Monolayer bimetallic surfaces: Experimental and theoretical studies of trends in electronic and chemical properties

Chen, Jingguang G.; Menning, Carl A.; Zellner, Michael B.

doi:10.1016/j.surfrep.2008.02.001

Cited by 483 publications

(425 citation statements)

References 559 publications

(462 reference statements)

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“…Bimetallic particles of same size, shape, and composition show significant differences in activity when configured into different architectures such as alloy, cluster in cluster, core-shell or monometallic mixtures. The structure of bimetallic combination depends on the preparation conditions, miscibility and the kinetics of the reduction of metal ions on the surface of the catalyst [206][207][208][209][210]. Au/Pt-TiO 2 obtained by the hydrolysis of titanium isopropoxide in microemulsion system followed by reduction of HAuCl 4 (precursor for gold) and K 2 PtCl 4 (precursor for palladium) along with NaBH 4 for the bimetallic deposition and the catalyst was further calcined at 450 • C. This catalyst exhibited high rates for phenol degradation under visible light irradiation [210].…”

Section: Photocatalytic Activity Of Titania With Bimetallic Surface Dmentioning

confidence: 99%

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

Devi

Kavitha

2016

Applied Surface Science

309

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Section: Photocatalytic Activity Of Titania With Bimetallic Surface Dmentioning

confidence: 99%

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

Devi

Kavitha

2016

Applied Surface Science

309

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“…12 We also studied O 2 dissociation on Pt(111) and a Pt-skin layer on Pt 3 Ni, and a similar trend (0.71 eV on Pt(111) vs 0.97 eV on the Pt-skin) was found. 51,74 On the other hand, adsorption of CO, H, O, and O 2 on Pt-skin surfaces is weakened by the subsurface TMs, 9,10,32,[51][52][53]60 but the destabilization occurs with a similar magnitude. 44,51 For example, binding energies of CO and O 2 on a Pt-skin with subsurface Ru are -1.25 and -0.26 eV, respectively, compared to -1.82 eV/CO and -0.65 eV/O 2 on Pt(111).…”

Section: ' Introductionmentioning

confidence: 99%

“…77 On the other hand, inward diffusion of surface 3d-TMs into the subsurface or even bulk regions of Pt crystals may happen upon heating in UHV or reductive atmospheres ( Figure S2). 10,56,60,62,78,79 Accordingly, the surface structure of the PtNi/CB catalysts can be simply controlled by reduction in H 2 . For this purpose, our PtNi/CB catalysts were reduced in H 2 for 2 h at 423, 523, and 623 K, respectively.…”

Section: ' Introductionmentioning

confidence: 99%

Synergetic Effect of Surface and Subsurface Ni Species at Pt−Ni Bimetallic Catalysts for CO Oxidation

et al. 2011

J. Am. Chem. Soc.

265

193

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Various well-defined Ni-Pt(111) model catalysts are constructed at atomiclevel precision under ultra-high-vacuum conditions and characterized by X-ray photoelectron spectroscopy and scanning tunneling microscopy. Subsequent studies of CO oxidation over the surfaces show that a sandwich surface (NiO 1-x /Pt/Ni/Pt(111)) consisting of both surface Ni oxide nanoislands and subsurface Ni atoms at a Pt(111) surface presents the highest reactivity. A similar sandwich structure has been obtained in supported Pt-Ni nanoparticles via activation in H 2 at an intermediate temperature and established by techniques including acid leaching, inductively coupled plasma, and X-ray adsorption nearedge structure. Among the supported Pt-Ni catalysts studied, the sandwich bimetallic catalysts demonstrate the highest activity to CO oxidation, where 100% CO conversion occurs near room temperature. Both surface science studies of model catalysts and catalytic reaction experiments on supported catalysts illustrate the synergetic effect of the surface and subsurface Ni species on the CO oxidation, in which the surface Ni oxide nanoislands activate O 2 , producing atomic O species, while the subsurface Ni atoms further enhance the elementary reaction of CO oxidation with O.

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“…These studies indicated that novel phenomena may be observed for such ultrathin overlayers, but specialized techniques are required to fabricate these surfaces. A review paper by Chen et al [6] summarizes the body of ultra-high-vacuum and density functional work on this type of overlayersupport system. In contrast to these works, this study uses an electrochemical technique called surface limited redox replacement (SLRR) to create Pt-Au adlayer-substrate samples to study these properties.…”

Section: Introductionmentioning

confidence: 99%

Near Surface Phase Transition of Solute Derived Pt Monolayers

et al. 2013

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As the loadings of precious metals in surfacechemical systems continue to decrease for photo-and electro-catalysts for energy and environmental applications, the study of near-surface electronic and atomic structure in functional materials becomes critically important. Extremely small quantities of active elements, whether grown as clusters or ultrathin films, exhibit changes in catalytic activity that arise from both size effects and electron-transfer effects. These size and transfer effects can be related to increased propensity for oxidation of the metallic deposit, as well as to various changes in electrochemical performance such as durability or required overpotential for a given reaction. This work establishes a minimum threshold for Pt loading beyond which bulk-type electronic behavior may be expected. By iteratively growing atomic monolayers and multilayers using selflimited electrodeposition and studying these films using core-electron spectroscopy (X-ray absorption and X-ray photoelectron spectroscopy), electrochemical methods and DFT-based computations the fundamental interactions that govern oxidation state and electron transfer near the surface of a Pt-Au bimetallic system have been explored. It has been shown that the Pt-Au system exhibits increased tendency for the Pt layer to remain cationic below a minimum threshold film thickness of two monolayers. At monodispersed levels of submonolayer coverage Pt exhibits deviated electronic structure, reactivity, and metal stability compared to films in excess of this minimum threshold thickness. At three monolayers Pt is thick enough to avoid the preference for cationicity and the resulting higher rates of metal dissolution, but thin enough to benefit from electron transfers from Au that assist in lowering the overpotentials for CO oxidation. This study shows the efficacy of a concerted method for the investigation of near-surface phenomena in multicomponent systems. By combining electrochemical and vacuum studies of solutederived samples with advanced computational techniques, a multifaceted understanding of these architectures has been achieved.

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Monolayer bimetallic surfaces: Experimental and theoretical studies of trends in electronic and chemical properties

Cited by 483 publications

References 559 publications

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

Synergetic Effect of Surface and Subsurface Ni Species at Pt−Ni Bimetallic Catalysts for CO Oxidation

Near Surface Phase Transition of Solute Derived Pt Monolayers

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