Solvation structure and dynamics for passivated Au nanoparticle in supercritical CO2: A molecular dynamic simulation

Hu, Yanyan; Wu, Bin; Xu, Zhijun; Yang, Zhen; Yang, Xiaoning

doi:10.1016/j.jcis.2010.09.051

Cited by 7 publications

(7 citation statements)

References 69 publications

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“…There is no significant difference in the energy contribution ( U direct ) between the two solvent densities, which is consistent with the previous result that the density of supercritical fluid has weak influence on the morphology of the passivating self-assembly layer. 48,64 However, our simulation results definitely show that increasing the density of scCO 2 can enhance the contribution of entropy loss term (−T S direct ), which is favorable to preclude the association of NPs. The increase in the observed entropy loss term as the solvent density increases can be understood in terms of the solvation behavior of the SAM (see Sec.…”

Section: Resultsmentioning

confidence: 69%

“…As expected, higher bulk solvent density can produce a larger confined molecule number, which is associated with the local density enhancement around the ligand segments at higher supercritical density. 15,48,64 It is clearly observed that the number of confined solvent molecules is well correlated with the corresponding solvent-induced entropy/energy term. A monotonous decrease in the confined number of solvent molecules corresponds to a gradual increase in the energy term ( U induced ) and a gradual decrease in the entropy term (−T S induced ).…”

Section: Resultsmentioning

confidence: 96%

“…At the larger separation, there is a sharp first peak at ∼4.6 Å, accompanied by an obvious valley, showing a good solvation structure of CO 2 molecules around the external CF 3 unit. 64 With the separation reducing, the first peak height decreases, demonstrating that the solvation structure is gradually declined as the surface brushes are compressed. This is consistent with the monotonous decrease of the CO 2 -induced entropy term (−T S induced ), which confirms the entropy gain in the solvent expulsion from the confined region into the bulk phase.…”

Section: Resultsmentioning

confidence: 98%

“…The interaction between Au core and CO 2 contributes very little to the overall PMF, because the penetration of CO 2 solvent to the gold surface is largely precluded from the surface passivating layer, which is in line with the previous studies. 48,64 At the density of 1ρ c , the CO 2 -SAM PMF term ( A CO 2 −SAM ) exhibits a repulsive contribution as the surface brushes approach. A more significant long-ranged repul-sive nature can be observed for the situation of longer ligand molecules (FC 12 ).…”

Section: Resultsmentioning

confidence: 99%

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Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Sun

Yang

et al. 2011

The Journal of Chemical Physics

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Molecular dynamics simulations have been performed to study the potential of mean force (PMF) between passivated gold nanoparticles (NPs) in supercritical CO(2) (scCO(2)). The nanoparticle model consists of a 140 atom gold nanocore and a surface self-assembled monolayer, in which two kinds of fluorinated alkanethiols were considered. The molecular origin of the thermodynamics interaction and the solvation effect has been comprehensively studied. The simulation results demonstrate that increasing the solvent density and ligand length can enhance the repulsive feature of the free energy between the passivated Au nanoparticles in scCO(2), which is in good agreement with previous experimental results. The interaction forces between the two passivated NPs have been decomposed to reveal various contributions to the free energy. It was revealed that the interaction between capping ligands and the interaction between the capping ligands and scCO(2) solvent molecules cooperatively determine the total PMF. A thermodynamic entropy-energy analysis for each PMF contribution was used to explain the density dependence of PMF in scCO(2) fluid. Our simulation study is expected to provide a novel microscopic understanding of the effect of scCO(2) solvent on the interaction between passivated Au nanoparticles, which is helpful to the dispersion and preparation of functional metal nanoparticles in supercritical fluids.

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Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Sun

Yang

et al. 2011

The Journal of Chemical Physics

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“…Molecular dynamics (MD) simulations have explored the local structure of nanoparticle ligands in a variety of environments, including near interfaces. − For example, Grest and co-workers demonstrated the asymmetrical ordering of alkanethiol ligands on gold cores situated in the asymmetric environment of a liquid–vapor interface. − In this work and in most subsequent MD studies, there are no free thiols in the vicinity of the ligated nanoparticles, either in the nanoparticle suspension or at the interface . However, recent work has demonstrated that exchange of thiol ligands bound to the core with free thiols in the nanoparticle suspension can alter the core-ligand coverage θ, as the two ensembles of moleculesbound and freeequilibrate .…”

mentioning

confidence: 85%

Free Thiols Regulate the Interactions and Self-Assembly of Thiol-Passivated Metal Nanoparticles

Sun

Nowack

et al. 2021

Nano Lett.

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Thiol ligands bound to the metallic core of nanoparticles determine their interactions with the environment and self-assembly. Recent studies suggest that equilibrium between bound and free thiols alters the ligand coverage of the core. Here, X-ray scattering and MD simulations investigate water-supported monolayers of gold-core nanoparticles as a function of the core-ligand coverage that is varied in experiments by adjusting the concentration of total thiols (sum of free and bound thiols). Simulations demonstrate that the presence of free thiols produces a nearly symmetrical coating of ligands on the core. X-ray measurements show that above a critical value of core-ligand coverage the nanoparticle core rises above the water surface, the edgeto-edge distance between neighboring nanoparticles increases, and the nanoparticle coverage of the surface decreases. These results demonstrate the important role of free thiols: they regulate the organization of bound thiols on the core and the interactions of nanoparticles with their surroundings.

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Synthesis of Metal Nanostructures Using Supercritical Carbon Dioxide: A Green and Upscalable Process

Siril

Türk

2020

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Metallic nanostructures have numerous applications as industrial catalysts and sensing platforms. Supercritical carbon dioxide (scCO2) is a green medium for the scalable preparation of nanomaterials. Supercritical fluid reactive deposition (SFRD) and other allied techniques can be employed for the mass production of metal nanostructures for various applications. The present article reviews the recent reports on the scCO2‐assisted preparation of zero‐valent metal nanomaterials and their applications. A brief description of the science of pure supercritical fluids, especially CO2, and the basics of binary mixtures composed of scCO2 and a low volatile substance, e.g., an organometallic precursor are presented. The benefits of using scCO2 for preparing metal nanomaterials, especially as a green solvent, are also being highlighted. The experimental conditions that are useful for the tuning of particle properties are reviewed thoroughly. The range of modifications to the classical SFRD methods and the variety of metallic nanomaterials that can be synthesized are reviewed and presented. Finally, the broad ranges of applications that are reported for the metallic nanomaterials that are synthesized using scCO2 are reviewed. A brief summary along with perspectives about future research directions is also presented.

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Solvation structure and dynamics for passivated Au nanoparticle in supercritical CO2: A molecular dynamic simulation

Cited by 7 publications

References 69 publications

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Free Thiols Regulate the Interactions and Self-Assembly of Thiol-Passivated Metal Nanoparticles

Synthesis of Metal Nanostructures Using Supercritical Carbon Dioxide: A Green and Upscalable Process

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