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
运用 AES,XPS,XRD和 TEM等手段研究了 La Co O3模型催化剂 SO2 中毒过程表面化学状态、晶相结构及表面形貌的变化状况 ,初步推断了 La Co O3钙钛矿型复合金属氧化物催化剂的 SO2 中毒机理 .在 SO2强化中毒过程中 ,SO2 与催化剂的活性组...运用 AES,XPS,XRD和 TEM等手段研究了 La Co O3模型催化剂 SO2 中毒过程表面化学状态、晶相结构及表面形貌的变化状况 ,初步推断了 La Co O3钙钛矿型复合金属氧化物催化剂的 SO2 中毒机理 .在 SO2强化中毒过程中 ,SO2 与催化剂的活性组分 La Co O3反应生成硫酸镧和氧化亚钴 ,而在催化剂膜层内部则生成硫酸镧、亚硫酸镧及氧化亚钴 . SO2 对活性组分层的侵入及硫与 La Co O3活性组分的反应破坏了催化剂的钙钛矿结构 ,使得催化剂彻底中毒 .当中毒温度较低及中毒时间较短时 ,硫在膜层中呈峰形分布 ,其浓度随中毒温度及时间的增加而增加 .随中毒温度的升高及中毒时间的增长 ,由于亚硫酸盐的分解作用 ,S在活性层中的浓度反而降低 ,中毒深度则继续增加 .展开更多
Nanoporous anorthic-phase Sn3O4 nanosheets are successfully fabricated via a hydrothermal process without any additives. With the pH value of the precursor increasing from 2.0 to 11.8, the valence of the precursor cha...Nanoporous anorthic-phase Sn3O4 nanosheets are successfully fabricated via a hydrothermal process without any additives. With the pH value of the precursor increasing from 2.0 to 11.8, the valence of the precursor changes from mixed valence （the ratio of Sn2＋ to Sn4＋ is 2.7： 1） to pure bivalent, and the product transformed from Sn3O4 to SnO mesocrystals. When doping SbC13 to the alkaline precursor, the valence of the precursor shows mixed valence with the ratio of Sn2＋ to Sn4＋ being 2.6： I and Sn3O4 is synthesized after the hydrothermal process. The valence state of Sn species in the precursor is the key factor of the formation of Sn3O4. The synthesis mechanism is discussed and proposed. These experimental results expand the knowledge base that can be used to guide technological applications of intermediate tin oxide materials.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）.
文摘运用 AES,XPS,XRD和 TEM等手段研究了 La Co O3模型催化剂 SO2 中毒过程表面化学状态、晶相结构及表面形貌的变化状况 ,初步推断了 La Co O3钙钛矿型复合金属氧化物催化剂的 SO2 中毒机理 .在 SO2强化中毒过程中 ,SO2 与催化剂的活性组分 La Co O3反应生成硫酸镧和氧化亚钴 ,而在催化剂膜层内部则生成硫酸镧、亚硫酸镧及氧化亚钴 . SO2 对活性组分层的侵入及硫与 La Co O3活性组分的反应破坏了催化剂的钙钛矿结构 ,使得催化剂彻底中毒 .当中毒温度较低及中毒时间较短时 ,硫在膜层中呈峰形分布 ,其浓度随中毒温度及时间的增加而增加 .随中毒温度的升高及中毒时间的增长 ,由于亚硫酸盐的分解作用 ,S在活性层中的浓度反而降低 ,中毒深度则继续增加 .
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21377063,51102250,21203226,and 21205127)the Personnel Training Foundation of Quzhou University(Grant No.BSYJ201412)
文摘Nanoporous anorthic-phase Sn3O4 nanosheets are successfully fabricated via a hydrothermal process without any additives. With the pH value of the precursor increasing from 2.0 to 11.8, the valence of the precursor changes from mixed valence （the ratio of Sn2＋ to Sn4＋ is 2.7： 1） to pure bivalent, and the product transformed from Sn3O4 to SnO mesocrystals. When doping SbC13 to the alkaline precursor, the valence of the precursor shows mixed valence with the ratio of Sn2＋ to Sn4＋ being 2.6： I and Sn3O4 is synthesized after the hydrothermal process. The valence state of Sn species in the precursor is the key factor of the formation of Sn3O4. The synthesis mechanism is discussed and proposed. These experimental results expand the knowledge base that can be used to guide technological applications of intermediate tin oxide materials.
