Oxidation of Pt(100)-hex-R0.7° by gas-phase oxygen atoms

Shumbera, R. Bradley; Kan, Heywood H.; Weaver, Jason F.

doi:10.1016/j.susc.2006.09.040

Cited by 40 publications

(27 citation statements)

References 40 publications

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“…Recent studies suggest that under conditions of high oxygen pressure, the metallic transition metal is covered by ultrathin oxide overlayers or convert to the metal oxide, which tends to have positive effects on the reaction rate and the ethylene oxide selectivity. According to the previous works applying the first-principles-aided thermodynamic modeling to investigate the phase diagram of the transition metal in oxygen conditions (Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh Ru), we select the corresponding stable surface phase of the transition metal in the reaction environment of ethylene epoxidation as the model surface (see details in Computational Methods and Figures a,c,e and S1). Au and Pt keep their metallic state in the reaction environment of ethylene epoxidation.…”

Section: Resultsmentioning

confidence: 99%

Revisit the Role of Metal Dopants in Enhancing the Selectivity of Ag-Catalyzed Ethylene Epoxidation: Optimizing Oxophilicity of Reaction Site via Cocatalytic Mechanism

Zhu

Yang

et al. 2021

ACS Catal.

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The pristine transition metals (TMs) offer limited choices for high-performance heterogeneous catalysts because they are usually restricted in less optimal regions on the reactivity volcano map. Using ethylene epoxidation as a probe reaction, it is found that the reaction pathway selection is determined by the binding affinity of catalytic sites toward oxygen and carbon. By introducing extrinsic metal dopants to engineer the oxygen affinity of reactive sites of host Ag catalyst, the optimal (peak) region on the selectivity volcano map can be reached after optimizing the adsorption energies of atomic oxygen. The oxidation formation enthalpy (ΔH metal‑oxide) is employed as a descriptor to screen metal dopants, and the promising metal elements are identified as either single or dual dopants to achieve higher catalytic selectivity than pristine Ag catalysts, validated by the available experimental data. Our investigation demonstrated that, in addition to the traditional promoter mechanism, metal dopants also realize catalytic selectivity improvement of Ag-catalyzed ethylene epoxidation through a cocatalytic mechanism. By acting as cocatalytic sites to participate in the reaction, metal dopants modify the element affinity of the reaction center, such as oxophilicity, and disproportionally alter the adsorption strength of the key intermediates to enhance the reactivity of pristine TM catalysts, which may be applied in heterogeneous reactions beyond ethylene epoxidation.

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Section: Resultsmentioning

confidence: 99%

Revisit the Role of Metal Dopants in Enhancing the Selectivity of Ag-Catalyzed Ethylene Epoxidation: Optimizing Oxophilicity of Reaction Site via Cocatalytic Mechanism

Zhu

Yang

et al. 2021

ACS Catal.

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“…For the O/Pt(111) system, experiments have reported that the thermal stability of a surface Pt oxide on Pt single crystal surfaces significantly exceeds that of bulk PtO 2 [57], and furthermore that structurally similar oxides develop on both Pt (111) and Pt (100). While there have been a number of recent first-principles investigations into the stability of surface oxides at Pt (110) and Pt(100), much fewer have been reported on Pt (111).…”

Section: The Oxygen-palladium (111) Systemmentioning

confidence: 99%

Bridging the temperature and pressure gaps: close-packed transition metal surfaces in an oxygen environment

Stampfl

Soon

Piccinin

et al. 2008

J. Phys.: Condens. Matter

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An understanding of the interaction of atoms and molecules with solid surfaces on the microscopic level is of crucial importance to many, if not most, modern high-tech materials applications. Obtaining such accurate, quantitative information has traditionally been the realm of surface science experiments, carried out under ultra-high vacuum conditions. Over recent years scientists have realized the importance of obtaining such knowledge also under the high pressure and temperature conditions under which many industrial processes take place, e.g. heterogeneous catalysis, since the material under these conditions may be quite different to that under the conditions of typical surface science experiments. Theoretical studies too have been aimed at bridging the so-called pressure and temperature gaps, and great strides have been made in recent years, often in conjunction with experiment. Here we review recent progress in the understanding of the hexagonal close-packed surfaces of late transition and noble metals in an oxygen environment, which is of relevance to many heterogeneous catalytic reactions. In many cases it is found that, on exposure to high oxygen pressures and elevated temperatures, thin oxide-like structures form which may or may not be stable, and which may have little similarity to the bulk oxides, and thus possess unique chemical and physical properties.

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“…Phase transformations [1], formations of nanostructures [1,2], metastable phases [3] or agglomerations [4], as well as chemical reactions [5] are all phenomena which become special at surfaces. A surface can also pose a major barrier to transport [6,7].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic characterization of two layers of CO2 on a graphite surface

Trinh

Bedeaux

Simon

et al. 2014

Chemical Physics Letters

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a b s t r a c tWe find by examination of density profiles that carbon dioxide adsorbs on graphite in two distinct layers. We report the activity coefficient, entropy and enthalpy for CO 2 in each layer using a convenient computational method, the Small System Method, thereby extending this method to surfaces. This opens up the possibility to study thermodynamic properties for a wide range of surface phenomena.

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Oxidation of Pt(100)-hex-R0.7° by gas-phase oxygen atoms

Cited by 40 publications

References 40 publications

Revisit the Role of Metal Dopants in Enhancing the Selectivity of Ag-Catalyzed Ethylene Epoxidation: Optimizing Oxophilicity of Reaction Site via Cocatalytic Mechanism

Revisit the Role of Metal Dopants in Enhancing the Selectivity of Ag-Catalyzed Ethylene Epoxidation: Optimizing Oxophilicity of Reaction Site via Cocatalytic Mechanism

Bridging the temperature and pressure gaps: close-packed transition metal surfaces in an oxygen environment

Thermodynamic characterization of two layers of CO2 on a graphite surface

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