Application of an Ion Beam Technique for the Design of Visible Light-Sensitive, Highly Efficient and Highly Selective Photocatalysts: Ion-Implantation and Ionized Cluster Beam Methods

As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO₂ and Ti-containing zeolites with highly accelerated metal ions (V⁺, Cr⁺, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO₂ thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO₂ thin films that are able to operate not only under UV light but also under visible light irradiation.     

FeZSM－5沸石上乙苯的吸附态及氧化脱氢

ＦｅＺＳＭ－５吸附乙苯前后的ＩＲ、ＸＰＳ、ＥＳＲ及Ｍｏｓｓｂａｕｅｒ谱表明，乙苯分子的侧链和苯环与ＦｅＺＳＭ－５的活性位（以Ｆｅ为中心的结构单元）同时发生配位络合作用，减弱了乙苯分子侧链的α和β位Ｃ－Ｈ键，使其活化，在氧存在下易发生氧化脱氢反应生成苯乙烯．Ｆｅ（Ⅲ）是乙苯氧化脱氢的活性中心，尤其是骨架不饱和配位的Ｆｅ（Ⅲ）对活化乙苯分子起到了关键作用，碱金属平衡阳离子起到了助催化剂的作用．骨架Ｆｅ（Ⅲ）比非骨架Ｆｅ（Ⅲ）具有更高的氧化脱氢活性     

The Reactivity of Cr‐Te Superlattice Reactants and of Co‐deposited Cr‐Te Films: Studies with in‐situ X‐ray Diffractometry

The reactivity of a Cr‐Te multilayer film consisting of 326 Cr/Te double‐layers with about 88(3) at% Te was investigated with in‐situ X‐ray diffraction. The occurrence of a superstructure reflection caused by the multilayer system is observed. During the annealing procedure between 80 and 90 °C the layer‐by‐layer arrangement is destroyed and elemental Te crystallizes. After 6 h isothermal annealing at 140 °C CrTe₃ starts to crystallize. The amount and the crystal size of CrTe₃ increase with raising temperature and Te is consumed during the growth process. At 220 °C the formation of crystalline Cr₂Te₃ is observed and between 220 and 260 °C CrTe₃ is completely decomposed into Cr₂Te₃. The two Cr tellurides grow as highly textured materials. The size of CrTe₃ crystals is significantly larger than that of Cr₂Te₃. For a co‐deposited Cr‐Te film with composition 77(3) at% Te the tri‐telluride and elemental Te crystallize simultaneously. The texture of CrTe₃ is less pronounced and different reflections of the tri‐telluride occur besides the (h00)‐reflections. Up to 160 °C a pronounced increase of the crystallite size is observed and the crystals are significantly larger than those obtained with the multifilm sample. At 130 °C the crystallization kinetics seem to be controlled by nucleation.     

High-temperature transformations of Cu-rich hydrotalcites

CuM(II)Al ternary hydrotalcites (M(II) = Ni, Co and Mg) with a (Cu+M(II))/Al atomic ratio of 3.0 and Cu/M(II) atomic ratio of 5.0 were synthesized by coprecipitation under low supersaturation. Powder X-ray diffraction of the as-synthesized samples showed a pattern characteristic of hydrotalcite-like (HT-like) structure (JCPDS: 41-1428). Thermal analyses of these samples showed four stages of weight loss/heat change when recorded in nitrogen. Analysis of the evolved gases characterized the nature of these transformations. The thermoanalytical effects differed significantly especially for the high-temperature transformations, when the treatment was performed in oxygen. In situ powder X-ray diffraction of the samples was carried out to elucidate the phase evolution of these compounds. Surprisingly formation of CuO was noted at temperatures around 200°C well below the destruction of the layered network. The nature of the resulting phases varied with both the nature of the co-bivalent metal ion and the heating atmosphere. FT-IR spectroscopy confirmed the retention of carbonate ions at higher temperatures (above 700°C), although the concentration of carbonate anion (most likely unidentate) varied with the calcination temperature. The crystallinity of CuO increased significantly above 600°C, probably through dissociation of copper oxycarbonate. Significant differences in the thermal transformation temperatures (for the third and the fourth transformations) of these samples containing different co-bivalent metal ions were not observed. This suggests that an association of the co-bivalent metal ions and/or trivalent metal ion in this phase is unlikely. A plausible thermal evolution scheme of these hydrotalcites is proposed.     

Ag／Al2O3选择性催化丙烯还原氮氧化物表面反应机理的原位红外光谱研究

 在富氧条件下Ag／Al2O3对以丙烯为还原剂选择性催化还原NOx的反应有很高的催化活性．本实验成功地利用原位红外光谱分析手段,在真实的催化反应条件下,探讨了丙烯选择性还原NOx的反应机理,证实了催化剂表面反应中间体Al－NCO和Ag－NCO虽在真空中稳定,但在实际反应条件下极为活泼．催化剂表面上R－ONO和R－NO2分解成NCO是整个反应的速度控制步骤．这一结论与在真空系统条件下对其反应机理的研究结果一致,证明了在这一反应体系中两种研究方法的相关性．同时本实验还从反应机理上探讨了催化剂的水蒸气中毒现象．水蒸气的存在阻碍了催化剂表面R－ONO和R－NO2的生成,并进一步阻碍了反应的速度控 制步骤,即R－ONO和R－NO2向Al－NCO和Ag－NCO的转化,但这是一种完全可逆的暂时中毒现象．结合相应的催化剂活性评价结果对表面反应机理进行了讨论．     

混合价化合物的研究(Ⅱ)─—电化学及现场光谱电化学方法研究非质子介质中Dawson结构杂多阴离子[HAs_2Mo_(18)O_(62)]~(n-)的电还原性质

以电化学和现场紫外－可见－近红外及现场FTIR光谱电化学方法对Dawson结构杂多阴离子［HAS2Mo18O62］5－在非质子介质（CH3CN）中的电还原过程进行了研究．结果表明，该杂多阴离子在非质子介质中经历4步单电子还原反应，所产生的杂多蓝阴离子在近红外区出现宽广的价间电荷转移吸收带，而红外区Mo＝O端键及Mo—O—Mo桥键的特征吸收峰在还原后均有不同程度的红移．     

On-probe pyrolysis desorption electrospray ionization (DESI) mass spectrometry for the analysis of non-volatile pyrolysis products

An on-probe pyrolyzer has been constructed and interfaced with desorption electrospray ionization (DESI) mass spectrometry (MS) for the rapid analysis of non-volatile pyrolysis products. The detection and analysis of non-volatile pyrolysis products of peptides, proteins and the synthetic polymer poly(ethylene glycol) were demonstrated with this instrument. The on-probe pyrolyzer can be operated off-line or on-line with the DESI source and was interfaced with a tandem MS (MS/MS) instrument, which allowed for structure characterization of the non-volatile pyrolytic products. Advantages of this system are its simplicity and speed of analysis since the pyrolysis is performed in situ on the DESI source probe and hence, it avoids extraction steps and/or the use of matrices (e.g., as in MALDI–MS analyses).     

Cathodic deposition of ternary In+As+Sb alloys and formation of InAsxSb1−x

In+As+Sb alloys have been deposited onto Ni and Ti cathodes from tartaric acid solutions at pH 2. Homogeneous deposits of composition suitable for achieving InAs_xSb_1−x can be obtained from this medium. The As-to-Sb ratio can be controlled by properly selecting solution composition and deposition potential.X-ray photoelectron spectroscopy and X-ray diffraction analyses show that formation of III–V compounds occurs at room temperature. In reacts preferentially with As rather than with Sb, but crystalline phases formed at room temperature are Sb-rich. After annealing the In+As+Sb alloys at 250°C, the composition calculated from cell parameters appears similar to that measured by energy-dispersive X-ray analysis, suggesting that the entire deposit has been converted into the InAs_xSb_1−x crystalline phase.     

Investigation of surface structure and composition of in situ annealed Fe–Mn binary alloy samples using RHEED and electron spectroscopy

The formation of oxides at the surface of Fe–1.5%Mn and Fe–0.6%Mn binary alloys was investigated as a function of the conditions of the heat treatments. Both the influence of temperature and the atmosphere under which the experiments were performed were studied. The range of annealing temperatures was adjusted to 800°C. The atmosphere consisted of a mixture of N₂–5%H₂ and traces of water vapour, with different fixed dew points ranging from −10°C to −30°C. The state of the annealed surfaces was determined using in situ analytical devices attached to the annealing reactor in order to avoid surface contamination or the formation of native oxides after the experiments due to contact with air. The structure and composition of the surfaces were determined by reflection high-energy electron diffraction (RHEED) and electron spectroscopy (XPS, AES). Copyright © 2002 John Wiley & Sons, Ltd.     

Electrochemical studies of the oxidation mechanism of polyamide on glassy carbon electrode

Polyamides containing N-methyl pyrroles and N-methyl imidazoles are a type of small molecule that can bind and recognize the bases of DNA with high affinity and specificity. Five polyamides were studied at glassy carbon electrode in acetate buffer by cyclic and differential pulse voltammetry to clarify their redox pathways. The polyamide electrochemical responses are compared by peak currents and peak potentials. The slopes of the three anodic E_p vs. pH plots of a typical polyamide are linear and show 0.059, 0.057, 0.056 V per pH in acid media, respectively, which correspond to a mechanism involving the equal number of electrons and protons. A possible mechanism for the redox pathway of various polyamides is proposed: the oxidation product of imidazole ring is acylamide and the results of in situ UV–Vis spectroscopy at Pt web electrode support the proposed mechanism. electrospray ionization mass spectroscopy (ESI-MS) indicates that one or two oxygen atoms are added into polyamide molecule after electrochemical oxidation.