SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surfa...SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.展开更多
SnO 2 powder was prepared by chemical precipitation method. Effects of starting materials concentration, pH value of final system and treating temperature on the particle size were investigated by means of X-ray diffr...SnO 2 powder was prepared by chemical precipitation method. Effects of starting materials concentration, pH value of final system and treating temperature on the particle size were investigated by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The parameters of chemical precipitation were optimized. It is concluded that the concentration of starting material and pH value of final system has little effect on the SnO 2 particle size, but heat treatment do greatly affect the particle size. If the treating temperature is lower than 500 ℃, the particle size has a good stability; otherwise, the particle size remarkably increases with increasing temperature. The dispersing agents have various influences on SnO 2 powder as the polarity of dispersing agents changed.展开更多
Nanosized SnO 2 powders were synthesized by using the direct pyrolysis means from SnC 2O 4 .The specimens were characterized by TEM, XRD, TG-DTA, FTIR and BET. TEM and XRD showed that the SnO 2 crystallines were less ...Nanosized SnO 2 powders were synthesized by using the direct pyrolysis means from SnC 2O 4 .The specimens were characterized by TEM, XRD, TG-DTA, FTIR and BET. TEM and XRD showed that the SnO 2 crystallines were less than 8 nm in diameter together with a narrow particle size distribution. BET showed that the surface area of SnO 2 was 115.2 m 2/g. FTIR spectra revealed that the absorptions of Sn—O and —OH bonds in SnO 2 ultrafine powders were red-shifted and broadened. According to the curve of TG-DTA, SnC 2O 4 transformed into SnO 2 completely after being calcined at 250 ℃. Further gas sensing experiments testified that the response and recovery times to C 2H 5OH were shorter than those obtained by the conventional precipitation method.展开更多
Preparing SnO2 with hierarchical micro/nano structures by hydrothermal, coordination, templating and electrochemical deposition methods and their mechanisms are investigated. The result shows that the echinus-like SnO...Preparing SnO2 with hierarchical micro/nano structures by hydrothermal, coordination, templating and electrochemical deposition methods and their mechanisms are investigated. The result shows that the echinus-like SnO2 prepared by Method 1 is a typical Ostwald mechanism that develops from internally to externally. The cabbage-like SnO2 by Method 2 is produced with oxalic acid as complexing agent to set-up precursor of SnO2, and then precursors are bocked around the body that is around the body being bocked. The nest-like SnO2 by Method 3 is controlled by citric acid as coordinator for the nucleation as well as the grow rate and setup process. Spongy-like SnO2 by Method 4 is produced using PST as template, PST is be infiltered into SnO2 precursor by gravity and capillary and treated thermally to form a multiporous structure. The petal-like SnO2 by Method 5 is formed with crystal deposition emergence due to oxidation-reduction reactions of two electrodes in an electric field. XRD analyses shows that the five results are all pure phase SnO2. It provides basic data for SnOE industrial application.展开更多
基金Projects(60806032,20975107) supported by the National Natural Science Foundation of ChinaProject(2009R10064) supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Education Ministry,China+2 种基金 Project(2009R10064) supported by "Qianjiang Talent Program"Projects(2009A610058,2009A610030) supported by the Ningbo Natural Science Foundation,ChinaProject supported by K.C.WONG Magna Fund in Ningbo University,China
文摘SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.
文摘SnO 2 powder was prepared by chemical precipitation method. Effects of starting materials concentration, pH value of final system and treating temperature on the particle size were investigated by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The parameters of chemical precipitation were optimized. It is concluded that the concentration of starting material and pH value of final system has little effect on the SnO 2 particle size, but heat treatment do greatly affect the particle size. If the treating temperature is lower than 500 ℃, the particle size has a good stability; otherwise, the particle size remarkably increases with increasing temperature. The dispersing agents have various influences on SnO 2 powder as the polarity of dispersing agents changed.
文摘Nanosized SnO 2 powders were synthesized by using the direct pyrolysis means from SnC 2O 4 .The specimens were characterized by TEM, XRD, TG-DTA, FTIR and BET. TEM and XRD showed that the SnO 2 crystallines were less than 8 nm in diameter together with a narrow particle size distribution. BET showed that the surface area of SnO 2 was 115.2 m 2/g. FTIR spectra revealed that the absorptions of Sn—O and —OH bonds in SnO 2 ultrafine powders were red-shifted and broadened. According to the curve of TG-DTA, SnC 2O 4 transformed into SnO 2 completely after being calcined at 250 ℃. Further gas sensing experiments testified that the response and recovery times to C 2H 5OH were shorter than those obtained by the conventional precipitation method.
基金Supported by fund of the Excellent Science&Technology Innovate Team Program for Young and Middle-aged Talents in University of Hubei Province(T201225)Hubei Provincial Key Laboratory of Plant Anti-Cancer Active Substance Purification and Application,The Second Excellent Teacher Team of Hubei University of Education(2012K203)
文摘Preparing SnO2 with hierarchical micro/nano structures by hydrothermal, coordination, templating and electrochemical deposition methods and their mechanisms are investigated. The result shows that the echinus-like SnO2 prepared by Method 1 is a typical Ostwald mechanism that develops from internally to externally. The cabbage-like SnO2 by Method 2 is produced with oxalic acid as complexing agent to set-up precursor of SnO2, and then precursors are bocked around the body that is around the body being bocked. The nest-like SnO2 by Method 3 is controlled by citric acid as coordinator for the nucleation as well as the grow rate and setup process. Spongy-like SnO2 by Method 4 is produced using PST as template, PST is be infiltered into SnO2 precursor by gravity and capillary and treated thermally to form a multiporous structure. The petal-like SnO2 by Method 5 is formed with crystal deposition emergence due to oxidation-reduction reactions of two electrodes in an electric field. XRD analyses shows that the five results are all pure phase SnO2. It provides basic data for SnOE industrial application.
