Low and high coverage determinations of the rate of carbon monoxide adsorption and desorption from Pt(110)

Fair, J. A.; Madix, Robert J.

doi:10.1063/1.440500

Cited by 91 publications

(27 citation statements)

References 12 publications

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“…Figure 6 shows a high-temperature first-order desorption peak (β 1 ) at 490 K for all coverages, with a second peak evolving at 398 K (β 2 ). This behavior is consistent with literature [37][38][39]. Using the Redhead equation assuming a frequency prefactor of ν = (4.5 ± 1.5) × 10 14 s −1 (averaged from values of ν = 6 × 10 14 s −1 found by Fair and Madix [39] and ν = 3 × 10 14 s −1 found by Engstrom and Weinberg [16]), a value of E d = 143 (±4) kJ/mol for the desorption activation energy for the β 1 desorption peak in the high-coverage region was obtained.…”

Section: Co Interaction With Pt{110}supporting

confidence: 93%

A Simple Angle-Resolved Thermal Molecular Beam Reactor: Applied to CO Oxidation on Pt{110}

et al. 2020

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We developed a simple form of thermal molecular beam catalytic reactor system which is capable of measuring sticking probabilities and reaction probabilities, together with angle-resolved scattering of molecules and products during catalytic reactions at the surface. This includes very fast determination of the angle dependence of the reaction product flux at steady-state. It was employed to determine the oxidation of CO on Pt{110}-(1 × 2), including individual molecular sticking and scattering. The initial sticking probability of oxygen on Pt{110} shows a small variation between 140 and 750 K surface temperature, from 0.45 to 0.28. The saturation uptake drops from 1.5 ± 0.2 ML at 140 K to 0.6 ML at 300 K and to 0.23 ± 0.02 ML at 750 K. The initial sticking probability of CO at 300 K is 0.80 and decreases to 0.62 at 470 K. Beyond that temperature, it descends steeply down to near zero at 570 K, due to the high desorption rate of CO at that temperature. Kisliuk precursor mobility parameters K were calculated from shape of the sticking curves. For 300 K, a value of 0.11 ± 0.01 was found, which increases to 0.76 ± 0.01 at 470 K, indicating a change from considerable mobility in the precursor state, to more limited mobility before desorption at high temperature. In temperature-programmed CO-O2 reaction experiments, CO2 production was observed to initiate in the temperature region 460–510 K. Using isothermal angle-resolved experiments, the CO2 flux was determined in the [11¯0] plane at temperatures of 470–620 K. Two sharp scattering lobes at positions of ±16° off the surface normal were found, with a high cosine power angle dependence, which were attributed to desorption from the {111}-like microfacets of the 1 × 2 reconstructed surface, with products evolving over a high barrier.

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Section: Co Interaction With Pt{110}supporting

confidence: 93%

A Simple Angle-Resolved Thermal Molecular Beam Reactor: Applied to CO Oxidation on Pt{110}

et al. 2020

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“…This value is in very good agreement with the 1.9 eV estimate from calorimetric experiments in the limit of low coverage (seeFigure 1in Ref 2235 and molecular beam modulation36 techniques. This discrepancy can be reconciled by noting that the CO molecule in the pre-desorption state acquires a significant entropic free-energy component from libration modes, a component that is absent in the equilibrium configuration.…”

supporting

confidence: 79%

The quantum mechanics derived atomistic mechanism underlying the acceleration of catalytic CO oxidation on Pt(110) by surface acoustic waves

Qian

Nielsen

et al. 2016

J. Mater. Chem. A

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Experimental evidence that surface acoustic waves (SAW) can significantly enhance the rate of catalytic oxidation of CO to CO 2 over the Pt(110) catalyst surface [S. Kelling et al. Faraday Disc. 1997, 107, 435−444] is examined using quantum mechanics (QM) simulations. First we determined the QM based mechanism for the O 2 -rich régime of the reaction, and the energy landscape of CO interacting with an O-covered reconstructed Pt(110) surface at both static and dynamic levels, but in the absence of SAW. We then utilized ab initio molecular dynamic (AIMD) simulations to determine how SAW might modify the kinetics. We focus here on the short (picosecond time scale) shock spikes induced by switching of domains in the piezoelectric driver on which the catalyst is deposited. We find that SAW-induced spikes promote dynamic changes in the diffusion and desorption, from which we estimate the influence of SAW on CO oxidation rate over Pt(110). We find good agreement with the experimentally observed catalytic enhancement by SAW. With an atomistic mechanism in place one can now consider how to use SAW to enhance other catalytic reactions.

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“…It is expected to increase more at lower P O 2 to the heat of CO adsorption, about 35 kcal/mol. 19 On the other hand, with increasing P O 2 , it decreased to 7 kcal/mol at P O 2 ϭ3ϫ10 Ϫ5 Torr, becoming close to the value determined from the oscillation. 2 The physical meaning of the siteswitching point became clearer than it was in our previous work, in which a rapid change of surface structures was assumed.…”

Section: Surface Phase Diagrammentioning

confidence: 91%

Surface phase transitions of Pt(110) studied by desorption dynamics of product CO2 in steady-state CO oxidation

Rzeznicka

Garza

Matsushima

2002

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The transformation of ͑1ϫ2͒ into ͑1ϫ1͒ on a Pt͑110͒ surface in the course of CO oxidation was studied through the analysis of both angular and velocity distributions of desorbing product CO 2 and low-energy electron diffraction ͑LEED͒ intensity. The intensity of half-order LEED spots decreased quickly, showing the beginning of the transformation of ͑1ϫ2͒→͑1ϫ1͒ just below the kinetic transition, where the rate-determining step switched from CO adsorption to O 2 dissociation. On the other hand, the angular distribution of desorbing CO 2 sharply changed at a CO pressure far above the kinetic transition, where ͑1ϫ2͒ domains disappeared. Below this approximate CO pressure, CO 2 was mostly formed on ͑1ϫ2͒ domains regardless of its reduced area.

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Low and high coverage determinations of the rate of carbon monoxide adsorption and desorption from Pt(110)

Cited by 91 publications

References 12 publications

A Simple Angle-Resolved Thermal Molecular Beam Reactor: Applied to CO Oxidation on Pt{110}

A Simple Angle-Resolved Thermal Molecular Beam Reactor: Applied to CO Oxidation on Pt{110}

The quantum mechanics derived atomistic mechanism underlying the acceleration of catalytic CO oxidation on Pt(110) by surface acoustic waves

Surface phase transitions of Pt(110) studied by desorption dynamics of product CO2 in steady-state CO oxidation

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