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
A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid...A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peaks by 230 mV. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine and ascorbic acid can be determined simultaneously with the modified electrode. The electrode shows good sensitivity, selectivity and stability.展开更多
Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology o...Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology of ITO precursors and ITO nanopowders were studied by X-ray diffractometry,transmission electron microscopy and differential thermal and thermogravimetry analysis methods.The TG-DSC curves show that the decomposition process of precursor precipitation is completed when the temperature is close to 600 ℃and the end temperature of decompositionis somewhat lower when the doping amount of SnO2 is increased.The XRD patterns indicate that the solubility limit of Sn4+ relates directly to the calcining temperature. When being calcined at 700℃,a single phase ITO powder with 15%SnO2(mass fraction)can be obtained.But,when the calcining temperature is higher than 800℃,the phase of SnO2 will appear in ITO nanopowders which contain more than 10%SnO2.The particle size of the ITO nanopowders is 15-25 nm.The ITO nanoparticles without Sn have a spherical shape,but their morphology moves towards an irregular shape when being doped with Sn4+.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A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peaks by 230 mV. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine and ascorbic acid can be determined simultaneously with the modified electrode. The electrode shows good sensitivity, selectivity and stability.
基金Project(U0837604)supported by the Natural Science Foundation of Yunnan Province,ChinaProject(07C40291)supported by Research Fund of Yunnan Education Department,ChinaProject(2007003)supported by Research Fund of Kunming University of Science and Technology,China
文摘Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology of ITO precursors and ITO nanopowders were studied by X-ray diffractometry,transmission electron microscopy and differential thermal and thermogravimetry analysis methods.The TG-DSC curves show that the decomposition process of precursor precipitation is completed when the temperature is close to 600 ℃and the end temperature of decompositionis somewhat lower when the doping amount of SnO2 is increased.The XRD patterns indicate that the solubility limit of Sn4+ relates directly to the calcining temperature. When being calcined at 700℃,a single phase ITO powder with 15%SnO2(mass fraction)can be obtained.But,when the calcining temperature is higher than 800℃,the phase of SnO2 will appear in ITO nanopowders which contain more than 10%SnO2.The particle size of the ITO nanopowders is 15-25 nm.The ITO nanoparticles without Sn have a spherical shape,but their morphology moves towards an irregular shape when being doped with Sn4+.
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.
