PFCs were transformed into harmless fluoride, acetic acid and formic acid. It was suggested this system can efficiently decompose PFCs from fluorine chemical plant. In brief, this study demonstrates that the photo-reduction is a high efficient, energy-saving method which produced less-toxic products for PFCs removal, compared with activated carbon absorption and combustion.

Abstract: Owing to the defects of the fixed TiO2 photocatalysts, the research employed the approach of anodic oxidation to produce high efficiend S-TiO2/Ti ceramic film oxidized on the surface of titanium, in order to make the absorbable spectrum of light catalyst spread to the visible region and constrain the high recombination rate of electron-hole pairs during photoreaction. The surface appearance and the distribution of elements have been checked with scanning electron microscopy. The microcrystal structure of the films has been checked with XRD. The results showed that the main components of sulfur-doped catalyzer were rutile and anatase, meanwhile, the sulfur element distributing on the film was fairly uniform. Films of S-TiO2 photocatalysis reduction K2CrO4 revealed that with the amount of S-contained increased, the rate of reduction K2CrO4 decreased under ultraviolet light while that increased under visible light. It was found that the highest reduction rate of K2CrO4 was achieved through an optimal Na2S2O3 dosage of 0.6g/L in ceramic film prepared processes.

Abstract: Owing to the defects of the fixed TiO2 photocatalysts, the research employed the approach of anodic oxidation to produce high efficiend N-TiO2/Ti ceramic film oxidized on the surface of titanium, in order to make the absorbable spectrum of light catalyst spread to the visible region and constrain the high recombination rate of electron-hole pairs during photoreaction. The surface appearance and the distribution of elements have been checked with scanning electron microscopy and EPMA. The microcrystal structure of the films has been checked with XRD. The results showed that the main components of nitrogen-doped catalyzer were rutile and anatase, meanwhile, the nitrogen element distributing on the film was fairly uniform. Films of N-TiO2 photocatalysis reduction K2CrO4 revealed that with the amount of N-contained increased, the rate of reduction K2CrO4 decreased under ultraviolet light while that increased under visible light. It was found that the highest reduction rate of K2CrO4 was achieved through an optimal (NH4)2S2O8 dosage of 0.4g/L in ceramic film prepared processes.

Abstract: This study used a photo-reduction method to investigate cuprous oxide (Cu2O) self-assembled micro/nanostructures, and design a test specimen with an electron concentration gradient distribution. It also observed the Cu2O reduction of the self-assembled structure with respect to electron density. SEM analysis was adopted to analyze the growth mechanism and growth model. The results showed that, its structure size increased with photo-reduction time, and as the reduction solution concentration increased, its structure crystallinity declined. The basic unit of a self-assembled microstructure was Cu2O at a diameter of 10~15nm, then these particles conglomerate in self-assembly to form various kinds of Cu2O micro/nanostructures with respect to reduction electron density, and primarily presented in the form of a cone or cube. In the process of continuous self-assembly, there were many micro-defects under the perfect crystal surface. Considering the growth rate, the final growth surface of the structure was (111) or (100).

Abstract: Metal particles of silver (Ag) and copper (Cu) have been synthesized in the presence of Aerosol-OT (AOT) or fluorinated surfactants in water-in-scCO2 microemulsions by the chemical reduction of AgClO4 and Cu(ClO4)2. The formation of Ag particles by the photo-reduction using UV-light have been confirmed by in-situ UV-Vis, X-ray absorption fine structure (XAFS), and small angle X-ray scattering (SAXS) measurements. Cu particles have also been prepared by the addition of a reducing reagent sodium borohydride, and the electronic structure of Cu ionic species has been investigated after reduction in the water-in-scCO2 microemulsions. The average size of aggregates of Ag particles in the microemulsions by means of in-situ SAXS measurements also has been estimated.