Zn掺杂的LaFeO_3纳米晶的制备及其光催化活性研究

以氧化镧、硝酸铁和硝酸锌为原料,用柠檬酸络合法制备了La1-xZnxFeO3(x=0,0.1,0.3,0.5,0.7)纳米光催化剂,对其进行了XRD,TEM,UV-vis,IR等测试,并研究了其对水溶性染料活性艳红X-3B的光催化活性。结果表明:制得的LaFeO3为钙钛矿型结构,Zn2+的少量掺杂不改变LaFeO3的钙钛矿型结构,当x=0.3时开始出现尖晶石型ZnFe2O4相,当x=0.5时光催化活性最好,x=0.7时钙钛矿的结构被破坏。适量的Zn2+掺杂可以提高LaFeO3的光催化活性。     

钙钛矿型LaFe1-xCuxO3的光催化活性研究

用柠檬酸络合法制备了钙钛矿型LaFeO3及LaFe1-xCuxO3化合物，测定了其对酸性红3B等水溶性染料的光催化降解活性。利用红外、紫外和光声光谱、正电子寿命谱及光电子能谱等技术分析了LaFeO3的光催化性能及掺杂对其活性的影响。结果表明，掺杂Cu^2 可使LaFeO3的光催化活性明显提高。     

LaFe1-xCuxO3光催化降解水溶性染料的活性

采用柠檬酸法合成了钙钛矿型复合氧化物催化剂LaFeO3,并按不同比例进行掺杂,制备了LaFe1-xCuxO3(x=0.01～0.09)系列样品.以高压荧光汞灯为光源,测定了该系列样品对酸性红3B等水溶性染料的光催化降解活性.采用红外、紫外、光声光谱及正电子寿命谱等技术分析了催化剂的光催化性能及掺杂对活性的影响.结果表明,掺杂后LaFeO3的光催化活性明显提高,这主要与B离子的d电子结构有关.     

La_(1-x)Sr_xFeO_3光催化降解水溶性染料

用柠檬酸法合成了钙钛矿型复合氧化物 La Fe O3,并按不同比例进行掺杂 ,制备了L a1-x Srx Fe O3( x=0 .0 1、0 .0 2、0 .0 3、0 .0 4、0 .0 5) .以荧光汞灯为光源测定了样品对不同染料的光催化降解活性 ,根据红外、紫外、光声光谱等技术对催化剂的分析结果 ,讨论了光催化性能及掺杂Sr2 对其活性的影响 ,结果表明 ,掺杂后 L a Fe O3的光催化活性明显提高     

B位掺杂GdCo1-xSrxO3的制备及其光催化活性

用柠檬酸络合法制备了钙钛矿型GdCo1-XSrXO3(X=0.00, 0.02, 0.04, 0.06, 0.08)复合氧化物, 通过XRD, TEM 等手段对所生成纳米晶的物相结构、微观形貌、颗粒大小等进行了表征. 结果表明, 所合成的颗粒为钙钛矿型纳米晶, 球形. 通过其对活性艳红 X-3B 降解对其光催化活性进行了研究, 实验结果表明在B 位掺杂 Sr2+ 后使GdCoO3 的光催化活性明显提高, 当X=0.06 时, 即GdCo0.94Sr0.06O3 的光催化活性最佳.     

钙钛矿型LaFeO3纳米材料光催化氧化NO2-的研究

采用有机前驱体法合成了钙钛矿型复合氧化物LaFeO3纳米物质,并用XRD,IR和TEM等对其进行了表征;结果表明,所制LaFeO3是立方体型,平均粒径在40~50 nm。以NO2-为目标降解物,考察其光催化活性,表明钙钛矿型复合氧化物LaFeO3纳米材料对NO2-的降解具有很好的催化效果。     

钙钛矿型A位掺杂复合氧化物La1-xSrxCoO3-6的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型La1-xSrxCoO3-6复合氧化物，用XRD、XPS、EDS、红外、紫外等技术进行了表征，测定了其对活性艳红等水溶性染料光催化脱色的活性．结果表明：在A位掺Sr^2＋，由于产生较多氧空位，表面非晶格活性氧量增加，使LaCoO3的光催化活性明显提高，其中La1-xSrxCoO3-6效果最佳．     

钙钛矿型A位掺杂复合氧化物La1-xSrxCoO3-δ的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型La1-xSrxCoO3-δ复合氧化物,用XRD、XPS、EDS、红外、紫外等技术进行了表征,测定了其对活性艳红等水溶性染料光催化脱色的活性.结果表明:在A位掺Sr2+,由于产生较多氧空位,表面非晶格活性氧量增加,使LaCoO3的光催化活性明显提高,其中Ia0.9Sr0.1CoO3-δ效果最佳.     

钙钛矿结构B位掺杂化合物LaCO1-xFexO3的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型LaCo1-xFexO3系列化合物，使用XRD、XPS、红外和紫外等手段对其进行了表征和测定，并测定了其对活性艳红水溶性染料脱色的光催化活性．实验结果表明在B位掺杂Fea 后使LaCoO3光催化活性明显提高，当x=0．05时，即LaCo1-xFexO3的光催化活性最佳。     

LaFe1-xCuxO3的光催化性及正电子湮没研究

研究LaFeO3及微量掺铜LaFeO3的光催化活性,利用正电子湮没谱分析掺杂的影响,发现随着掺杂百分比的增加,正电子寿命逐渐下降达到一最小值,然后又上升;而光催化活性随掺杂百分比的增加逐渐上升达到最大值,然后下降。结果表明：LaFeO3掺杂后光催化活性得以提高;正电子湮没技术是研究点阵缺陷结构的有效方法之一。     

纳米晶La_（1－_x）Sr_xFeO_3的合成及气敏特性的研究

用柠檬酸盐法合成出Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３（ｘ＝０．１，０．２，０．３，０．４）原粉，再经固相反应得到纳米晶粉末，用ＴＧ、ＤＴＡ、ＸＲＤ、ＩＲ进行了表征，确证复合氧化物Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３为钙钛矿型结构，粒径在１０～２５ｎｍ之间。实验结果表明，随着固相反应条件不同，产物粒径呈规律性变化．气敏特性研究表明，该纳米晶材料对乙醇有较高的选择性和灵敏度，其选择性顺序为Ｌａ_（０．９）Ｓｒ_（０．１）ＦｅＯ_３＞ＬａＦｅＯ_３＞ＬａＦｅＯ_３（大晶粒）。     

Impurity diffusion of (141)Pr in LaMnO(3), LaCoO(3) and LaFeO(3) materials

The impurity diffusion of Pr(3+) in dense polycrystalline LaMnO(3), LaCoO(3) and LaFeO(3) was studied at 1373-1673 K in air in order to investigate cation diffusion in these materials. Cation distribution profiles were measured by secondary-ion mass spectrometry and it was found that penetration profiles of Pr(3+) had two distinct regions with different slopes. The first, shallow region was used to evaluate the bulk diffusion coefficients. The activation energies for bulk diffusion of Pr(3+) in LaMnO(3), LaCoO(3) and LaFeO(3) were 126 +/- 6, 334 +/- 68 and 258 +/- 75 kJ mol(-1), respectively, which are significantly lower than previously predicted by atomistic simulations. The bulk diffusion of Pr(3+) in LaMnO(3) was enhanced compared to LaCoO(3) and LaFeO(3) due to higher concentrations of intrinsic point defects in LaMnO(3), especially La site vacancies. Grain-boundary diffusion coefficients of Pr(3+) in LaCoO(3) and LaFeO(3) materials were evaluated according to the Whipple-Le Claire equation. Activation energies for grain-boundary diffusion of Pr(3+) in LaCoO(3) and LaFeO(3) materials were 264 +/- 41 kJ mol(-1) and 290 +/- 36 kJ mol(-1) respectively. Finally, a correlation between activation energies for cation diffusion in bulk and along grain boundaries in pure and substituted LaBO(3) materials (B = Cr, Fe, Co) is discussed.     

镧助剂对Fe/ZrO2催化剂结构及F-T反应性能的影响

用ＸＲＤ，Ｍｏｓｓｂａｕｅｒ谱，ＴＰＲ，ＣＯ－ＴＰＤ和ＣＯ加氢反应性能测试等手段研究了镧助剂对Ｆｅ／ＺｒＯ２催化剂结构及Ｆ－Ｔ合成催化剂性能的影响。结果表明，不同的制备方法明显影响催化剂的结构及反应的性能，镧助剂以Ｌａ２Ｏ３形式存在时，催化剂上甲烷选择降低，烯烃选择性提高；镧助剂以ＬａＦｅＯ３形式存在时，催化剂的催化活性大大提高，但同时甲烷选择性上升，烯烃选择性下降。     

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen carrier for partial oxidation of methane

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen cartier for partial oxidation of methane in the absence of gaseous oxygen was investigated by continuous flow reaction and sequential redox reaction. Methane was oxidized to syngas with high selectivity by oxygen species of perovskite oxides in the absence of gaseous oxygen. The sequential redox reaction revealed that the structural stability and continuous oxygen supply in redox re-action decreased over La0.8Sr0.2Fe0.9Co0.1O3 oxide, while LaFeO3 and Lao.sSro.2FeO3 exhibited excellent structural stability and continuous oxygen supply.     

纳米晶La_(1-x)Eu_xFeO_3的合成、表征及催化甲苯燃烧反应活性(英文)

Nanostructured LaFeO3 and substituted La1-xEuxFeO3 (x = 0.1, 0.15, and 0.2) perovskites were synthesized by sol-gel auto-combustion and their activities during the combustion of toluene were evaluated. The structure and physico-chemical properties of the perovskites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and BET surface area analyses. The compounds were crystallized as a perovskite phase with an orthorhombic structure. The mean particl...     

Effect of La on Partial Oxidation of Ethanol to Hydrogen over Ni／Fe Catalysts

The partial oxidation of ethanol to hydrogen was investigated over Ni/Fe/La catalysts prepared by the co-precipitantion method.the effects of introduction of La promoter and the reaction temperature on the catalytic performance were studied.It was found that the introduction of La into Ni/Fe catalysts is helpful to increase the selectivity to hydrogen and the stability of the catalysts.The results of XRD and XPS characteri-zation show that the structure of the catalyst was changed during the reaction.The existence of LaFeO3 species is possibly the main reason of the increase of the catalyst stability.     

氧化镁表面修饰稀土催化材料的制备和气敏性能

本文采用湿化学过程的柠檬酸络合法、可控化学沉淀法和溶胶-凝胶法合成了纳米复合金属氧化物LaFeO3,利用各种分析方法对材料的物性和结构进行了分析和表征;并测定了材料对氧化性气体和还原性气体的气敏性能．研究结果表明LaFeO3复合物对NO2在350℃灵敏度高达127．83,特别通过添加MgO对基材进行表面修饰灵敏度提高到845．37,约添加前的70倍．本文还进一步考察了添加质和添加量对基材的结构和气敏性能的影响,并通过研究材料表面对气体的吸脱附性能和元素电子结合能的变化对敏感作用机制进行了深入分析和探讨．     

Microstructural and surface characterization of solid state sensor based on LaFeO3-sigma oxide for detection of NO2

NO2 adsorption on non-stoichiometric perovskite-type LaFeO3-sigma thick films increases the density of charge carriers (holes), thus facilitating the detection of NO2 by conduction measurements. In this work, the microstructures and induced defects that control the sensing behaviour of LaFeO3-sigma were investigated in depth. LaFeO3-sigma powders were prepared both by thermal decomposition of a La[Fe(CN)6].nH2O complex at 700 degrees C and by using a sol-gel method at 500 degrees C. Scanning electron microscopy (SEM) revealed crystallites varying in size from 100 to 300 nm depending on the decomposition temperature. Surface analysis by X-ray photoelectron spectroscopy (XPS) confirmed that sintering in nitrogen is much more effective for reducing the amount of surface oxygen than is sintering in air. At low operating temperature, there is a drift of the output response associated with the ongoing process of bulk equilibration, but it is much less at 350 degrees C. It is obvious that a variation of [Oad]/[Olattice] with sintering conditions represents the relative gas adsorption capability.