欢迎访问《电化学(中英文)》期刊官方网站,今天是
研究论文

Pt电极上CO的同位素取代吸附机理研究

  • 梁桑梓 ,
  • 刘少雄 ,
  • 廖玲文 ,
  • 陶骞 ,
  • 康婧 ,
  • 陈艳霞
展开
  • 中国科技大学化学物理系,合肥微尺度物质科学国家实验室(筹);

收稿日期: 2010-08-28

  修回日期: 2010-08-28

  网络出版日期: 2010-08-28

The Mechanism of ~(13)CO_(ad)/~(12)CO Isotope Exchange at Pt Electrode,a Combined Study by Electrochemical in-situ Infrared Spectroscopy and Dipole-dipole Coupling Analysis

  • LIANG Sang-zi ,
  • LIU Shao-xiong ,
  • LIAO Ling-wen ,
  • TAO Qian ,
  • KANG Jing ,
  • CHEN Yan-xia
Expand
  • ( Hefei National Laboratory for Physical Sciences at Microscale,Department of Chemical Physics, University of Science and Technology of China,Hefei 230026,China

Received date: 2010-08-28

  Revised date: 2010-08-28

  Online published: 2010-08-28

摘要

本文依据偶极耦合理论和相干势近似方法,合理选择粗糙电极上吸附分子的频率分布函数、一氧化碳(CO)吸附层的结构参数以及偶极耦合作用常数,对13CO/12CO同位素取代过程记录的红外光谱进行了拟合.研究发现,只有在拟合过程中引入低频CO分子优先取代,就可成功地模拟整个同位素取代过程的红外光谱随表面吸附的13CO/12CO组分的变化,并由此提出了吸附驱动的脱附机理,COad的脱附不是热激发脱附,而是吸附到表面的CO分子为其邻近位置COad的脱附提供能量.伸缩振动频率较低的COad处于台阶或缺陷位等较开阔的位置(尽管其吸附能较高),周围有较大的空间,利于来自溶液的CO分子的吸附,因此在台阶或缺陷位优先发生同位素的取代.

本文引用格式

梁桑梓 , 刘少雄 , 廖玲文 , 陶骞 , 康婧 , 陈艳霞 . Pt电极上CO的同位素取代吸附机理研究[J]. 电化学, 2010 , 16(3) : 324 -333 . DOI: 10.61558/2993-074X.2054

Abstract

In this contribution,we have analyzed the IR spectra of saturated CO adlayer at rough Pt film electrode as a function of fractional surface coverage of 13COad/12COad recorded during 13COad /12CO isotope exchange process according to dipole-dipole coupling theory and coherent potential approximation. By properly choosing the parameters of adlayer structure and dipole-dipole coupling interaction under coherent potential approximation, we demonstrated that we can successfully simulate the IR spectra as a function of the surface coverage of CO adlayer at rough Pt film electrodes by assuming that COad molecules with low C—O stretching frequencies are dis- placed preferentially during the 13COad/12CO isotope exchange. From this,we proposed that 13COad/12CO isotope exchange proceeds via adsorption assisted desorption mechanism,i. e. ,the adsorption energy released from the incoming COad(to be adsorbed) provides the activation energy for its neighboring COad molecules to be desorbed. The fact that those COad adsorbs at defects or steps (with low C—O stretching frequencies,although with slightly higher adsorption energy than those at terrace sites) are preferentially displaced,comparing to those COad species sitting at terraces,is due to the fact that the defects sites are more open and have much larger free space for the incoming molecules to be adsorbed.

参考文献

[1]Heinen M,Chen Y X,Jusys Z,et al.CO adsorption ki-netics and adlayer build-up studied by combined ATR-FTIR spectroscopy and on-line DEMS under continuous flow conditions[J].Electrochimica Acta,2007,53:1279. [2]Wieckowski A,Rubel M,Gutiérrez C.Reactive sites in bulk carbon monoxide electro-oxidation on oxide-free platinum(111)[J].Journal of Electroanalytical Chemis-try,1995,382:97. [3]Watanabe S,Kinomoto Y,Kitamura F,et al.An infrared study of CO adsorbed on Pt(100)and Pt(110)elec-trodes:Dynamic aspects of CO at reconstructed surfaces[J].Journal of Electron Spectroscopy and Related Phe-nomena,1990,(54/55):1205. [4]Roth J D,Weaver M J.The electrooxidation of carbon monoxide on platinum as examined by surface infrared spectroscopy under forced hydrodynamic conditions[J].Journal of Electroanalytical Chemistry,1991,307:119. [5]Wasileski S A,Koper M T M,Weaver M J.Field-de-pendent chemisorption of carbon monoxide on platinum-group(111)surfaces:Relationships between binding energetics,geometries,and vibrational properties as as-sessed by density functional theory[J].The Journal of Physical Chemistry B,2001,105:3518. [6]Acres G J K,Frost J C,Hards G A,et al.Electrocata-lysts for fuel cells[J].Catalysis Today,1997,38:393. [7]Steele B C H,Heinzel A.Materials for fuel-cell technol-ogies[J].Nature,2001,414:345. [8]Brandon N P,Skinner S,Steele B C H.Recent advances in materials for fuel cells[J].Annual Review of Materi-als Research,2003,33:183. [9]Harrick N J.Internal reflection spectroscopy[M],Ossin-ing Harrick S-cientific Products,1967. [10]Kunimatsu K,Seki H,Golden W G,et al.Electrode/e-lectrolyte interphase study using polarization modulated FTIR reflection-absorption spectroscopy[J].Surf Sci,1985,158:596. [11]Kunimatsu K,Seki H,Golden W G,et al.Carbon mon-oxide adsorption on a platinum electrode studied by po-larization-modulated FT-IR reflection-absorption spec-troscopy:II.Carbon monoxide adsorbed at a potential in the hydrogen region and its oxidation in acids[J].Langmuir,1986,2:464. [12]Iwasita T,Nart F C,Rodes A,et al.Vibrational spec-troscopy at the electrochemical interface[J].Electro-chimica Acta,1995,40:53. [13]Sun S G,Lipkowski J,Ross P N(Eds.).Electrocataly-sis[M].New York,Wiley-VCH,1998. [14]Miki A,Ye S,Osawa M.Surface-enhanced IR absorp-tion on platinum nanoparticles:an application to real-time monitoring of electrocatalytic reactions[J].Chem Commun,2002,1500 [15]Osawa M.Handbook of vibrational spectroscopy[M].Chi-chester:Wiley,2002.785-799. [16]Chen Y X,Miki A,Ye S,et al.Formate,an active in-termediate for direct oxidation of methanol on Pt elec-trode[J].Journal of the American Chemical Society,2003,125:3680. [17]Zhou Z Y,Lin S C,Chen S P,et al.In situ step-scan time-resolved microscope FTIR spectroscopy working with a thin-layer cell[J].Electrochem Commun,2005,7:490. [18]Chen Y X,Heinen M,Jusys Z,et al.Kinetics and mechanism of the electrooxidation of formic acid-spec-troelectrochemical studies in a flow cell[J].Angew Chem Int Edit,2006,45:981. [19]Chen Y X,Ye S,Heinen M,et al.Application of in-situ attenuated total reflection-Fourier transform infrared spectroscopy for the understanding of complex reaction mechanism and kinetics:Formic acid oxidation on a Pt film electrode at elevated temperatures[J].The Journal of Physical Chemistry,2006,110:9534. [20]Tian Z Q,Ren B,Li J F,et al.Expanding generality ofsurface-enhanced Raman spectroscopy with borrowing SERS activity strategy[J].Chem Commun,2007:3514. [21]Persson B N J,Ryberg R.Vibrational interaction be-tween molecules adsorbed on a metal surface:The di-pole-dipole interaction[J].Physical Review B,1981,24:6954. [22]Severson M W,Stuhlmann C,Villegas I,et al.Dipole-dipole coupling effects upon infrared-spectroscopy of compressed electrochemical adlayers-application to the Pt(111)/Co system[J].J Chem Phys,1995,103:9832. [23]Persson B N J.Absorption of phonons by molecules adsorbed on metal surfaces[J].Solid State Communi-cations,1979,30:163. [24]Chang S C,Weaver M J.Coverage-dependent dipole coupling for carbon-monoxide adsorbed at ordered plat-inum(111)-aqueous interfaces-structural and electro-chemical implications[J].J Chem Phys,1990,92:4582. [25]Heinen M,Chen Y X,Jusys Z,et al.Room temperature COad desorption/exchange kinetics on pt electrodes—A combined in situ IR and mass spectrometry study[J].Chemphyschem,2007,8:2484. [26]Severson M W,Russell A,Campbell D,et al.Vibration-al coupling in carbon monoxide adlayers on a platinum electrode[J].Langmuir,1987,3:202. [27]Hollins P,Pritchard J.Infrared studies of chemisorbed layers on single crystals[J].Progress in Surface Sci-ence,1985,19:275. [28]Geng B,Liu S,Cai J,et al.The mechanism and kinet-ics of cyanide-assisted carbon monoxide desorption from Pt electrodes:An infrared spectroscopic study[J].The Journal of Physical Chemistry C,2009,113:10326. [29]Geng B,Cai J,Liang S,et al.Temperature effects on CO adsorption/desorption at Pt film electrodes:an electrochemical in situ infrared spectroscopic study[J].Physical Chemistry Chemical Physics,accept,2010,36:10888.
文章导航

/