超声雾化反应法制备CeO2纳米粉体

以硝酸铈和碳酸氢铵为原料,采用超声雾化反应法制备了纳米CeO2粉. 用红外光谱(IR)、 X射线衍射分析(XRD)和透射电子显微镜(TEM)技术,对制得的纳米CeO2纳米粒子的物相结构、形貌特征、成分等进行了表征. 结果表明,双液超声雾化法能制备出颗粒分散性好,粒度分布均匀的纳米CeO2粒子,所得CeO2粒子为萤石型结构,粒径约为3～5 nm左右. 初步探讨了用超声雾化反应法制备纳米粉的机制,认为CeO2纳米粒子的成核和长大受到液滴大小的限制,是一个液相的微区反应过程,正是液滴的微小体积保证了更小纳米粒子的形成.     

爆轰法制备球形纳米CeO2粉末

采用爆轰合成的方法,以Ce(NO3)3·6H2O为原料,制得了CeO2纳米粒子. 炸药采用黑索金粉,添加剂为CO(NH2)2,NaNO2. 爆轰产物经水洗,烘干后,利用X射线衍射仪器和高分辨率透射电镜对实验结果进行了分析. XRD结果表明,该法所得到的CeO2为立方晶系,颗粒平均粒度为33 nm. TEM图像显示其颗粒呈球形,颗粒大小主要分布在20～40 nm之间,颗粒具有较好的分散性. 球形纳米CeO2颗粒的形成原因有两点:(1) 由于爆轰过程的快速性和急剧冷却的特点,CeO2晶粒来不及择优生长; (2) 产物Na2CO3的熔点较低,爆轰时呈熔融状态包覆在CeO2晶核的周围,阻隔了CeO2晶粒的团聚生长.     

CeO2形态对CeO2/Au电极催化氧化乙醇的影响

利用煅烧和微波诱导燃烧法合成了不同形态的CeO2.利用TG-DSC对前驱物Ce2(CO3)3进行了热分析,结果表明产物为CeO2.分别用XRD,Raman光谱仪,YE-SEM,FT-IR等对产物结构进行了表征.XRD和Raman分析结果证明,产物具有与萤石相似的结构.FT-IR分析表明:在约1382 cm-1处为Ce-O键的伸缩震动.FE-SEM照片说明用煅烧法合成的产物比用微波诱导燃烧法合成的产物孔隙率更低.分别用纯金电极、不同形态CeO2修饰的玻碳电极和金电极在1.0 mol·L-KOH和1.0 mol·L-1乙醇的混合液中对乙醇进行电催化氧化实验,结果表明:通过CeO2对金电极的修饰可以提高其催化活性,CeO2的形态会影响电流强度.     

同轴静电纺丝技术制备CeO2纳米管及光催化性能研究

采用同轴静电纺丝技术,以硝酸铈、聚乙烯吡咯烷酮、N,N-二甲基甲酰胺和氯仿为原料,制备了CeO2纳米管。用差热-热重分析、X射线衍射、扫描电镜、透射电镜和能谱仪对样品进行了表征。考察了CeO2纳米管对罗丹明B溶液的光催化性能。结果表明:所得到的产物属于立方晶系、空间群为O5H-FM3M的CeO2纳米管,CeO2纳米管平均外径约270 nm,内径约110 nm,管壁厚度约80 nm,长度>20μm,对其形成机理进行了分析。相对于CeO2纳米线、纳米带和CeO2颗粒,CeO2纳米管对罗丹明B的降解率有明显提高。     

单晶菱形CeOHCO3片状物的制备及其向CeO2的热转换

以硝酸铈铵和尿素为反应物,γ-氨丙基三乙氧基硅烷(KH550)为助剂,通过沉淀反应制得了单晶菱形CeOHCO3片状物。然后将CeOHCO3在600℃空气气氛中灼烧获得了菱形CeO2。通过XRD和SEM对反应物中是否含有KH550助剂所得的产物进行了分析,结果发现只有含有KH550才能获得菱形CeOHCO3片状物,并且在灼烧过程中产物的形貌仍保持菱形。然后采用TEM对菱形CeOHCO3和CeO2进行了表征,结果发现CeOHCO3为单晶产物而灼烧后所得的CeO2为多晶产物。     

Au4团簇上甲酸分解反应机理的理论研究

采用密度泛函理论方法对Au4团簇上甲酸分解反应的反应机理进行了研究,并考察了Au4团簇的两个催化活性位点。在路径Ⅰ和路径Ⅱ中,HCOOH分解的产物是CO2和H2。在路径Ⅲ和路径Ⅳ中,HCOOH分解的最终产物为CO和H2O。此外,本文研究了CO2、H2和CO、H2O两种产物的相互转化,即路径Ⅴ和路径Ⅵ。研究结果表明,路径Ⅰ和路径Ⅱ的活化自由能垒较低,即在Au4团簇上HCOOH更易分解得到CO2和H2,此外两种产物之间不容易转化。进一步研究发现团簇的大小及CeO2载体对HCOOH分解脱氢路径的活化自由能垒有一定的影响。     

从四元混合稀土氯化物LaCl3-CeCl3-PrCl3-NdCl3中分离Ce02的研究

本文以湿空气为氧化剂,主要研究稀土氯化物LaCl3-CeCl3-PrCl3-NdCl3的氧化反应特性,根据铈和非铈稀土元素氯化物的氧化产物不同实现CeO2的分离.最佳氧化反应温度和时间分别为600~℃和60min,实验产物经x射线衍射分析,只有CeO2的衍射峰,实现了单一稀土CeO2的分离.     

蛋清蛋白辅助水热法制备CeO_2纳米棒及其发光性能

本文以氯化铈和氢氧化钠为反应原料,以新鲜蛋清为络合剂,探索在水热体系中制备CeO2纳米棒。通过XRD、FESEM等测试手段对其进行了结构和形貌分析;应用荧光光谱法对样品的发光性能进行了测试。XRD结果表明,实验所得产物为立方萤石结构CeO2。FESEM分析可知,所得CeO2纳米棒为规则六方柱结构,其长度约为200 nm、直径约为几十纳米。荧光光谱分析可知其在紫蓝色发光区具有较强的发光性能。     

CeO_2修饰炭载体负载PdPt二元合金催化剂及其在甲酸氧化电催化中的应用

用CeO2修饰炭粉做载体,使用有机溶胶法还原PdPt二元合金的方法制备了一系列PdPt/CeO2-C催化剂.借助电化学测试,探讨催化剂中不同Pd与Pt原子比例的PdPt二元合金和不同含量的CeO2对于甲酸电氧化催化活性的影响.不断减少PdPt合金中Pt的比例可以促使甲酸氧化的起始电位前移,当Pd：Pt=15：1时氧化电流出现极值;同时,随着催化剂中CeO2含量的增加,催化剂对于HCOOH氧化的电流密度增加,当含量为15%时达到最大值.相对于Pd/C催化剂,在Pd15Pt1/15CeO2-C催化剂表面的甲酸氧化反应起始电位负移至少0.1V,氧化的电流密度提高60%以上.结合X射线衍射（XRD）,X射线光电子能谱（XPS）,透射电镜（TEM）和热重（TG）等测试数据可以发现,当极少量的Pt与Pd形成合金,Pt与Pd之间产生电子效应,使得合金表面HCOOH氧化的过电位降低;而CeO2的添加不仅有助于PdPt二元合金的分散,更有可能改变甲酸在PdPt表面的氧化反应路径,发挥双功能机理.     

不同制备方法对氧化铈结构及甲苯催化燃烧性能的影响

采用溶胶-凝胶-超临界干燥法、水热法及共沉淀法分别合成了氧化铈气凝胶(CeO2-A)、纳米棒(CeO2-R)和纳米片(CeO2-F).考察了不同形貌氧化铈的催化燃烧甲苯性能,通过多种方法分析表征了氧化铈样品的微观结构,讨论了不同方法制得的CeO2形貌结构对催化性能的影响.结果表明,CeO2-R和CeO2-F比表面积较低...     

离子聚合物微球负载钯催化甲酸分解产氢

催化甲酸分解产氢是氢气储存和氢能利用的重要途径。以对乙烯基吡啶和1,3,5-三(溴甲基)-2,4,6-三甲基苯为原料,通过季胺化和聚合,制备了树枝状离子聚合物微球。负载Pd纳米粒子后用于催化甲酸分解产氢。微球的离子交换性能、含N特性以及分子内部空穴使制备的Pd 纳米粒子具有高分散性、小尺寸、均一粒径和优化的电子结构。考察了甲酸浓度和反应温度对产氢速率的影响。结果表明,在50℃、甲酸浓度为1 M、甲酸与钯摩尔比为200、甲酸与甲酸钠摩尔比为3的优化反应条件下,甲酸完全分解时间为30 min。催化剂使用4次后活性无明显下降。     

Improved perovskite solar cell efficiency by tuning the colloidal size and free ion concentration in precursor solution using formic acid additive

Improving the quality of the perovskite active layer is crucial to obtaining high performance perovskite solar cells(PSCs). In this work, by introducing formic acid into the formamidinium lead iodide(FAPbI3)precursor solution, we managed to achieve reduced colloidal size in the solution, leading to more uniform deposition of FAPbI3 film with lower trap state density and higher carrier mobility. The solar cells based on the FAPbI3 absorber layer modified with formic acid show significantly better photovoltaic performance than that on the reference FAPbI3 film without formic acid. The device performance shows a close correlation with the colloidal size. Within the range studied from 6.7 to 1.0 nm, the smaller the colloidal size is, the higher the solar cell efficiency. More specifically, the cell efficiency is improved from17.82% for the control cell without formic acid to 19.81% when 0.764 M formic acid was used. Formic acid has also been added into a CH_3NH_3PbI_3(MAPbI_3) precursor solution, which exhibits a similar effect on the resulting MAPb I3 films and solar cells, with efficiency improved from 16.07% to 17.00%.     

Electrochemical deposition of Pd nanoparticles on indium-tin oxide electrodes and their catalytic properties for formic acid oxidation

Pd nanoparticles (NPs) were directly deposited on indium-tin oxide (ITO) electrodes by cyclic voltammetry (CV) in a bulk Pd²⁺ solution and the size of the Pd (NPs) was evaluated by SEM. The electrochemical deposition conditions of the Pd NPs were varied according to a scan rate. As the scan rate was decreased, the size of the Pd NPs increased, but the formic acid catalytic property was weakened. With regard to cycle number, with increased cycling, the size of the Pd NPs increased but the formic acid catalytic property decreased. As the conditions of electrochemical deposition were varied, the particle size and catalytic activity for formic acid were also changed.     

聚苯胺-改性木质素磺酸钠复合材料基活性炭负载Pd催化剂对甲酸氧化的催化性能

将聚苯胺/改性木质素磺酸钠复合材料在不同炭化温度下进行处理得到活性炭材料，利用红外光谱、拉曼光谱、比表面积分析和扫描电镜等手段对其结构和表面性质进行了表征。通过液相还原方法将Pd纳米颗粒负载在所制备的活性炭材料上，获得Pd/C催化剂用于甲酸氧化，并采用X射线衍射、透射电镜和电化学测试等方法对该Pd/C催化剂进行表征。结果表明，以800℃下炭化得到的活性炭材料为载体所制备的Pd-AC800催化剂其催化性能最优；Pd粒径为5.4 nm，电化学活性面积为53.78 m²/g。由于在该催化剂上甲酸氧化通过直接途径进行，Pd-AC800可用作直接甲酸燃料电池的催化剂。     

Decreasing the shell ratio of core-shell type nanoparticles with a ceria core and polymer shell by acid treatment

Core-shell type nanoparticles with a ceria core and polymer shell have good dispersibility. Some applications, such as fillers for increasing the refractive index and/or protecting resin films from ultraviolet (UV) light, i.e., UV cutting, require a smaller shell. Previous studies have decreased the shell weight by heat treatment in gas; however, the dispersibility of the treated nanoparticles was poor in water or alcohol. In this study, we investigated the efficacy of acid treatment for decreasing the shell weight and also evaluated the dispersibility of acid-treated nanoparticles. The thus-formed nanoparticles treated by acetic acid and formic acid show not only good dispersibility but also a well decreased shell thickness. The structure of the shell after acetic acid treatment was found to be the same as that of the untreated core-shell nanoparticles; moreover, acetic acid was present in the shell. Furthermore, by using the acetic-acid-treated nanoparticles, a transparent resin film without nanoparticle aggregation could be obtained.     

Quantitation of formate by solid-phase microextraction and gas chromatography--mass spectrometry utilizing a [13C]formate internal standard

A new method for the analysis of formic acid was developed using gas chromatography-electron impact ionization mass spectrometry in the selected ion monitoring mode and solid-phase microextraction. Using this method with [13C]formic acid as an internal standard, the peak area ratio of [12C]formic acid/[13C]formic acid was not affected by differing methanol or sulfuric acid concentrations during the esterification and fiber adsorbing step. In comparison, the peak area ratio of formic acid/acetonitrile as detected by conventional GC with flame ionization detection was greatly affected by methanol or sulfuric acid concentrations. The formic acid calibration curve of our method showed excellent linearity over the range 5 to 200 microM. The within- and between-run assay relative standard deviations for the formic acid concentration were all less than 1.70%.     

规则中孔氧化铈的纳米铸型合成及作为高CO氧化活性金催化载体的应用

以有序的中孔炭材料CMK-3为模板,以硝酸铈为前体,利用纳米铸型法合成了具有规则结构的中孔氧化铈,考察了模板脱除温度对中孔氧化铈微结构的影响.热重、元素分析、X射线衍射、透射电镜和氮气物理吸附结果表明,炭模板的脱除温度可低至350℃,所得氧化铈具有二维六方规则结构,比表面积高达167 m~2/g,孔径分布集中在3～5nm.采用胶体沉积法将2-5nm的金溶胶粒子沉积到所得氧化铈表面制得了Au/CeO_2催化剂,考察了Au/CeO_2在CO氧化反应中的活性.结果表明,该催化剂的活性较常规氧化铈制备的金催化利有明显提高,这可能与载体的规则结构有关.     

On the origin of reactive Pd catalysts for an electrooxidation of formic acid

We investigated the origin of the reactive surface of Pd catalysts during the electrocatalytic oxidation of formic acid. XPS analysis was the primary tool adapted to characterize the surface changes in Pd catalysts arising from interactions with formic acid. Pd catalysts showed fast deactivation, though their activity could be simply recovered by applying a reduction potential at which hydrogen evolution reaction can occur. XPS analysis revealed that the surface of Pd catalysts is significantly affected by interaction with formic acid, thus confirming that the surface coverage of oxygen species plays an important role in formic acid electrooxidation on the Pd catalysts. At the same time, mass transfer of formic acid also has an effect on the deactivation of Pd catalysts.     

炭载Pd-Pb合金纳米粒子对甲酸电催化氧化的影响

通过浸渍还原方法制备了具有不同化学计量比的炭载Pd-Pb合金纳米粒子催化剂. XRD和TEM测试结果表明, Pd-Pb合金纳米粒子的晶格常数随Pb元素含量的增加而增加, 相应的粒子尺寸随Pb元素含量的增加而减小. 循环伏安、CO溶出和计时电流等电化学测试结果表明, 炭载Pd-Pb合金纳米粒子催化剂对甲酸氧化的电催化活性随Pb含量的增加而降低.     

水热氧化法制备γ-Mn2O3

研究了用电化学方法制备的铂微粒修饰的聚２,５二甲氧基苯胺电极对甲酸的电催化氧化,用ＳＥＭ、ＸＰＳ表征了这种电极材料的表面结构,结果表明,这种复合电极对甲酸在酸性介质中电化学氧化具有很高的催化活性,较之裸铂电极其催化电流提高１００多倍．循环伏安法制备的铂微粒较均匀地分布在聚合物上,其粒径大约为３００ｎｍ．研究了铂微粒载量、阴离子种类、反应温度和浓度等因素对电极催化活性的影响．