碱性介质中L-赖氨酸在纳米金膜电极上的吸附和氧化过程

采用原位红外反射光谱(in situ FTIRS)和循环伏安法(CV)研究了碱性介质中L-赖氨酸在纳米金膜电极(nm-Au/GC)上的解离吸附和氧化过程. 研究结果表明, 在碱性溶液中以阴离子形式存在的赖氨酸[-OOC—CH—NH2—(CH2)4—NH2]在低电位区间(-0.95~-0.80 V, vs. SCE)发生部分解离, 生成AuCN-物种(约2110 cm-1), 同时赖氨酸阴离子的羧基侧还可通过两个氧原子与金电极表面相互作用. 随着电位的升高, 吸附态CN-氧化产生NCO-, OCN-和AuCN, 其对应的红外吸收峰分别位于2254, 2168和2226 cm-1附近.     

酸性溶液中过渡金属及合金纳米薄膜电极的异常红外效应研究

以循环伏安方法在玻碳载体上制备纳米级厚度的过渡金属 (Pt,Pd ,Rh ,Ru)和合金 (PtPd ,PtRu)薄膜电极 ,并运用原位FTIR反射光谱研究了CO的吸附过程 .发现所制备的纳米薄膜电极均具有异常红外效应 ,即与本体金属电极相比较 ,吸附在纳米薄膜电极上的CO分子的红外吸收被显著增强 ,并且红外谱峰方向倒反 .本文的结果进一步证明异常红外效应是一种新的、普遍的现象 ,主要取决于过渡金属或合金膜的结构和厚度 .对异常红外效应的深入认识 ,不仅将推动红外反射光谱及界面电化学理论的发展 ,而且将在表面和界面分析中得到广泛应用 .     

中性介质中L-丝氨酸在Pt电极上解离吸附和氧化的原位FTIR研究

运用电化学循环伏安(CV)和原位红外反射光谱(in situ FTIRS)研究了中性介质中L-丝氨酸在Pt电极上的解离吸附和氧化过程. 结果表明, 在中性溶液中, 以两性离子形式存在的丝氨酸可以在很低的电位下(-0.6 V, vs. SCE)在Pt电极表面发生解离吸附, 生成强吸物种一氧化碳(COL)、(COB)和氰负离子(CN-). 研究结果还表明, 当电位低于0.7 V(vs. SCE)时, CN-能稳定存在于电极表面, 抑制丝氨酸的进一步反应. 在更高电位时则主要为丝氨酸分子的氧化过程.     

铂电极上苯和苯磺酸吸附定向的现场红外反射吸收光谱电化学方法研究

本文用现场红外反射吸收光谱电化学方法和循环伏安法研究铂电极上苯和苯磺酸的吸附定向.对于苯/铂势系,电势在-0.6至0.0 V(相对饱和甘汞电极)内,苯主要以垂直方式吸附;在0.0至0.8 V内则主要以平躺方式吸附.对于苯磺酸/铂体系,电势在-0.4至0.0 V内,苯磺酸分子中的苯环主要呈垂直吸附且SO_3H基团远离电极表面;在0.0至1.0 V内则主要以倾斜平躺方式吸附,SO_3H基团通过其中的两个氧原子吸附于电极表面上.     

核-壳结构Au-Pt纳米粒子的光谱表征和电催化性能

用化学还原法合成了核-壳结构Au-Pt纳米粒子.紫外可见光谱(UV-Vis)、电化学循环伏安(CV)和透射电子显微镜(TEM)表征结果指出，所合成的核-壳结构Au-Pt纳米粒子为球形，平均直径为27 nm.以CO为分子探针，结合透射红外光谱研究，发现CO以孪生吸附态形式(COT)吸附在Au-Pt纳米粒子上，在2110 cm－1和2063 cm－1附近分别给出对称和反对称红外吸收峰. CV研究结果指出Au-Pt/GC电极对CO的氧化有较高的催化活性，起始氧化电位较本体Pt电极提前了0.45 V，峰电位提前了0.11 V.     

碳载Pt/Sb_(ad)电极上乙醇电催化氧化特征和原位FTIR反射光谱研究

用电化学循环伏安法和原位 FTIR反射光谱法研究了 Sb在碳载纳米 Pt膜电极 (nm -Pt/ GC)表面不可逆吸附的电化学特性及酸性介质中乙醇的吸附和电催化氧化特性 .结果指出 ,当扫描电位的上限 Eu≤0 .5 0 V(SCE)时 ,Sbad可以稳定地吸附在 nm-Pt/ GC电极表面 .与未修饰的 nm-Pt/ GC电极上结果相比 ,Sbad修饰的 nm-Pt/ GC/ Sbad/ (nm-Pt/ GC)的催化活性显著增加 .测得当覆盖度θsb=0 .1 3 7时 ,修饰电极对乙醇的电催化活性最高 ,乙醇氧化的峰电位负移了 0 .1 5 V,峰电流增大了 1倍 .原位 FTIR反射光谱的结果从分子水平揭示了 Sb修饰对乙醇氧化反应途径的选择功能 .     

碱性介质中甘氨酸在纳米金膜电极上的吸附和氧化

运用原位红外反射光谱（in situ FTIRS）和电化学石英晶体微天平（EQCM）在分子水平上研究了碱性介质中甘氨酸在纳米金膜电极上的解离吸附和氧化过程.结果表明,甘氨酸在很低的电位下（－0.8 V, vs SCE）就可发生解离吸附.其解离产物氰基(CN－)与电极表面存在较强的化学吸附作用，形成AuCN－物种(红外吸收谱峰位于2100 cm－1附近).吸附在纳米金膜表面的CN－给出红外吸收显著增强、红外谱峰方向倒反和半峰宽增加的异常红外效应特征.吸附态CN－在低电位抑制H2O和OH－的吸附，当电位高于0.2 V可氧化产生OCN－；进一步升高电位到0.3 V则形成.溶液相物种OCN－和对应的红外吸收峰分别为2169 cm－1和2145 cm－1.实验结果指出，金以的形式溶解是导致电极表面质量显著减少的主要原因.     

铂电极上苯和苯磺酸吸附定向的现场红外反射吸收光谱电化学方法研究

本文用现场红外反射吸收光谱电化学方法和循环伏安法研究铂电析上苯和苯磺酸的吸附定向。对于苯/铂势系, 电势在-0.6至0.0V(相对饱和甘汞电极)内, 苯主要以垂直方式吸附; 在0.0至0.8V内则主要以平躺方式吸附。对于苯磺酸/铂体系,电势在-0.4V至0.0V内, 苯磺酸分子中的苯环主要呈垂直吸附且SO~3H基团远离电极表面; 在0.0至1.0V内则主要以倾斜平躺方式吸附, SO~3H基团通过其中的两个氧原子吸附于电极表面上。     

碱性介质中甘氨酸在Pt电极上解离吸附和氧化反应的原位红外反射光谱研究

运用原位红外反射光谱研究了碱性介质中甘氨酸在Pt电极上的解离吸附和氧化反应行为,并利用纳米Pt膜电极的异常红外效应鉴定反应过程中生成的表面吸附物种.结果表明:甘氨酸在Pt电极上极易发生解离,生成强吸附于电极表面上的氰基负离子,该吸附物种在低于0V电位下能稳定存在,并抑制甘氨酸的进一步反应.当电位高于0.2V时,氰基负离子被氧化为氰酸根离子进入溶液,使甘氨酸发生氧化反应,生成氰酸盐和碳酸盐等产物.     

电化学原位步进扫描时间分辨显微镜FTIR反射光谱

结合步进扫描傅立叶变换红外光谱仪和红外显微镜，建立了电化学原位步进扫描时间分辨显微镜FTIR反射光谱.采用微电极和利用纳米结构表面的异常红外效应，显著提高表面吸附物种的红外检测灵敏度和红外电极表面对极化电位的响应速度，使广泛应用的外反射型薄层红外电解池的时间常数(τ=R1Cd)从使用常规盘电极的约40 ms降低到0.65 ms.研究了酸性介质中CO在Pt电极上的吸附过程，谱图的时间分辨率达50 μs.     

In situ FTIR spectroscopic studies of CO adsorption on electrodes with nanometer-scale thin films of ruthenium in sulfuric acid solutions

A nanometer-scale thin film of ruthenium supported on glassy carbon (nm-Ru/GC) was prepared by electrochemical deposition under cyclic voltammetric conditions. Scanning tunneling microscopy (STM) was used to investigate the structure and to measure the thickness of the thin film. It has been found that the Ru thin film is composed of layered Ru crystallites that appear in a hexagonal form with dimensions of about 250 nm and thickness around 30 nm. In situ FTIR spectroscopic studies demonstrated that such a nanostructured Ru thin film exhibits abnormal infrared effects (AIREs) for CO adsorption (G.Q. Lu et al., Langmuir 16 (2000) 778). In comparison with CO adsorbed on a massive Pt electrode, the IR absorption of CO_ad on nm-Ru/GC was significantly enhanced. Moreover, the direction of CO_ad bands is inverted and the full width at half maximum of CO_ad bands is increased. It has been revealed that the enhancement factor of IR absorption of CO adsorbed on nm-Ru/GC electrodes depends strongly on the thickness of the Ru film. An asymmetrical volcano relationship between the enhancement factor and the thickness of the Ru film has been obtained. The maximum value of the enhancement factor was measured as 25.5 on a nm-Ru/GC electrode of Ru film thickness around 86 nm. The present study has contributed to exploration of the particular properties of nanostructured Ru film material and to the origin of the abnormal infrared effects.     

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data.     

Quantitative analysis of an organic thin film by XPS,AFM and FT‐IR

We report the characterization of Firpic (iridium(III)bis[4,6‐di‐fluorophenyl]‐pyridinato‐N,C²,]picolinate) organic thin film prepared by vacuum deposition to provide a systematic route to organic film quantification. To analyze the characteristics of thin Firpic films on a Si substrate, various techniques such as XPS, Fourier transform infra‐red (FT‐IR) spectrometer, and atomic force microscopy (AFM) are utilized. The Firpic films remain stable without surface morphological or compositional change during deposition and after exposure to X‐ray irradiation or atmospheric environment, for which qualities these films are believed to be an ideal platform as a pure organic thin film. The monotonic increases in FT‐IR and XPS intensities with film thickness are matching well with each other. In particular, from the XPS intensity analysis, the relative atomic sensitivity factors of the present system, electron attenuation length, and molecular density in the organic thin film can be evaluated. Copyright © 2011 John Wiley & Sons, Ltd.     

Structural properties of lithium thio-germanate thin film electrolytes grown by radio frequency sputtering

In this study, lithium thio-germanate thin film electrolytes have been successfully prepared by radio frequency (RF) magnetron sputtering deposition in Ar gas atmospheres. The targets for RF sputtering were prepared by milling and pressing appropriate amounts of the melt-quenched starting materials in the nLi(2)S + GeS(2) (n = 1, 2, and 3) binary system. Approximately 1 μm thin films were grown on Ni coated Si (Ni/Si) substrates and pressed CsI pellets using 50 W power and 25 mtorr (～3.3 Pa) Ar gas pressures to prepare samples for Raman and Infrared (IR) spectroscopy, respectively. To improve the adhesion between the silicon substrate and the thin film electrolyte, a sputtered Ni layer (～120 nm) was used. The surface morphologies and thickness of the thin films were determined by field emission scanning electron microscopy (FE-SEM). The structural properties of the starting materials, target materials, and the grown thin films were examined by X-ray diffraction (XRD), Raman, and IR spectroscopy.     

The First Recyclable,Nanocrystalline CdS Thin Film Mediated Eco‐benign Synthesis Of Hantzsch 1, 4 Dihyropyridines, 1, 8‐Dioxodecahydroacridine and Polyhydroquinolines derivatives

In the present study, we report a recyclable, nanocrystalline CdS thin film mediated efficient one‐pot, three component synthesis of Hantzsch 1, 4 Dihydropyridine in good yields. The catalyst is also effective for the efficient synthesis of Polyhydroquinoline and 1, 8‐dioxodecahydroacridine derivatives in good to excellent yields. The CdS thin film catalyst was prepared by chemical bath deposition (CBD) technique. The cadmium sulphide thin film was characterized by powder XRD and FT‐IR studies. The average crystallite size (D) was calculated from powder XRD by using Scherrer formula and SEM analysis. The elemental composition of the CdS thin film was established by EDS analysis. The effect of temperature, substituent's, catalyst loading and mole ratio on the reaction was also studied. All the products were thoroughly characterized by ¹H‐NMR, ¹³C‐NMR, FT‐IR, Mass spectral and CHN analysis. A plausible mechanism for the CdS thin film catalyzed synthesis of 1, 4 DHP's is proposed. The heterogeneous catalyst could be easily recovered from the reaction mixture and successively reused at least five times without loss of activity.     

Electrochemical preparation and structural characterization of Co thin films and their anomalous IR properties

Nanometer scale cobalt thin films of different structures and thicknesses supported on glassy carbon were prepared by electrochemical deposition under cyclic voltammetric conditions (denoted nm-Co/GC(n)). The thickness of Co thin films was altered systematically by varying the number (n) of potential cycling within a defined potential range in electrodeposition. Electrochemical in situ scanning tunneling microscopy (STM) and ex situ scanning electron microscopy (SEM) were employed to characterize the surface structure of Co thin films. It has been illustrated that the Co thin films were uniformly composed of Co nanoparticles, whose structure and size varied with increasing n. The structure of nanoparticles inside the Co thin films underwent a transition from bearded nanoparticles to multiform nanoparticles and finally to hexagonal nanosheets, accompanying with an increase of average size. In situ FTIR reflection spectroscopic studies employing CO adsorption as probe reaction revealed that the Co thin films all exhibited anomalous IR properties; that is, along with their different nanostructures they presented abnormal IR effects, Fano-like IR effects, and surface-enhanced IR absorption effects. CO adsorbed on Co thin films dominated by bearded nanoparticles yielded abnormal IR absorption bands; that is, the direction of the bands is inverted completely, with enhanced intensity in comparison with those of CO adsorbed on a bulk Co electrode. The enhancement of abnormal IR absorption has reached a maximal value of 26.2 on the nm-Co/GC(2) electrode. Fano-like IR features, which describe the bipolar IR bands with their positive-going peak on the low wavenumbers side, were observed in cases of CO adsorbed on Co thin films composed mainly of multiform nanoparticles, typically on the nm-Co/GC(8) electrode. IR features were finally changed into surface-enhanced IR absorption as CO adsorbed on the nm-Co/GC(30) electrode, on which the Co thin film is dominated by Co hexagonal nanosheets.     

Investigation of interfacial processes in graphite thin film anodes of lithium-ion batteries by both in situ and ex situ infrared spectroscopy

Graphite thin film anodes with a high IR reflectivity have been prepared by a spin coating method. Both ex situ and in situ microscope FTIR spectroscopy (MFTIRS) in a reflection configuration were employed to investigate interfacial processes of the graphite thin film anodes in lithium-ion batteries. A solid electrolyte interphase layer (SEI layer) was formed on the cycled graphite thin film anode. Ex situ MFTIRS revealed that the main components of the SEI layer on cycled graphite film anodes in 1 mol L -1 LiPF6 /ethylene carbonate + dimethyl carbonate (1:1) are alkyl lithium carbonates (ROCO2 Li). The desolvation process on graphite anodes during the initial intercalation of lithium ion with graphite was also observed and analyzed by in situ MFTIRS.     

In situ STM studies of electrochemical growth of nanostructured Ni films and their anomalous IR properties

We have extended the study of anomalous IR properties, which were initially discovered on nanostructured films of platinum group metals and alloys, to nanostructured films of nickel, a member of the iron group triad, and broadened the fundamental knowledge on this subject. Nanostructured thin films of nickel supported on glassy carbon [nm-Ni/GC(n)] were prepared by electrochemical deposition under cyclic voltammetric conditions, and the thickness of films was altered systematically by varying the number (n) of potential cycling within a defined potential range for electrodeposition. Electrochemical in situ scanning tunneling microscopy (STM) was employed to monitor the electrochemical growth of nanostructured Ni films. These in situ STM images illustrated that, along the increase of the film thickness, Ni films have undergone a transformation from layer structure to island structure and finally to lumpish arris structure. Investigations by in situ FTIR spectroscopy employing adsorbed CO as the probe revealed that these nanostructures of Ni films yield abnormal IR features, Fano-like IR features, and normal IR features, respectively. The IR bands of CO adsorbed on Ni thin films of a layer structure were inverted in their direction and enhanced in their intensity up to 15.5 times on an nm-Ni/GC(4) electrode. The Fano-like IR features, which are defined as a bipolar band with its negative-going peak on the low wavenumber side and its positive-going peak on the high wavenumber side, are observed for the first time on Ni thin films of an island nanostructure, i.e., at the nm-Ni/GC(16) electrode. IR features changed to normal absorption in CO adsorbed on the nm-Ni/GC(25) electrode, i.e., that with lumpish arris nanostructured Ni film of a larger thickness.