Formation of hydronium and methoxonium on Pt(110):: Ab initio determination of spectroscopically observed species

被引:5
作者
Blowers, P [1 ]
Chen, N [1 ]
Masel, RI [1 ]
机构
[1] Univ Illinois, Dept Chem Engn, Urbana, IL 61801 USA
来源
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A | 1999年 / 17卷 / 04期
关键词
D O I
10.1116/1.581885
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
Previously, other researchers have examined the coadsorption of water and hydrogen on Pt(111) with electron energy loss spectroscopy (EELS) and have seen the formation, of a new species. This new species was originally designated to be a ''hydronium'' species, where hydronium referred to H3O+ surrounded by water. However, the formation of H3O+ on platinum has not been widely accepted in the literature because the formation of a bare H3O+ not surrounded by water is not a thermodynamically favored process. In this work, we use abinitio calculations at the MP2(full)/6-31g* level to predict the gas phase frequencies fora host, of water and water-cluster species. These frequencies are compared to high resolution EELS spectra to identify which species form on Pt(110). We find that H5O2+, H7O3+, and H9O4+, fit the EELS spectra quite well, while H3O, H3O-, and H3O+ do not show the right vibrational modes. We have alsb done similar calculations for methanol. Methanol has a higher proton affinity than water, so it seems possible that methanol could also form a positively charged species like methoxonium, CH3OH2+. Once again, EELS spectra show a new species forms on Pt(110). Ab initio calculations are;compared to a high resolution EELS spectrum of hydrogen coadsorbed with methanol on platinum. The most likely species to form here is methoxonium, possibly in a methanol cluster. This conclusion is supported by additional spectra of deuterated species that show the correct isotopic shifts in frequencies predicted by calculations. The conclusion from our study is that ions can form during coadsorption of hydrogen and water and hydrogen and methanol on Pt(110). The ions are probably hydrated, but the further EELS evidence strongly supports ion formation. (C) 1999 American Vacuum Society [S0734-2101(99)19404-1].
引用
收藏
页码:1750 / 1755
页数:6
相关论文
共 17 条
[1]  
BENEDICT WS, 1956, J CHEM PHYS, V24, P1139, DOI DOI 10.1063/1.1742731
[2]   Formation of hydronium and water-hydronium complexes during coadsorption of hydrogen and water on (2x1)Pt(110) [J].
Chen, N ;
Blowers, P ;
Masel, RI .
SURFACE SCIENCE, 1999, 419 (2-3) :150-157
[3]   Evidence for carbocation formation during the coadsorption of methanol and hydrogen on Pt(110) [J].
Chen, N ;
Blowers, P ;
Masel, RI .
SURFACE SCIENCE, 1998, 418 (01) :329-341
[4]   A test of electronegativity equalization during fluorinated ethanol decomposition on Pt(331) [J].
Cong, Y ;
Masel, RI .
SURFACE SCIENCE, 1998, 396 (1-3) :1-15
[5]  
Frisch MJ, 1992, GAUSSIAN 92
[6]   COADSORPTION OF WATER AND HYDROGEN ON PT(100) - FORMATION OF ADSORBED HYDRONIUM IONS [J].
KIZHAKEVARIAM, N ;
STUVE, EM .
SURFACE SCIENCE, 1992, 275 (03) :223-236
[7]   Ab initio calculations of the transition state energy and position for the reaction H+C(2)H(5)R->HH+C(2)H(4)R, with R=H, CH3, NH2, CN, CF3, C5H6: Comparison to Marcus' theory, Miller's theory, and Bockris' model [J].
Lee, WT ;
Masel, RI .
JOURNAL OF PHYSICAL CHEMISTRY, 1996, 100 (26) :10945-10951
[8]   INTRINSIC ACTIVATION BARRIERS FOR A PROTOTYPE HYDROGENOLYSIS REACTION D+C2H6-]DCH3+CH3 IN C-3-NU SYMMETRY [J].
LEE, WT ;
MASEL, RI .
JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (23) :9363-9367
[9]   Ab initio tests of the Marcus equation for the prediction of the position of the transition state for the reaction H+C2H5R→CH4+CH2R with R = H, CH3, NH2, CN, CF3, and C6H5 [J].
Lee, WT ;
Masel, RI .
JOURNAL OF PHYSICAL CHEMISTRY A, 1998, 102 (13) :2332-2341
[10]   CORRECTED ELECTROSTATIC MODEL FOR DIPOLES ADSORBED ON A METAL-SURFACE [J].
MASCHHOFF, BL ;
COWIN, JP .
JOURNAL OF CHEMICAL PHYSICS, 1994, 101 (09) :8138-8151