SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and so...SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and sol-gel method. The XRD, TEM and FTIR results show that a new kind of active particle (Ti, Sn)O2 has formed and there is no sign of SnO2 crystals observed in the range of the doping concentration studied. The samples’ photocatalytic activity was evaluated by the degradation of acrylic acid. The results indicate that the SnO2/TiO2 nano- composite photocatalysts prepared through SCFCT show significant improvement in catalytic activity as compared to pure TiO2 or SnO2/TiO2 catalysts pre- pared by traditional drying (TD). The effect of H2O2 (0.167 v%) on the photodegradation was also inves- tigated. After the addition of H2O2, the chemical oxy- gen demand (COD) of acrylic acid, which had been treated with (15.1 mol%) SnO2/TiO2 nanocomposite photocatalysts for 3 h, was reduced from 400―500 to 20 mg/L.展开更多
Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, cr...Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, crystal structure and ther- mal behavior of silver behenate nanocrystals were investigated using SEM, TEM, XRD, IR and TG-DTA. These results showed that the preparation method, reaction temperature and excessive silver ion con- centration in reaction solution played important roles in determining the size of silver behenate nanocrys- tals. The prepared silver behenates were scaly crys- tals with a mean diameter of about 70 nm. The silver behenate nanocrystals possessed layer structure. A series of structural changes of silver behenate nanocrystals were observed at different temperatures. The silver behenate nanocrystals had excellent thermal stability below 120℃. At high temperature there were two distinct transitions resulting in dra- matic structural changes. In the first transition at 138℃, the alkyl chains of silver behenate were trans- formed from an ordered into a disordered state. In the second transition at 230℃, a completely irreversible structural change took place due to the decomposi- tion of silver behenate nanocrystals.展开更多
基金This work was supported by the National Natural Science Foundation of China （Grant No. 20076004） the Research Fund for the Doctoral Programof Higher Education （Grant No. 20050010014）.
文摘SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and sol-gel method. The XRD, TEM and FTIR results show that a new kind of active particle (Ti, Sn)O2 has formed and there is no sign of SnO2 crystals observed in the range of the doping concentration studied. The samples’ photocatalytic activity was evaluated by the degradation of acrylic acid. The results indicate that the SnO2/TiO2 nano- composite photocatalysts prepared through SCFCT show significant improvement in catalytic activity as compared to pure TiO2 or SnO2/TiO2 catalysts pre- pared by traditional drying (TD). The effect of H2O2 (0.167 v%) on the photodegradation was also inves- tigated. After the addition of H2O2, the chemical oxy- gen demand (COD) of acrylic acid, which had been treated with (15.1 mol%) SnO2/TiO2 nanocomposite photocatalysts for 3 h, was reduced from 400―500 to 20 mg/L.
文摘Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, crystal structure and ther- mal behavior of silver behenate nanocrystals were investigated using SEM, TEM, XRD, IR and TG-DTA. These results showed that the preparation method, reaction temperature and excessive silver ion con- centration in reaction solution played important roles in determining the size of silver behenate nanocrys- tals. The prepared silver behenates were scaly crys- tals with a mean diameter of about 70 nm. The silver behenate nanocrystals possessed layer structure. A series of structural changes of silver behenate nanocrystals were observed at different temperatures. The silver behenate nanocrystals had excellent thermal stability below 120℃. At high temperature there were two distinct transitions resulting in dra- matic structural changes. In the first transition at 138℃, the alkyl chains of silver behenate were trans- formed from an ordered into a disordered state. In the second transition at 230℃, a completely irreversible structural change took place due to the decomposi- tion of silver behenate nanocrystals.
