Bi 2O 3 nanoparticles were prepared by means of ammonia precipitation, polyol mediated methods and microemulsion chemical method. The structure and properties of the as-prepared nanoparticles, having been submitted to...Bi 2O 3 nanoparticles were prepared by means of ammonia precipitation, polyol mediated methods and microemulsion chemical method. The structure and properties of the as-prepared nanoparticles, having been submitted to a heat-treatment test at 750 ℃, were characterized by means of XRD, BET, XPS and UV-Vis absorption techniques. The photocatalytic oxidation reactions of benzene, toluene and xylene were used as the model reaction to measure the photocatalytic activity of Bi 2O 3 nanoparticles, respectively. The results show that the crystallite size of Bi 2O 3 prepared with different methods and calcined at 750 ℃ were 50.6, 38.5 and 31.5 nm, respectively. The photocatalytic activity of Bi 2O 3 nanoparticles prepared with the microemulsion chemical method was higher than that of the particles prepared with the polyol mediated method; and that of the particles prepared with the micromulsion chemical method was the highest among the three. The degradation rates of the three pollutants xylene, toluene and benzene decreased in sequence.展开更多
Two kinds of TiO_2 nanometer thin films were prepared on stainless steel bythe reverse micellar and sol-gel methods, respectively. The calcined TiO_ 2 thin films werecharacterized by X-ray diffraction (XRD), atomic fo...Two kinds of TiO_2 nanometer thin films were prepared on stainless steel bythe reverse micellar and sol-gel methods, respectively. The calcined TiO_ 2 thin films werecharacterized by X-ray diffraction (XRD), atomic force microscopy (AFM), BET surface area and X-rayphotoelectron spectroscopy (XPS). Photocatalytic activity was evaluated by photocatalyticdecoloration of methyl orange aqueous solution. The results showed that the TiO_2 thin filmsprepared by reverse micellar method (designated as RM-TiO_2 films) showed higher photocatalyticactivity than those by sol-gel method (designated as SG-TiO_2 films). This is attributed to the factthat the former is composed of smaller monodispersed spherical particles with a size of about 15 nmand possesses higher surface areas.展开更多
A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(...A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...展开更多
The visible-light photocatalytic activity of BiFeO3 can be enhanced by treating in LiNO3 molten salt. BiFeO3 is prepared by pyrolysis of tartaric acid complex. The as-prepared BiFeO3 is mixed with LiNO3 salt by ball m...The visible-light photocatalytic activity of BiFeO3 can be enhanced by treating in LiNO3 molten salt. BiFeO3 is prepared by pyrolysis of tartaric acid complex. The as-prepared BiFeO3 is mixed with LiNO3 salt by ball milling for 4 h with the molar ratio 12∶1 of LiNO3 to BiFeO3. The mixture was heated at 270 ℃ for 12 h, and LiNO3 was removed from the product by washing with distilled water. The visible light photocatalytic activity is evaluated by measuring the decoloratation of Congo red aqueous solution. After heating in LiNO3 molten salt, the decoloratation of Congo red aqueous solutions increased significantly from 31.6% to 95.4%. The enhancement of the photocatalytic activity is attributed to surface modification of BiFeO3 by treating in LiNO3 molten Salt.展开更多
Nanometer perovskite-type oxides MgTiO3,CaTiO3,SrTiO3 were prepared using tetrabutyl titanate,alkaline earth metal nitrates as raw materials by sol-gel method.The samples were characterized by thermogravimetry-differe...Nanometer perovskite-type oxides MgTiO3,CaTiO3,SrTiO3 were prepared using tetrabutyl titanate,alkaline earth metal nitrates as raw materials by sol-gel method.The samples were characterized by thermogravimetry-differential thermal(TG-DTA),X-ray diffraction(XRD),UV-Vis spectrophotometer(UV-Vis)and X-ray photoelectron spectroscopy(XPS).Using methylene blue as a degradation target,we studied that calcination temperature had an impact on photocatalytic activity of three different photocatalysts.Through the photocatalytic degradation of methylene blue,photocatalytic activity of the three perovskite-type catalysts was compared.The results showed that different crystal structure resulted in different temperature of optimum activity.The temperature of best photocatalytic activity for MgTiO3 was 700 ℃,CaTiO3 and SrTiO3 were 800 ℃.In the above-mentioned catalyst,CaTiO3 had the highest photocatalytic activity.XPS analysis and catalytic reaction with O2 show that the surface oxygen absorbed capacity is the most important factor which has an influence on photocatalytic activity of three perovskite-type photocatalysts.展开更多
It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties...It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties of TiO_2 thin films. Therefore, it is necessary toelucidate the influence of the preparation process and post-treatment conditions on thephoto-catalytic activity and surface microstructures of the films. This review deals with thepreparation of TiO_2 thin film photo-catalysts by wet-chemical methods (such as sol-gel,-reversemicellar and liquid phase deposition) and the comparison of various preparation methods as well astheir advantage and disadvantage. Furthermore, it is discussed that the advancement ofphotocatalytic activity, super-hydrophilicity and bactericidal activity of TiO_2 thin filmphotocatalyst in recent years.展开更多
基金the National Natural Science Foundation of China(No.2 0 2 770 15 )
文摘Bi 2O 3 nanoparticles were prepared by means of ammonia precipitation, polyol mediated methods and microemulsion chemical method. The structure and properties of the as-prepared nanoparticles, having been submitted to a heat-treatment test at 750 ℃, were characterized by means of XRD, BET, XPS and UV-Vis absorption techniques. The photocatalytic oxidation reactions of benzene, toluene and xylene were used as the model reaction to measure the photocatalytic activity of Bi 2O 3 nanoparticles, respectively. The results show that the crystallite size of Bi 2O 3 prepared with different methods and calcined at 750 ℃ were 50.6, 38.5 and 31.5 nm, respectively. The photocatalytic activity of Bi 2O 3 nanoparticles prepared with the microemulsion chemical method was higher than that of the particles prepared with the polyol mediated method; and that of the particles prepared with the micromulsion chemical method was the highest among the three. The degradation rates of the three pollutants xylene, toluene and benzene decreased in sequence.
基金This project is financially supported by the National Natural Science Foundation of China (No.s 50272049, 50072016) The Excellent Young Teachers Program of MOE, China (No. (2002)350)
文摘Two kinds of TiO_2 nanometer thin films were prepared on stainless steel bythe reverse micellar and sol-gel methods, respectively. The calcined TiO_ 2 thin films werecharacterized by X-ray diffraction (XRD), atomic force microscopy (AFM), BET surface area and X-rayphotoelectron spectroscopy (XPS). Photocatalytic activity was evaluated by photocatalyticdecoloration of methyl orange aqueous solution. The results showed that the TiO_2 thin filmsprepared by reverse micellar method (designated as RM-TiO_2 films) showed higher photocatalyticactivity than those by sol-gel method (designated as SG-TiO_2 films). This is attributed to the factthat the former is composed of smaller monodispersed spherical particles with a size of about 15 nmand possesses higher surface areas.
基金supported by the Ministry of Science and Technology of Beijing (20081D0500500142)
文摘A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...
文摘The visible-light photocatalytic activity of BiFeO3 can be enhanced by treating in LiNO3 molten salt. BiFeO3 is prepared by pyrolysis of tartaric acid complex. The as-prepared BiFeO3 is mixed with LiNO3 salt by ball milling for 4 h with the molar ratio 12∶1 of LiNO3 to BiFeO3. The mixture was heated at 270 ℃ for 12 h, and LiNO3 was removed from the product by washing with distilled water. The visible light photocatalytic activity is evaluated by measuring the decoloratation of Congo red aqueous solution. After heating in LiNO3 molten salt, the decoloratation of Congo red aqueous solutions increased significantly from 31.6% to 95.4%. The enhancement of the photocatalytic activity is attributed to surface modification of BiFeO3 by treating in LiNO3 molten Salt.
文摘Nanometer perovskite-type oxides MgTiO3,CaTiO3,SrTiO3 were prepared using tetrabutyl titanate,alkaline earth metal nitrates as raw materials by sol-gel method.The samples were characterized by thermogravimetry-differential thermal(TG-DTA),X-ray diffraction(XRD),UV-Vis spectrophotometer(UV-Vis)and X-ray photoelectron spectroscopy(XPS).Using methylene blue as a degradation target,we studied that calcination temperature had an impact on photocatalytic activity of three different photocatalysts.Through the photocatalytic degradation of methylene blue,photocatalytic activity of the three perovskite-type catalysts was compared.The results showed that different crystal structure resulted in different temperature of optimum activity.The temperature of best photocatalytic activity for MgTiO3 was 700 ℃,CaTiO3 and SrTiO3 were 800 ℃.In the above-mentioned catalyst,CaTiO3 had the highest photocatalytic activity.XPS analysis and catalytic reaction with O2 show that the surface oxygen absorbed capacity is the most important factor which has an influence on photocatalytic activity of three perovskite-type photocatalysts.
文摘It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties of TiO_2 thin films. Therefore, it is necessary toelucidate the influence of the preparation process and post-treatment conditions on thephoto-catalytic activity and surface microstructures of the films. This review deals with thepreparation of TiO_2 thin film photo-catalysts by wet-chemical methods (such as sol-gel,-reversemicellar and liquid phase deposition) and the comparison of various preparation methods as well astheir advantage and disadvantage. Furthermore, it is discussed that the advancement ofphotocatalytic activity, super-hydrophilicity and bactericidal activity of TiO_2 thin filmphotocatalyst in recent years.
