Self-assembled monolayers of thiolates on metals: a review article on sulfur-metal chemistry and surface structures

Vericat, Carolina; Vela, M. E.; Corthey, Gastón; Pensa, Evangelina; Cortés, Emiliano; Fonticelli, Mariano H.; Ibáñez, Francisco Javier Muñoz; Benítez, G.; Carro, Pilar; Salvarezza, Roberto Carlos

doi:10.1039/c4ra04659e

Cited by 193 publications

(235 citation statements)

References 212 publications

(389 reference statements)

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“…We use first-principles calculations to compute the energy barrier for diffusion of gold atoms and Au-alkanethiolate species over a range of surface structures, providing estimated thermodynamic penalties for the different stages of dissociation, from low-barrier migration, or rolling, through to complete unbinding. Our data and analysis complements recent STM studies of molecule-induced rearrangements and adatom migration on gold, 14,[28][29][30][31][32][33] which investigate the effect of surface features including grain boundaries and pores. 20,34 We calculate a barrier of 3 eV for complete gold atom unbinding, consistent with the upper bound of literature values that range from approx.…”

Section: Introductionsupporting

confidence: 86%

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

et al. 2015

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Activation energies E a measured from molecular exchange experiments are combined with atomic-scale calculations to describe the migration of bare Au atoms and Au-alkanethiolate species on gold nanoparticle surfaces during ligand exchange for the creation of metal-molecule-metal junctions. It is well known that Au atoms and alkanethiol-Au species can diffuse on gold with sub-1 eV barriers, and surface restructuring is crucial for self-assembled monolayer (SAM) formation, for interlinking nanoparticles and in contacting nanoparticles to electrodes. In the present work, computer simulations reveal that naturally occurring ridges and adlayers on Au(111) are etched and resculpted by migration of alkanethiolate-Au species towards high coordination kink sites at surface step edges. The calculated energy barrier E b for diffusion via step edges is 0.4-0.7 eV, close to the experimentally-measured E a of 0.5-0.7 eV. By contrast, putative migration from isolated nine-coordinated terrace sites and complete Au unbinding from the surface incur significantly larger barriers of +1 and +3 eV, respectively. Molecular van der Waals's packing energies are calculated to have negligible effect on migration barriers for typically-used molecules (length < 2.5nm), indicating that migration inside SAMs does not change the size of the migration barrier. We use the computational methodology to propose a means of creating Au nanoparticle arrays via selective replacement of citrate protector molecules by thiocyanate linker molecules on surface step sites. This work also outlines the possibility of using Au/Pt alloys as possible candidates for creation of contacts that are well-formed and long-lived, due to the superior stability of Pt interfaces against atomic migration.

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Section: Introductionsupporting

confidence: 86%

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

et al. 2015

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“…27,28 The presence of partial PdS x layer on the surface of PdNP after thiolate monolayer formation, which has been observed by others, might also be the reason for deactivation of PdNP catalyst. 36 …”

Section: Resultsmentioning

confidence: 99%

Mechanistic interpretation of selective catalytic hydrogenation and isomerization of alkenes and dienes by ligand deactivated Pd nanoparticles

Zhu

Shon

2015

Nanoscale

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Unsupported thiolate-capped palladium nanoparticle catalysts are found to be highly substrate-selective for alkene hydrogenation and isomerization. Steric and poisoning effects from thiolate ligands on the nanoparticle surface control reactivity and selectivity by influencing alkene adsorption and directing either di-σ or mono-σ bond formation. The presence of overlapping p orbitals and α protons in alkenes greatly influences the catalytic properties of deactivated palladium nanoparticles leading to easily predictable hydrogenation or isomerization products.

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“…The dramatic decrease in methanol oxidation performance for PtNCs with ligands possibly originates from the formation of a PdS interlayer which blocks catalytic sites of PtNCs. 10 The surface ligands block catalytic sites and decrease electrocatalytic activity dramatically. Moreover, the size effect of AuNCs was also examined using ligand-free 6 nm AuNC-PGCs.…”

mentioning

confidence: 99%

Ligand-Free Noble Metal Nanocluster Catalysts on Carbon Supports via “Soft” Nitriding

Liu¹,

Yao

Song³

et al. 2016

J. Am. Chem. Soc.

203

166

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We report a robust, universal “soft” nitriding method to grow in situ ligand-free ultrasmall noble metal nanocatalysts (UNMN; e.g., Au, Pd, and Pt) onto carbon. Using low-temperature urea pretreatment at 300 °C, soft nitriding enriches nitrogen-containing species on the surface of carbon supports and enhances the affinity of noble metal precursors onto these supports. We demonstrated sub-2-nm, ligand-free UNMNs grown in situ on seven different types of nitrided carbons with no organic ligands via chemical reduction or thermolysis. Ligand-free UNMNs supported on carbon showed superior electrocatalytic activity for methanol oxidation compared to counterparts with surface capping agents or larger nanocrystals on the same carbon supports. Our method is expected to provide guidelines for the preparation of ligand-free UNMNs on a variety of supports and, additionally, to broaden their applications in energy conversion and electrochemical catalysis.

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Self-assembled monolayers of thiolates on metals: a review article on sulfur-metal chemistry and surface structures

Abstract: A review article on fundamental aspects of thiolate self-assembled monolayers (SAMs) on the (111) and (100) surfaces of the Cu and Ni groups is presented.

Cited by 193 publications

References 212 publications

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

Mechanistic interpretation of selective catalytic hydrogenation and isomerization of alkenes and dienes by ligand deactivated Pd nanoparticles

Ligand-Free Noble Metal Nanocluster Catalysts on Carbon Supports via “Soft” Nitriding

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