How does tuning the van der Waals bonding strength affect adsorbate structure?

Maier, Philipp; Xavier, Neubi Francisco; Truscott, Christopher; Hansen, Thomas C.; Fouquet, Peter; Sacchi, Marco; Tamtögl, Anton

doi:10.1039/d2cp03468a

Cited by 3 publications

(3 citation statements)

References 64 publications

(156 reference statements)

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“…Given the chemical similarity between PPh 3 and previously reported organic precursors, we expect that the accuracy of our calculations with PBE and TS corrections (see Computational details) will be comparable with our previous studies on graphitic and similar surfaces 4 , 5 , 20 , 21 , on the order of 10 meV. Table 1 shows the adsorption energies E a for two different rotations in the downward configuration at the different adsorption sites (for the complete set of DFT calculations including all considered adsorption geometries please refer to the Supplementary DFT calculations and Supplementary Table 1) .…”

Section: Resultssupporting

confidence: 77%

“…The samples were then heated in a furnace to 400 °C to sublimate the PPh 3 and promote its adsorption in the whole volume of the sample, in analogy to Refs. 4 , 5 .…”

Section: Methodsmentioning

confidence: 99%

“…While the diffusion of polycyclic aromatic hydrocarbons (PAH) on graphite has been subject to several recent studies 4 – 7 , the dynamics of other species on graphite is relatively unexplored. In general, surface diffusion in true thermal equilibrium has been mostly concerned with either very small molecules or flat adsorption geometries, as in the case of PAHs.…”

Section: Introductionmentioning

confidence: 99%

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Molecular motion of a nanoscopic moonlander via translations and rotations of triphenylphosphine on graphite

Tamtögl,

Sacchi,

Schwab

et al. 2024

Commun Chem

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Mass transport at surfaces determines the kinetics of processes such as heterogeneous catalysis and thin-film growth, with the diffusivity being controlled by excitation across a translational barrier. Here, we use neutron spectroscopy to follow the nanoscopic motion of triphenylphosphine (P(C6H5)3 or PPh3) adsorbed on exfoliated graphite. Together with force-field molecular dynamics simulations, we show that the motion is similar to that of a molecular motor, i.e. PPh3 rolls over the surface with an almost negligible activation energy for rotations and motion of the phenyl groups and a comparably small activation energy for translation. While rotations and intramolecular motion dominate up to about 300 K, the molecules follow an additional translational jump-motion across the surface from 350-500 K. The unique behaviour of PPh3 is due to its three-point binding with the surface: Along with van der Waals corrected density functional theory calculations, we illustrate that the adsorption energy of PPh3 increases considerably compared to molecules with flat adsorption geometry, yet the effective diffusion barrier for translational motion increases only slightly. We rationalise these results in terms of molecular symmetry, structure and contact angle, illustrating that the molecular degrees of freedom in larger molecules are intimately connected with the diffusivity.

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Section: Resultssupporting

confidence: 77%

“…The samples were then heated in a furnace to 400 °C to sublimate the PPh 3 and promote its adsorption in the whole volume of the sample, in analogy to Refs. 4 , 5 .…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular motion of a nanoscopic moonlander via translations and rotations of triphenylphosphine on graphite

Tamtögl,

Sacchi,

Schwab

et al. 2024

Commun Chem

Self Cite

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Anisotropic Redox on Pristine Graphene

Saraf,

Lim,

Saraf

2024

Adv Materials Inter

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Chemically modified graphene is an attractive electrode material for electrocatalysis, energy devices, and sensors, whereas pristine graphene is electrochemically passive. The remarkable anisotropic electrochemical nature of graphene is uncovered by π–π interaction, making pristine graphene more active than bare Au. The π–π stacking during redox reaction “dopes” the graphene, disrupting the passivating hydration layer, making it a facile electrochemical electrode. The structure during π–π stacking‐mediated redox of methylene blue (MB) is quantitatively measured by the differential reflectivity of a polarized laser on a ≈100 micron spot. The local redox reaction current varies over fourfold due to the orientation of the ≈10 micron size grains. The mosaic‐grain anisotropy on each spot shows local uniaxial orientation. The redox signal at the optimum orientation is over 2.5‐fold greater than that for bare Au on the same electrode. The redox signal is over fivefold greater at the edges of graphene compared bare Au. Remarkably, the π–π interaction increases chemical stability significantly, leading to negligible photo‐degradation at the approximate absorption wavelength of MB. The exclusive redox activity due to π–π interaction on pristine graphene adds to the toolbox of making exotic opto‐electrochemical electrode materials for electrocatalysis, sensing, and electronics.

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Avant-Garde Polymer and Nano-Graphite-Derived Nanocomposites—Versatility and Implications

Kausar

2023

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Graphite (stacked graphene layers) has been modified in several ways to enhance its potential properties/utilities. One approach is to convert graphite into a unique ‘nano-graphite’ form. Nano-graphite consists of few-layered graphene, multi-layered graphene, graphite nanoplatelets, and other graphene aggregates. Graphite can be converted to nano-graphite using physical and chemical methods. Nano-graphite, similar to graphite, has been reinforced in conducting polymers/thermoplastics/rubbery matrices to develop high-performance nanocomposites. Nano-graphite and polymer/nano-graphite nanomaterials have characteristics that are advantageous over those of pristine graphitic materials. This review basically highlights the essential features, design versatilities, and applications of polymer/nano-graphite nanocomposites in solar cells, electromagnetic shielding, and electronic devices.

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How does tuning the van der Waals bonding strength affect adsorbate structure?

Abstract: Organic molecular thin-films are employed for manufacturing a wide variety of electronic devices, including memories and transistors. A precise description of the atomic-scale interactions in aromatic carbon systems is of...

Cited by 3 publications

References 64 publications

Molecular motion of a nanoscopic moonlander via translations and rotations of triphenylphosphine on graphite

Molecular motion of a nanoscopic moonlander via translations and rotations of triphenylphosphine on graphite

Anisotropic Redox on Pristine Graphene

Avant-Garde Polymer and Nano-Graphite-Derived Nanocomposites—Versatility and Implications

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