共查询到20条相似文献,搜索用时 31 毫秒
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Chen QS Sun SG Zhou ZY Chen YX Deng SB 《Physical chemistry chemical physics : PCCP》2008,10(25):3645-3654
CoPt nanoparticles supported on a glassy carbon electrode (denoted as CoPt/GC) were prepared by galvanic replacement reaction between electrodeposited Co nanoparticles and K(2)PtCl(6) solution. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were both employed to characterize the CoPt nanoparticles. It was shown that the CoPt nanoparticles have irregular shapes and most of them exhibit a core-shell structure with a porous Co core and a shell of Pt tiny particles. The composition of the CoPt nanoparticles was analyzed by energy-dispersive X-ray spectroscopy (EDX), which depicts a Co : Pt ratio of ca. 21 : 79. Studies of cyclic voltammetry (CV) demonstrated that CoPt/GC possesses a much higher catalytic activity towards CO and methanol electrooxidation than a nanoscale Pt thin film electrode. In situ FTIR spectroscopic studies have revealed for the first time, that a CoPt nanoparticles electrode exhibits abnormal IR effects (AIREs) for IR absorption of CO adsorbed on it. In comparison with the IR features of CO adsorbed on a bulk Pt electrode, the direction of the IR bands of CO adsorbed on the CoPt/GC electrode is inverted completely, and the intensity of the IR bands has been enhanced up to 15.4 times. The AIREs is significant in detecting the adsorbed intermediate species involved in electrocatalytic reactions. The results demonstrated a reaction mechanism of CH(3)OH oxidation on CoPt/GC in alkaline solutions through evidencing CO(L), CO(M), HCOO(-), CO(3)(2-), HCO(3)(-) and CO(2) as intermediate and product species by in situ FTIRS. 相似文献
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《Electrochemistry communications》2003,5(3):276-282
In situ transmission difference FTIR spectroscopy method was introduced for studying the anodic oxidation of methanol in acid aqueous solution. A minigrid Pt optically transparent thin layer electrode was used as working electrode. This method has the ability to clarify the identity of species involved in the oxidation process both in solution and adsorbed at the surface of electrode. From the results of in situ transmission difference FTIR spectroscopy measurement it was found that HCHO, HCOOH, HCOOCH3 and CH2(OCH3)2 could be formed in the oxidation process of methanol. The final product was CO2. The adsorbed poisonous intermediate CO was detected. It was formed at near 0.6 V and became significant at 0.9 V, where the oxidation current was inhibited. The in situ transmission difference FTIR spectroscopy method is a very convenient, relative simplicity and efficient method for investigating the electrochemical process, and could be as a good candidate for further application. 相似文献
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团聚铂纳米粒子电极在甲醇氧化中的电催化特性 总被引:7,自引:0,他引:7
用H2还原法并以Nafion作为稳定剂合成团聚的Pt纳米粒子,附载于玻碳表面制备电催化剂.透射电子显微镜(TEM)和扫描电子显微镜(SEM)表征结果指出,团聚Pt纳米粒子的平均尺寸约为400 nm.运用电化学循环伏安法(CV)和原位傅立叶变换红外反射光谱(in situ FTIRS)研究甲醇的氧化过程,发现团聚Pt纳米粒子电极具有较高的电催化活性.原位FTIRS研究结果检测到甲醇在所制备的电催化剂上氧化的中间体为线型吸附态CO物种,其红外吸收给出异常红外效应的光谱特征. 相似文献
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D. Malevich J. Li M. K. Chung C. McLaughlin M. Schlaf J. Lipkowski 《Journal of Solid State Electrochemistry》2005,9(5):267-276
We have synthesized colloidal Pt nanoparticles with a mean particle size of 2.6±0.4 nm by reducing PtCl2 dissolved in N,N-dimethylacetamide with t-BuMe2SiH. The latter compound acted both as a reducing agent and a stabilizer of the Pt nanoparticles. Pt nanoparticles were deposited onto the Au substrate and IR reflectance absorption spectroscopy (IRRAS) was applied to investigate CO adsorption and oxidation at the surface of the catalyst. The reactivity of the catalyst covered with Nafion was compared with the reactivity of the catalyst without Nafion. In addition, the reactivity of the colloidal Pt was compared with the reactivity of bulk polycrystalline Pt. We found that CO oxidation proceeds at lower over-potentials at nanoparticles than at polycrystalline Pt. The IRRAS data indicate that the difference in the reactivity may be explained by a different mechanism of the oxidation reaction; Langmuir–Hinshelwood at Pt nanoparticles and island formation and growth at polycrystalline Pt. We have also observed that a film of Nafion slows down the CO oxidation reaction. The IRRAS spectra for CO adsorbed at Pt nanoparticles covered by Nafion were significantly different from the spectra recorded for the nanoparticles in the absence of Nafion. The spectroscopic features suggest that in the presence of Nafion the nanoparticles experience regions of lower and higher proton concentration.This paper is dedicated to Prof. G. Horanyi on the occasion of his 70th birthday and in recognition of his contribution to electrochemistry. 相似文献
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Iva Matolínová Viktor Johánek Josef Mysliveček Kevin C. Prince Tomáš Skála Michal Škoda Nataliya Tsud Mykhailo Vorokhta Vladimír Matolín 《Surface and interface analysis : SIA》2011,43(10):1325-1331
Methanol adsorption on ion‐sputtered Pt(111) surface exhibiting high concentration of vacancy islands and on (2 × 1)Pt(110) single crystal were investigated by means of photoelectron spectroscopy (PES) and thermal desorption spectroscopy. The measurements showed that methanol adsorbed at low temperature on sputtered Pt(111) and on (2 × 1)Pt(110) surfaces decomposed upon heating. The PES data of methanol adsorption were compared to the data of CO adsorbed on the same Pt single crystal surfaces. In the case of the sputtered Pt(111) surface, the dehydrogenation of HxCO intermediates is followed by the CO bond breakage. On the (2 × 1)Pt(110) surface, carbon monoxide, as product of methanol decomposition, desorbed molecularly without appearance of any traces of atomic carbon. By comparing both platinum surfaces we conclude that methanol decomposition occurs at higher temperature on sputtered Pt(111) than on (2 × 1)Pt(110). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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利用电化学衰减全反射原位傅里叶变换红外光谱与微分电化学质谱联用技术,在流动电解池环境以及恒电位条件下研究了Pt电极和Pt电极通过表面电沉积Ru形成的PtRu电极(PtxRuy)上发生的甲醇氧化反应(反应电解质溶液为0.1 mol/L HClO4+0.5 mol/L MeOH). 在0.3-0.6 V(参比电极为可逆氢参比)实验用到的所有电极上,CO是唯一能从红外光谱观察到的与甲醇相关的表面吸附物;在Pt0.56Ru0.44电极上可以观察到CO吸附在Ru原子形成的岛上和CO线式吸附在Pt电极表面红外波段,而其他电极上只能观察到Pt表面上线式吸附的CO;甲醇氧化活性按Pt0.73Ru0.27〉Pt0.56Ru0.44〉Pt0.83Ru0.17〉Pt的顺序递减;在0.5V时,甲醇在Pt0.73Ru0.27电极上的氧化反应的CO2电流效率达到了50%. 相似文献
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CO在载钯分子筛薄膜电极上的增强红外吸收 总被引:1,自引:0,他引:1
以NaY分子筛超笼为微型反应器,通过“瓶中造船”技术合成钯原子簇(Pd13).并首次把粗糙的分子筛薄膜电极引入到电化学原位红外反射光谱研究,发现了一类新的增强红外吸收现象.与金属钯电极相比,CO红外吸收带的谱峰强度显著增加,半峰宽加宽.研究结果表明,这种增强红外吸收取决于钯原子簇的纳米尺度及分子筛超笼的特殊环境. 相似文献
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Yasunari Ikezawa Hiroshi Saito Hisashi Fujisawa Shusuke Tsuji Genjiro Toda 《Journal of Electroanalytical Chemistry》1988,240(1-2)
Carbon monoxide adsorbed on a smooth platinum electrode in the double-layer region was investigated in 1 M HClO4 solution by using in situ polarization modulation IR reflection spectroscopy and an electrochemical oxidation. From the electrochemical oxidation, the adsorbed CO could be distinguished to be comprised of stable and unstable adsorbed CO's. The unstable adsorbed CO constituted about
of the adsorbed CO, and corresponded to linearly adsorbed CO, but the band intensity of the linearly adsorbed CO was not proportional to the amount of unstable adsorbed CO. The stable adsorbed CO constituted about
; it was one-site adsorbed, and was an IR-inactive species. It is presumed that the IR-inactive species is adsorbed on two Pt atoms with the C-O axis parallel to the electrode surface and one of the Pt atoms bound to two CO molecules. 相似文献
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Lyubomira Ivanov Jessica Rosenholm Tanya Tsoncheva Mika Linden Daniela Paneva Ivan Mitov 《Reaction Kinetics and Catalysis Letters》2008,95(2):329-336
Iron modified NH2- or COOH- functionalized SBA-15 is characterized by XRD, N2-physisorption, TPR-TG, FTIR, M?ssbauer spectroscopy and methanol decomposition. The material obtained from COOH-functionalized
silica exhibits the highest catalytic activity. 相似文献
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A. V. Rassolov P. V. Markov G. O. Bragina G. N. Baeva D. S. Krivoruchenko I. S. Mashkovskii I. A. Yakushev M. N. Vargaftik A. Yu. Stakheev 《Kinetics and Catalysis》2016,57(6):859-865
The formation of Pd–Ag nanoparticles deposited from the heterobimetallic acetate complex PdAg2(OAc)4(HOAc)4 on α-Al2O3, γ-Al2O3, and MgAl2O4 has been investigated by high-resolution trans-mission electron microscopy, temperature-programmed reduction, and IR spectroscopy of adsorbed CO. The reduction of PdAg2(OAc)4(HOAc)4 supported on γ-Al2O3 and MgAl2O4 takes place in two steps (at 15–245 and 290–550°C) and yields Pd–Ag particles whose average size is 6–7 nm. The reduction of the Pd–Ag catalyst supported on α-Al2O3 occurs in a much narrower temperature range (15–200°C) and yields larger nanoparticles (~10–20 nm). The formation of Pd–Ag alloy nanoparticles in all of the samples is demonstrated by IR spectroscopy of adsorbed CO, which indicates a marked weakening of the absorption band of the bridged form of adsorbed carbon monoxide and a >30-cm–1 bathochromic shift of the linear adsorbed CO band. IR spectroscopic data for PdAg2/α-Al2O3 suggest that Pd in this sample occurs as isolated atoms on the surface of bimetallic nanoparticles, as is indicated by the almost complete absence of bridged adsorbed CO bands and by a significant weakening of the Pd–CO bond relative to the same bond in the bimetallic samples based on γ-Al2O3 and MgAl2O4 and in the monometallic reference sample Pd/γ-Al2O3. 相似文献
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《Comptes Rendus Chimie》2014,17(7-8):717-724
SBA-15-based solids combining semiconductive oxides (Sn and In) and noble metal (Pt) were prepared by an incipient wet impregnation method in order to obtain materials for gas sensing. The materials were characterized by XRD, BET adsorption, SEM, and TEM. The BET analysis allowed obtaining details about the specific surface areas, pore size, and modifications due to the indium and/or tin oxides followed by the Pt deposition. XRD data revealed that In2O3 did not enter the mesopores of SBA-15, preventing also the entrance of the Pt nanoparticles in the mesopores. On the other hand, SnO2 nanoparticles further doped with Pt could enter the mesoporous network, affording a SBA-15 material loaded with SnO2 and very small Pt nanoparticles with high dispersion. Tablets obtained by pressing the modified SBA-15 were tested as sensitive materials for propene and hydrogen detection. 相似文献
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Martin Heinen Yan‐Xia Chen Prof. Zenonas Jusys Dr. Rolf Jürgen Behm Prof. 《Chemphyschem》2007,8(17):2484-2489
The room temperature desorption and exchange of CO in a saturated CO adlayer on a Pt electrode, at potentials far below the onset of oxidation, was investigated by isotope labeling experiments, using a novel spectroelectrochemical setup, which allows the simultaneous detection of adsorbed species by in situ IR spectroscopy and of volatile (side) products and reactants by online mass spectrometry under controlled electrolyte flow conditions. Time‐resolved IR spectra show a rapid, statistical exchange of pre‐adsorbed 13COad by 12COad in 12CO containing electrolyte; mass spectrometric data reveal first‐order exchange kinetics, with the rate increasing with CO partial pressure. The increasing COad desorption rate in equilibrium with a CO containing electrolyte is explained by a combination of an increasing COad coverage upon increasing the CO pressure, and a decrease of the CO adsorption energy with coverage, due to repulsive COad–COad interactions. 相似文献
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P. V. Markov G. O. Bragina G. N. Baeva O. P. Tkachenko I. S. Mashkovskii I. A. Yakushev M. N. Vargaftik A. Yu. Stakheev 《Kinetics and Catalysis》2016,57(5):617-624
The formation of Pd–In catalysts synthesized from the heteronuclear acetate complex PdIn(CH3COO)5 was studied by temperature-programmed reduction, electron microscopy, IR spectroscopy of adsorbed CO and hydrogen temperature-programmed desorption (H2-TPD). IR spectroscopy of adsorbed CO and H2-TPD confirmed the formation of bimetallic Pd–In nanoparticles. It was found that the Pd–In nanoparticle surface contains predominantly Pd atoms separated from one another by indium atoms, which is evidenced by the disappearance of the CO band shift resulting from the lateral dipole–dipole interaction between adsorbed CO molecules and by a significant decrease in the band intensity of CO adsorbed in bridged form. Almost complete inhibition of palladium hydride (PdHx) provides additional evidence of the formation of Pd–In bimetallic particles. 相似文献
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G. García J. Silva-Chong J. L. Rodríguez E. Pastor 《Journal of Solid State Electrochemistry》2014,18(5):1205-1213
The electrochemical behavior of acetaldehyde on palladium and platinum electrodes in acidic media was comparatively studied by means of differential electrochemical mass spectrometry (DEMS) and in situ Fourier transform infrared spectroscopy (FTIRS) combined with cyclic voltammetry. It was observed that acetaldehyde decomposition depends on the catalyst material, applied potential, and reactant concentration. Additionally, it was detected that acetaldehyde adsorbs and dissociates at potentials lower than 0.60 V vs RHE, producing methane and adsorbed CO on Pd; while C2-species, CHx and COad are formed on Pt. Besides carbon dioxide, acetic acid and adsorbed acetate were observed at E?>?0.6 V, and their contribution increased with acetaldehyde concentration. Differences between Pt and Pd in potential dependence of the products and intermediates were established. Calibration of the mass spectrometer, together with the use of labeled acetaldehyde and IR spectra, allows establishment of the nature of adsorbed species and products for both Pt and Pd at different potentials, elucidating global reaction pathways for acetaldehyde on these two noble metals. 相似文献
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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 总被引:2,自引:1,他引:1
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 . 相似文献