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1.
It was demonstrated that adsorbed CO is obtained from the reduction of NaHCO3 solution when Pt(100), Pt(110), disordered Pt(111) and polycrystalline electrodes are employed. Reduction of CO2 coming from the dissociation of the hydrogencarbonate anion is proposed as the reaction that produces CO. By using Fourier transform infrared spectroscopy, linear and multi-bonded CO were detected on polycrystalline platinum electrodes. The shape of the band associated with linearly adsorbed CO is monopolar as a consequence of the partial overlapping, at lower wavenumbers, of the absolute bands at both potentials (0.05 and 0.35 V). 相似文献
2.
Pt(111)表面上一氧化碳的吸附与氧化反应1)刘金尧(清华大学一碳化工国家重点实验室北京100084)XuMZaeraF(DepartmentofChemistryUniversityofCaliforniaRiversideCA92521)关键词... 相似文献
3.
We investigated the 3d5/2 core-level binding energy of Ru in Ru nanoislands spontaneously deposited on a Pt(111) electrode [Pt(111)/Ru], and the binding energies of 3d5/2 iodine and 1s CO adsorbed on Pt(111)/Ru by the use of X-ray photoelectron spectroscopy. Both iodine and CO were used as surface probes of the electronic properties of Pt(111)/Ru. Little difference was found in the binding energy of Ru in Pt(111)/Ru and in Ru(0001). However, the addition of Ru to Pt(111) induces major changes in the core-level binding energies of chemisorbed iodine and CO as referenced to those adsorbed on Ru(0001). We conclude that the iodine 3d5/2 and CO 1s C core levels experience higher electronic charge on Pt(111)/Ru than on Ru(0001), suggesting a charge transfer from Pt to Ru, or to a Ru-I surface molecule within the deposit. The charge transfer from Pt to Ru is in agreement with the result of previous in situ electrochemical NMR investigations [P.K. Babu, H.S. Kim, A. Wieckowski, E. Oldfield (2003) J. Phys. Chem. B 107:7595] and confirms the general trend of reduction in the density of states of Pt due to alloying with Ru [J. McBreen, S. Mukerjee (1995) J. Electrochem. Soc. 142:3399]. Theoretical calculations are in progress to further interpret the origin of the binding-energy shifts observed in this study.Dedicated to Zbigniew Galus on the occasion of his 70th birthday 相似文献
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5.
Sb在Pt(100),Pt(110),Pt(111)及Pt(320)上不可逆吸附的电化学特性 总被引:3,自引:0,他引:3
研究了Sb在Pt(1 0 0 ) ,Pt(1 1 0 ) ,Pt(1 1 1 )和Pt(32 0 )单晶面上不可逆吸附的电化学特性 .发现当扫描电位的上限Eu≤ 0 .45V时 ,Sbad可以稳定地吸附在Pt(1 0 0 ) ,Pt(1 1 0 )和Pt(1 1 1 )表面 ,而Sbad在Pt(32 0 )表面稳定的电位较低 ,为Eu≤ 0 .40V .从饱和吸附Sb的铂单晶电极出发 ,通过改变电位扫描上限Eu 和电位扫描圈数可以获得不同Sb覆盖度 (θSb)的电极 .根据Sb和H在铂单晶电极表面共吸附的定量数据 ,对Sb在不同铂单晶面上饱和吸附的模型进行了初步探讨 . 相似文献
6.
Masaru Sato Kaoru Suzuki Hirofumi Asano Masato Sekino Yasushi KawataYoichi Habata Sadatoshi Akabori 《Journal of organometallic chemistry》1994,470(1-2):263-269
Molecular structures of (triphenylphosphine) [1,1′-bis-(methylthio)ferrocene-S,S′,Fe]Pt(BF4)2 (1), (1,5,9-trithia[9]ferrocenophane-S,S′,S″,Fe)Pd(BF4)2 (2), and (acetonitrile)(1,4,7-trithia[7]ferrocenophane-S,S′,S″,Fe)Pd(BF4)2 (3) were determined by X-ray analyses. The Pt in 1 and the Pd atom in 2 have a somewhat distorted square-planar geometry including the Fe atom of the ferrocene moiety, while the Pd atom in 3 is coordinated by one equivalent of acetonitrile and takes a distorted tetragonal-pyramidal geometry. The distances of the Fe---M bond (M = Pd, Pt) in 1–3 are 2.851(2), 2.827(2), and 3.0962(8) Å, respectively. Cyclic voltammetry of 1–3 gave no reversible wave, but afforded some information supporting the presence of a dative bond. 相似文献
7.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(42):13063-13067
Graphene is a promising candidate for an ideal membrane material. Its ultralow (one‐atomic) thickness potentially provides high permeation and at the same time high selectivity. Here, it is shown that these properties can be used to create a confined, two‐dimensional electrochemical environment between a graphene layer and a single‐crystal Pt(111) surface. The well‐defined fingerprint voltammetric characteristics of Pt(111) provide an immediate information about the penetration and intercalation of ions into the confined space. These processes are shown to be highly selective. 相似文献
8.
We report here a study, using cyclic voltammetry and FTIRS, of NO irreversibly adsorbed on a cyanide-modified Pt(111) electrode. NO adlayers were formed by immersion of the cyanide-modified Pt(111) electrode in an acidic solution of KNO(2). The behaviour of NO adsorbed on the cyanide-modified electrode is very similar to that of NO on the clean Pt(111) surface, suggesting that adsorbed cyanide (saturation coverage theta(CN) = 0.5) behaves simply as a third body, blocking some of the surface sites but leaving the free Pt sites unaffected. Comparison of the voltammetric profile for NO electroreduction on Pt(111) and on cyanide-modified Pt(111) electrodes has allowed us: (i) to confirm that the reduction of three-fold hollow NO and atop NO on Pt(111) electrodes occurs in two distinct reduction peaks, as previously proposed by Rosca et al. (Langmuir, 2005, 21, 1448); (ii) to suggest that the reduction of irreversibly adsorbed NO layers on Pt electrodes can proceed through two possible paths, one involving an EE mechanism in which the rate-determining step (rds) is an Eley-Rideal reaction, with a direct proton transfer from the solution to adsorbed NO, and the other involving an EC mechanism in which the rds is a Langmuir-Hinshelwood reaction of adsorbed NO with adsorbed H. The availability of adsorbed hydrogen determines which path is followed by the reaction; (iii) to identify the smallest atomic ensemble for the reduction of NO on Pt as being composed of two adjacent Pt atoms. 相似文献
9.
《Journal of Electroanalytical Chemistry》1986,199(1):187-200
Electrochemical adsorption-desorption of hydrogen has been shown to be a structure-sensitive reaction. The influence of the crystallographic surface structure on this process is typically represented by the voltammogram of such a surface in contact with 0.5 M H2SO4 solution.For a given crystallographic plane, the voltammetric profile shows several peaks which are ascribed to various H adsorption states. Defined polarization programmes, applied to such electrodes, changed in a controlled way the population of each state with the possibility of inducing new ones.These transformations in the shape of the Pt (100) voltammogram in the hydrogen adsorption region suggest that the surface undergoes reconstruction due to hydrogen adsorption above 0.3 of a monolayer. The combined effect of low oxygen coverage with high hydrogen coverage induces a new type of voltammogram. At least four types of voltammogram have been observed for this orientation, each related to a particular surface structure which remains unknown in the present state of knowledge. This behaviour is in agreement with the known behaviour of this surface in contact with the gas phase at low pressure whose surface structure depends on the presence or not of an adsorbate such as hydrogen and on thermal treatment. This work gives preliminary evidence for the existence of possibilities of passing reversibly, by an electrochemical route, from one surface structure to another.For the Pt (111) surface, only one ordered state and a disturbed state with a different degree of disorder are observed. There is no known electrochemical possibility of passing reversibly from one state to the other; the transformation always occurs from the ordered to the disordered state.Comparison of these various voltammograms with that of a polyoriented model surface represented by a sherical Pt single crystal suggest that for both orientations the most strongly bonded hydrogen states are directly connected with the presence of two-dimensional long-range ordered domains on these low index surfaces. 相似文献
10.
Thiophene adsorption on the(111) surfaces of Pd and Pt have been investigated by density functional theory.The results indicate that the adsorption at the hollow sites is the most stable.To our interest,the molecular plane of thiophene ring is distorted with C=C bond being elongated to 1.450 and C-C bond being shortened to 1.347 ,and the C-H bonds tilt 13.91~44.05o away from this plane.Furthermore,analysis on population and density of states verified the calculated adsorption geometries.Finally,charge analysis suggests that thiophene molecule is an electron acceptor,reflecting the interaction between the lone pair of sulfur and the d-orbitals of metal. 相似文献
11.
Presented are sequential images of CO on Pt(111), observed with electrochemical scanning tunneling microscopy, during its electrochemical preoxidation process. In the course of the well-known phase transition from the (2 x 2)-3CO-alpha structure to the (radical 19 x radical 19)R23.4 degrees-13CO structure, various structures were observed: (2 x 2)-3CO-beta (Chem. Comm. 2006, 2191-2193), (1 x 1)-CO, and (radical 13 x radical 13)R46.1 degrees-9CO. Based on an analysis of the populations of the structures averaged over imaging time and imaged location at the preoxidation potential range (0-0.25 V vs Ag/AgCl), the structures of CO domains changed sequentially in the order of (2 x 2)-3CO-alpha, (2 x 2)-3CO-beta, (1 x 1)-CO, (radical 13 x radical 13)R46.1 degrees-9CO, and (radical 19 x radical 19)R23.4 degrees-13CO as the potential shifted from 0 to 0.25 V. Such a sequential structural change demonstrates that the structures of (2 x 2)-3CO-beta, (1 x 1)-CO, and (radical 13 x radical 13)R46.1 degrees-9CO are transient ones during the preoxidation of CO on Pt(111). Discussed are the transient structures in terms of various aspects, such as the absence of CO in solution and the origin of compressed structures. 相似文献
12.
利用羧基取代法, 通过化合物Pt4(OCOCH3)8与过量的丙烯酸作用合成了配合物Pt4(OCOCH3)4(OCOCH=CH2)4. 晶体结构研究结果表明, 化合物Pt4(OCOCH3)8中的4个乙羧基能够被烯丙羧基有规律地选择性替换, 从而形成一个含双键的对称铂配合物. 利用Si—H与不饱和键的加成性质将该配合物嫁接到氢化n型单晶硅(111)表面, 发现配合物Pt4(OCOCH3)4(OCOCH=CH2)4除了能嫁接到单晶硅表面外, 还能在n型单晶硅表面进行自组装而形成许多岛状纳米粒子, 这种组装体系具有良好的热稳定性和一定的抗酸性. 相似文献
13.
Laliberté MA Lavoie S Hammer B Mahieu G McBreen PH 《Journal of the American Chemical Society》2008,130(16):5386-5387
Trifluoroacetophenone (TFAP) forms C O...H-C bonded dimers and trimers at room temperature on Pt(111). It is proposed that these systems mimic the prochiral carbonyl-chiral modifier interaction in the enantioselective hydrogenation of TFAP on cinchona-modified Pt catalysts. That is, the activation of TFAP in homomolecular assemblies at racemic sites is expected to be roughly the same as in the diastereomeric complex formed at chiral sites. This interpretation suggests a reason why alpha-phenyl ketones do not display a strong measured rate enhancement effect in the Orito reaction. 相似文献
14.
Presented are two newly observed adstructures of adsorbed CO onto Pt(111), (2 x 2)-3CO-beta and (2 x 2)-4CO, observed during the structural evolution from the well-known (2 x 2)-3CO-alpha structure to the (square root 19 x square root 19)-13CO structure. 相似文献
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16.
《Journal of Coordination Chemistry》2012,65(20):3575-3584
To further understand the effect of water as a solvent in organometallic reactions, the lability of η2-alkenes coordinated to platinum(II) phosphine complexes has been studied in water and chloroform as a comparison of solvent effects on the exchange kinetics and alkene complex stability. 1H NMR techniques with both deuterated chloroform and a deuterium oxide/deuterated methanol mixture as solvent systems were used at temperatures as low as ?50°C. Reaction of cis-PtCl2L(η2-C3H6) [L?=?PPh3 (triphenylphosphine) (1a), TPPTS (tris(m-sulfonatophenyl)phosphine) 1b] with ethylene to form cis-PtCl2L(η2-C2H4) (2?a, b) was observed with dependence on the rate by starting platinum complex and ethylene. The role of water on this reaction, as well as its effect on the equilibrium, will be discussed. The equilibrium constant shows preference for coordination of ethylene and the temperature dependence indicates the reaction is entropy controlled. 相似文献
17.
ITO上电沉积Pd的成核机理及电催化性质 总被引:1,自引:0,他引:1
采用循环伏安技术和计时电流技术, 研究了ITO上电沉积Pd的过程, 发现Pd在ITO表面的电沉积是过电位成核且为不可逆的扩散控制过程; 根据Cottrell方程计算得到[PdCl4]2-的扩散系数为2.19×10-5 cm2/s; 根据Scharifker的理论模型, 归一化处理电流-时间曲线, 与理论成核曲线对照, 判断Pd 的成核机理. 通过场发射扫描电子显微镜(FESEM)对Pd 的形貌进行分析, 讨论了沉积电位和沉积时间对Pd纳米粒子形貌的影响. 用X射线粉末衍射(XRD)对Pd纳米粒子进行结构分析, 并在0.5 mol/L H2SO4溶液中研究了其电化学性质及在碱性条件下乙醇分子的电催化性质. 相似文献
18.
本文研究BMIPF6离子液体中Au(111)和Pt(111)表面Ge的电沉积行为. 循环伏安法测试结果表明,在含0.1 mol·L-1 GeCl4的BMIPF6溶液Au(111)和Pt(111)表面均有两个与Ge沉积过程相关的还原峰. 第一个还原峰包含了Ge4+还原成Ge2+及Ge的欠电位沉积,第二个还原峰对应Ge的本体沉积. 现场扫描隧道显微镜研究结果表明,Ge在Au(111)和Pt(111)表面均有两层欠电位沉积. 第一层欠电位沉积厚度约为0.25 nm、形貌平整、带有缝隙的亚单层结构. 第二层欠电位沉积形貌相对粗糙的点状团簇结构. 该欠电位沉积过程伴随表面合金化. 相似文献
19.
The self-assembly of thiol molecules from ethanolic solution on Au(111) depends significantly on the electrode potential.
Especially at cathodic potentials, chemisorption of thiol molecules and the development of the highly ordered structure are
slowed down significantly. At potentials near the point of zero charge, first a disordered thiol film of already high thiol
density is formed, and then domains of the highly ordered phase develop and grow together. At cathodic potentials, first a
disordered film of very low density of predominant flat adsorbed thiol molecules is formed; the formation of ordered domains
takes time three orders of magnitude longer than at potentials near the point of zero charge.
Received: 27 May 1997 / Accepted: 8 September 1997 相似文献
20.
《中国化学快报》2020,31(9):2478-2482
High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy. In this work, we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon (Pt NDs). Owing to the large electrochemically active area and the exposed (111) facet of Pt, Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈ 22 mV/dec in acidic media. In addition, the hydrogen yield of Pt NDs is 30%–45% larger than that of commercial Pt/C at the same Pt loadings. Moreover, Pt NDs exhibits excellent long-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production, while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance. Considering the superiority of catalytic activity and stability, this Pt NDs present great potentiality towards practical hydrogen production application. 相似文献