Impurity Effect on Surface Diffusion: CO/S/Ni(110)

Xiao, Xudong; Xie, Yujun; Jakobsen, C.; Galloway, Heather C.; Salmerón, Miquel; Shen, Y. R.

doi:10.1103/physrevlett.74.3860

Cited by 38 publications

(21 citation statements)

References 20 publications

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“…[51][52][53][54] We note that surface mobility of hydrogen can decrease by a factor of ϳ60 as the surface carbon coverage was increased from C =0 to C = 0.42 ML at T = 300 K. 52 However, in our case, the amount of impurities was below the AES sensitivity. Comparing our measured diffusion coefficient D with the extrapolated value from QHAS results, we see a difference of more than four orders of magnitude (see Fig.…”

Section: Comparison With Previous Resultsmentioning

confidence: 56%

Step effects and coverage dependence of hydrogen atom diffusion onPt(111)surfaces

2004

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Step effects on surface diffusion of hydrogen on stepped Pt͑111͒ have been studied by linear optical diffraction technique over a temperature range from 90 to 150 K. Diffusion anisotropy on stepped Pt͑111͒ surfaces has been observed: the unexpected enhanced diffusion perpendicular to steps cannot be explained within the lattice gas model on stepped substrates, indicating a nonlocal and directional step effect. The coverage-dependent diffusion coefficient on flat Pt͑111͒ surface was also measured over a wide coverage range from 0.1 to 0.8 ML. They were analyzed within the framework of the lattice gas model using quasichemical approximation, indicating that H-H repulsive interaction can significantly affect the energy of saddle point as well as that at the adsorption sites.

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Section: Comparison With Previous Resultsmentioning

confidence: 56%

Step effects and coverage dependence of hydrogen atom diffusion onPt(111)surfaces

2004

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“…We have chosen to use sulfur which is a well-known inhibitor or poison to active sites in general 23,27,28 due to its strong interaction with undercoordinated sites. 29,30 In particular for the methanation reaction over ruthenium, Goodman and co-workers have shown that less than 5% of a monolayer of sulfur was needed to poison up to 70% of the methanation activity on a Ru(001) crystal, see ref. [31][32][33] and references therein.…”

Section: Introductionmentioning

confidence: 99%

Is the methanation reaction over Ru single crystals structure dependent?

Vendelbo

Johansson

Nielsen

et al. 2011

Phys. Chem. Chem. Phys.

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The influence of monoatomic steps and defects on the methanation reaction over ruthenium has been investigated. The experiments are performed on a Ru(0 1 54) ruthenium single crystal, which contains one monoatomic step atom for each 27 terrace atoms. The methanation activity is measured at one bar of hydrogen and CO in a high pressure cell, which enables simultaneous measurements of the local reactivity of the well defined single crystal surface and the global reactivity of the entire crystal and its auxiliary support. By adding sulfur we observe that the measured activity from the well defined stepped front-side of the crystal is poisoned faster than the entire crystal containing more defects. We also observe that additional sputtering of the well-defined front-side increases the reactivity measured on the surface. Based on this, we conclude that the methanation reaction takes place on undercoordinated sites, such as steps and kinks, and that the methanation reaction is extremely structure dependent. Simulations of the flow, temperature, and product distributions in the high pressure cell are furthermore presented as supplementary information.

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“…Since the period of the coverage grating is on the micron scale so it contains many steps, step effects can appear in our measurements if they are important. 13 By aligning the onedimensional adsorbate grating parallel or perpendicular to the steps, diffusion anisotropy can be measured.…”

Section: Introductionmentioning

confidence: 99%

Diffusion of CO on Pt(111) studied by an optical diffraction method

Xiao

DiNardo

et al. 1998

Phys. Rev. B

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We have measured the diffusion of CO on flat and stepped Pt͑111͒ surfaces using the linear optical diffraction method from an adsorbate grating. Measurements over a wide range of temperatures ͑133-313 K͒ and CO coverages ͑0.1-0.67 ML͒ indicate Arrhenius behavior with diffusion activation energies of 3.0-4.7 kcal/mol and 7.3-7.9 kcal/mol for flat and stepped surfaces, respectively. Comparisons of our measurements on flat and stepped ͑defected͒ surfaces with previous experiments by various groups using various techniques resolves several discrepancies and illustrates the importance of defect-induced effects on variations in measured diffusion parameters. ͓S0163-1829͑98͒09631-3͔

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Impurity Effect on Surface Diffusion: CO/S/Ni(110)

Cited by 38 publications

References 20 publications

Step effects and coverage dependence of hydrogen atom diffusion onPt(111)surfaces

Step effects and coverage dependence of hydrogen atom diffusion onPt(111)surfaces

Is the methanation reaction over Ru single crystals structure dependent?

Diffusion of CO on Pt(111) studied by an optical diffraction method

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