Size Selected Clusters on Surfaces

Tang, Xin; Li, X; Wang, Y; Wepasnick, Kevin A.; Lim, Alane; Fairbrother, D. Howard; Bowen, Kit H.; Mangler, T.; Noessner, S.; Wolke, Conrad T.; Großmann, Martin; Koop, Alexander; Gantefoer, Gerd; Kiran, Boggavarapu; Kandalam, Anil K.

doi:10.1088/1742-6596/438/1/012005

Cited by 10 publications

(11 citation statements)

References 31 publications

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“…The sample can be transferred between two vertical manipulators by a horizontal magnetic transfer arm. More details about this apparatus are described elsewhere …”

Section: Experimental Sectionmentioning

confidence: 99%

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

et al. 2021

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Room temperature decomposition and thermal decomposition of dimethyl methylphosphonate (DMMP), a chemical warfare agent (CWA) simulant, on size-selected copper clusters have been studied via combined X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD). Cu100 and (CuO)80, which have the same nominal masses, were chosen to present a direct comparison between the reactivity of metallic copper and that of cupric oxide with DMMP. Room temperature XPS results have shown that most of the DMMP molecules decompose completely and reductively into atomic phosphorus on Cu100, while almost all the DMMP molecules are only dissociatively adsorbed on (CuO)80 as methyl methylphosphonate (MMP). XPS and TPD have been carried out to analyze the thermal decomposition of adsorbed DMMP by identifying the surface species after annealing to certain temperatures and the gaseous products evolved during linear temperature ramps, respectively. Methanol, formaldehyde, and methane are the three most significant gaseous products for DMMP decomposition on both Cu100 and (CuO)80. Methanol and formaldehyde, which evolve in the low temperature region, are believed to originate from surface methoxy species. Methanol, formaldehyde, and methane evolved in the high temperature region are related to further decomposition of the phosphorus-containing surface species. A set of methanol-probed TPD experiments have also been carried out, which suggest that methane evolution originates from the methyl group within DMMP instead of the surface methoxy species.

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“…The sample can be transferred between two vertical manipulators by a horizontal magnetic transfer arm. More details about this apparatus are described elsewhere …”

Section: Experimental Sectionmentioning

confidence: 99%

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

et al. 2021

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“…Metal nanoparticles can be prepared in the gas phase before their subsequent transfer on substrates [65][66][67][68]. Such particles can be quite large, and sustain a much more significant binding to the substrate than single adatoms.…”

Section: Interaction Of Larger Adsorbatesmentioning

confidence: 99%

Adsorption of metal nanoparticles on carbon substrates and epitaxial graphene: Assessing models for dispersion forces

2015

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Carbon substrates such as graphite or epitaxial graphene can be employed to support metal nanoparticles for applications in diverse areas of surface science. In this paper, we address the computational modeling of such systems by means of semiempirical potentials, and in particular the possible role of long-range London dispersion forces. Following the Grimme (D2) strategy often used in combination with density-functional theory calculations, we propose some analytical extensions taking into account the crystalline and semi-infinite natures of the substrate and, in the case of epitaxial graphene, the possible screening of the van der Waals interaction by the bulk underlying metal. These ideas are tested in the specific case of platinum nanoparticles deposited on graphene, graphite, and graphene epitaxially grown on Pt(111) modeled using a many-body Brenner-type potential, and validated against available electronic-structure calculations. Systematic optimizations carried out at zero temperature indicate the relative stability of various nanoparticle shapes on their support, for adsorbates containing several thousand atoms. Using molecular dynamics simulations, we shed light on the thermal behavior and emphasize the key role of dispersion forces on the stabilization of the adsorbates at finite temperature. The vibrational properties of graphene layers in contact with a Pt nanoparticle or epitaxially grown on Pt(111) also reveal some clear sensitivity on temperature and strain.

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“…Atomic/molecular level mechanisms for condensed phase catalytic reactions are suggested to be accurately modeled and understood through the study of gas phase cluster reactions. [16][17][18][19] Titanium oxide clusters have thereby been the subject of intense investigation in recent years, and evolving cluster models have been frequently employed in theoretical calculations of titanium dioxide bulk or surface properties, [20][21][22] even though the physical and chemical properties of TiO 2 nanomaterials, namely nanowires, nanoparticles and clusters, might be different from those of bulk titania. 23 In general, the ratio of surface to volume atoms increases as the cluster size decreases; accordingly, smaller TiO 2 nanoparticles have more active sites, with respect to photo-catalytic applications, because of the high density of surface corner, step, and edge atoms.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical studies of H₂O oxidation by neutral Ti₂O_4,5 clusters under visible light irradiation

Yin

Bernstein

2014

Phys. Chem. Chem. Phys.

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A new photo excitation fast flow reactor system is constructed and used to investigate reactions of neutral TimOn clusters with H2O under visible (532 nm) light irradiation. Single photon ionization at 118 nm (10.5 eV) is used to detect neutral cluster distributions through time of flight mass spectrometry. TimOn clusters are generated through laser ablation of a titanium target in the presence of 4% O2/He carrier gas. Association products Ti2O4(H2O) and Ti2O5(H2O) are observed for reactions of H2O and TimOn clusters without irradiation. Under 532 nm visible light irradiation of the fast flow reactor, only the Ti2O5(H2O) feature disappears. This light activated reaction suggests that visible radiation can induce chemistry for Ti2O5(H2O), but not for Ti2O4(H2O). Density functional theory (DFT) and time-dependent (TD) DFT calculations are performed to explore the ground and first excited state potential energy surfaces (PES) for the reaction Ti2O5 + H2O → Ti2O4 + H2O2. A high barrier (1.33 eV) and a thermodynamically unfavorable (1.14 eV) pathway are obtained on the ground state PES for the Ti2O5 + H2O reaction; the reaction is also thermodynamically unfavorable (1.54 eV) on the first singlet excited state PES. The reaction is proposed to occur on the ground state PES through a conical intersection ((S1/S0)CI), and to generate products Ti2O4 and H2O2 on the ground state PES. This mechanism is substantiated by a multi-reference ab initio calculation at the complete active space self-consistent field (CASSCF) level. The S0-S1 vertical excitation energy of Ti2O4 (3.66 eV) is much higher than the 532 nm photon energy (2.33 eV), suggesting this visible light driven reaction is unfavorable for the Ti2O4 cluster. The TDDFT calculated optical absorption spectra of Ti2O4 and Ti2O5 further indicate that Ti2O5 like structures on a titanium oxide surface are the active catalytic sites for visible light photo-catalytic oxidation of water.

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Size Selected Clusters on Surfaces

Abstract: The impact of size-selected Ag clusters on graphite: anSTM study S J Carroll, P Weibel, B von Issendorff et al. - Recent citations

Cited by 10 publications

References 31 publications

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

Adsorption of metal nanoparticles on carbon substrates and epitaxial graphene: Assessing models for dispersion forces

Experimental and theoretical studies of H₂O oxidation by neutral Ti₂O_4,5 clusters under visible light irradiation

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Size Selected Clusters on Surfaces

Abstract: The impact of size-selected Ag clusters on graphite: anSTM study S J Carroll, P Weibel, B von Issendorff et al. - Recent citations

Cited by 10 publications

References 31 publications

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

Thermal Decomposition of Dimethyl Methylphosphonate on Size-Selected Clusters: A Comparative Study between Copper Metal and Cupric Oxide Clusters

Adsorption of metal nanoparticles on carbon substrates and epitaxial graphene: Assessing models for dispersion forces

Experimental and theoretical studies of H2O oxidation by neutral Ti2O4,5 clusters under visible light irradiation

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Product

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Experimental and theoretical studies of H₂O oxidation by neutral Ti₂O_4,5 clusters under visible light irradiation