Pt/Ba-Al-O催化剂储存NOx的性能和机理研究

采用共沉淀法制备了Pt/Ba-Al-O样品,用XRD,NO－TPD以及NOx储存量测量等手段对样品进行了表征,并对NOx的储存机理进行了探讨。结果表明,样品中的主要成分是BaAl2O4,有少量BaCO3存在。在催化剂表面的Pt有两种吸附位,吸附位1为NO提供了吸附位,对应低温区的NO脱附峰;吸附位2例NO和O2在催化剂表面反应生成硝酸盐和亚硝酸盐,对应高温区的NO脱附峰,当吸附温度为300度,O2的体系分数为1．3％时,NO的脱附量达到了最大值。经过还原处理样品的NO中附能力比经过氧化预处理的样品强得多,样品储存NOx的最佳温区为300－450度。     

BaCeO3 钙钛矿型氧化物的储氮和抗硫性能研究

采用改进的溶胶 凝胶法制备了钙钛矿结构的BaCeO3 样品 ,在此基础上再用浸渍法制备了Pt/BaCeO3 、Rh/BaCeO3 、Pt Rh/BaCeO3 样品 ,并用机械混合γ Al2 O3 ,再浸渍贵金属的方法制备了Pt/BaCeO3 /γ Al2 O3 、Rh/BaCeO3 /γ Al2 O3 、Pt Rh/BaCeO3 /γ Al2 O3 样品 .储氮量 (NSC)结果表明 :对未加γ Al2 O3 的BaCeO3 来说 ,贵金属的加入反而使NSC减小 .加入贵金属催化剂的储氮量 (NSC)大小为 :Pt的最大 ,Rh的次之 ,Pt Rh的最小 .γ Al2 O3 的加入对BaCeO3 吸收NO和O2 没有影响 .而对于BaCeO3 /γ Al2 O3 样品 ,贵金属的加入使NSC值提高了 3倍以上 .讨论了贵金属加入到BaCeO3 /γ Al2 O3 样品中显著提高样品储氮能力的原因 .结合XRD结果表明 ,钙钛矿BaCeO3 相是Ba -Ce -O样品主要的NOx 储存活性中心 .NSC结果还表明 ,BaCeO3 和Pt/BaCeO3 催化剂在SO2 为≤ 0 .0 0 6 %时具有较好的抗硫性能 .而Pt/BaCeO3 /γ Al2 O3 催化剂不但具有较好的储氮能力而且具有更好的抗硫性能 .     

失活催化剂中金属杂质测定方法研究

针对失活催化剂中残余的积炭、硫对金属杂质含量测定的影响,建立了一种以硝酸-高氯酸体系氧化溶解样品,ICP-AES准确测定失活加氢催化剂中沉积在催化剂表面的金属杂质Fe、Na、Ca、Mg含量的方法.测定结果表明,该方法的精密度小于5%,回收率在95%-113%之间,与其他方法相比,本方法准确、可靠,可用于实际分析.     

X射线荧光能谱法测定贵金属含量的测量不确定度分析

研究了 X射线荧光能谱法测定贵金属含量的不确定度来源 ,通过 A类评定和 B类评定方法建立了测量结果不确定度的评定程序 ,使测量结果更具有科学性 ,从而能够规范地、定量地进行产品合格判定     

细菌视紫红质近场光存储特性的研究

结合近场光学显微镜，利用菌紫质M态和基态之间的跃迁，对BR—D96N样品作了静态近场光存储特性的研究。结果表明，近场区域内细菌视紫外质在光激发前后对红光的吸收有较大差别，而且激发后无光照时会缓慢弛豫到激发前的状态，具有光致变色特性和热弛豫特性，可望作为近场光存储材料和微光学信息处理器件材料。     

Proton conductivity and low temperature structure of In-doped BaZrO3

The proton conductivity and structural features of In³⁺ substituted BaZrO₃ samples, i.e., BaZr_1−xIn_xO_3−δ, were investigated. Rietveld analysis of low temperature (10 K) neutron powder diffraction data collected on as-prepared and deuterated samples confirmed cubic symmetry (space group Pm-3m) for all compositions. The level of oxygen vacancies refined in the as-prepared samples were in good agreement with the values expected to conserve charge neutrality, whilst an increase in oxygen occupancy, reflecting the incorporation of OD⁻ species, was obtained for the deuterated materials. An expansion of the unit cell parameter, a, was observed as a function of In³⁺ doping as well as after the deuteration reaction. The conductivity of pre-hydrated and dry samples was measured using impedance methods. For 25% In-doped BaZrO₃, the low T (300 °C) conductivity of the heating cycle of the dried sample was greater than that of the cooling cycle of the pre-hydrated sample indicating a greater number of protons in the nominally dry sample. In contrast, the conductivity values were similar at higher temperatures e.g. T > 500 °C where proton conduction is not dominant.     

Engineering of SERS Substrates Based on Noble Metal Nanomaterials for Chemical and Biomedical Applications

Abstract

Surface-enhanced Raman scattering (SERS) has attracted great interest due to its remarkable enhancement, excellent sensitivity, and the “fingerprinting” ability to produce distinct spectra for detecting various molecules. Noble metal nanomaterials have usually been employed as SERS-active substrates because of their strong SERS enhancement originated from their unique surface plasmon resonance (SPR) properties. Because the SPR property depends on metal material's size, shape, morphology, arrangement, and dielectric environment around metal nanostructures, the key to wider applications of SERS technique is to develop plasmon-resonant structures with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. This review presents a general view on the theory background of SERS effect and several basic concepts and focuses on recent progress in engineering metallic nanostructures with various morphologies using versatile methods for improving SERS properties. Their potential applications in the field of chemical detection and biological sensing are overviewed.     

BaZrO3和CaZrO3能带和光学性质的第一性原理研究

采用基于密度泛函理论基础上的CASTEP软件包,计算了BaZrO3和CaZrO3的能带以及光学性质.计算得到BaZrO3直接带隙和间接带隙分别为3.49 eV和3.23eV,CaZrO3直接带隙和间接带隙分别为3.73 eV和3.38 eV.对这两种材料的介电函数、吸收系数、反射系数、折射系数、湮灭系数和能量损失系数等光学系数进行了计算,并基于电子能带对光学性质进行了解释.得出,光学特性的异同是由于其内部微观结构上的异同所引起的.     

A computational insight of electronic and optical properties of Cd-doped BaZrO3

First principles calculations are carried out to explore the structural, electronic and optical properties of Pure and Cd-doped BaZrO₃, an oxide-based perovskite material. To investigate these properties, Ultra-soft pseudo-potential (USP) is used as incorporated in Cambridge Serial Total Energy Package (CASTEP). In this system, the generalized gradient approximation (GGA) proposed by Perdew-Burke Erzenhoff (PBE) is used for exchange correlation potential. Cadmium (Cd) doping at Ba-site is more favorable as compare to Zr-site because new gamma points occurred which not only affects the electronic structure of the BaZrO₃ but also reduces the band gap from 3.127eV to 1.326eV and a transformation from indirect to direct band gap occurred. After doping, Fermi level shifted towards valance band which exhibits the characteristic of p-type semiconductor material. In optical properties, the absorption spectrum, refractive index (2.73), dielectric constants, reflectivity and energy loss function of the doped in comparison with pure material is presented. It has good optical response in UV region. The doping changes the optical behavior of BZO drastically thus making this material more effective for optoelectronic applications.     

金属纳米颗粒LSPR光纤生物传感DDA方法研究

研究了金属纳米颗粒的局部表面等离子体共振(LSPR)行为,并讨论了其在光纤生物传感领域的应用.采用离散偶极近似(DDA)的方法,从理论上分析了金属纳米颗粒的尺寸、形状对其传感灵敏度的影响.计算结果显示,金属纳米颗粒的等离子共振吸收峰同时受到颗粒尺寸和形状的影响,但形状对其传感灵敏度的影响最为明显,计算结果与实验数据能较好地吻合.