Role of solvent in metal-on-metal surface diffusion: A case for rational solvent selection for materials synthesis

Imandi, Venkataramana; Jagannath, Mantha Sai Pavan; Chatterjee, Abhijit

doi:10.1016/j.susc.2018.04.016

Cited by 9 publications

(4 citation statements)

References 35 publications

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“…However, employing these computationally expensive electronic structure calculations makes the problem intractable. As a result, a standard approximation used in the modeling of metal–solvent (M–S) systems involves representing a solvent molecule by a single coarse-grained particle. , Solvent–solvent (S–S) particles separated by distance r ij interact via the Lennard-Jones (LJ) potential Here, we choose σ S–S = 2.95 Å and ϵ S–S / k B = 61.6 K (0.5 kJ/mol). LJ potentials were developed for M–S systems, wherein both metal–metal (M–M) and M–S interactions are described by the LJ form .…”

Section: Computational Methodologymentioning

confidence: 99%

“…As a result, a standard approximation used in the modeling of metal−solvent (M−S) systems involves representing a solvent molecule by a single coarse-grained particle. 55,56 Solvent−solvent (S−S) particles separated by distance r ij interact via the Lennard-Jones (LJ) potential i k j j j j j j j j i k j j j j j j y { z z z z z z i k j j j j j j y…”

Section: Computational Methodologymentioning

confidence: 99%

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Kinetic Map for Destabilization of Pt-Skin Au Nanoparticles via Atomic Scale Rearrangements

2018

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A commonly used strategy to enhance the mass activity of Pt-based catalysts involves the synthesis of Au nanoparticles (NPs) with a monolayer-thick Pt-skin layer. The synergistic effect of Au and Pt results in a higher catalytic activity and better Pt utilization. However, the stability of the Pt-skin layer is questionable as our recent equilibrium Monte Carlo simulations predict that eventually the surface Pt is replaced by Au. The role of Au during destabilization of Pt-skin in vacuum and solution is investigated with the help of molecular dynamics. Different starting Au–Pt arrangements are studied mimicking various NP synthesis approaches. Beyond a critical number of atoms in a Pt cluster, the ideal Pt monolayer rapidly transforms to a three-dimensional (3D) Pt cluster. This is supported by our model predicting transition from the Pt monolayer to Volmer–Weber growth in the Au–Pt system. At room temperature, Pt atoms move into the subsurface layer at second timescales mainly via the exchange mechanism involving Au atoms or Au climbing on top of Pt. For all practical purposes, the experimental “Pt-skin” Au NPs may actually correspond to a single layer of surface Au over subsurface Pt layers. Presence of large 3D Pt clusters may slowdown the climbing of Au atoms on Pt, thereby delaying the formation of Au-skin.

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Section: Computational Methodologymentioning

confidence: 99%

Section: Computational Methodologymentioning

confidence: 99%

Kinetic Map for Destabilization of Pt-Skin Au Nanoparticles via Atomic Scale Rearrangements

2018

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“…The LJ potential well depth ϵ S–S (0.00531 eV) yields a reasonably correct water density and radial distribution function at room temperature. , The metal–solvent (M–S) interactions are also modeled using the LJ potential. Here, the LJ potential well depth ϵ M–S (0.00531 eV) is chosen such that the surface energy of the metal–solvent interface is correctly obtained (see Section S1 of the Supporting Information). Use of LJ potentials for M–S and S–S interactions is not new .…”

Section: Computational Methodologymentioning

confidence: 99%

How the Facet Edge Controls the Overall CO Oxidation in Nanoporous Gold: Combined Atomistic Characterization/DFT Study of Residual Ag Distribution and Catalytic Activity

Sandupatla

Rana

et al. 2022

ACS Catal.

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Nanoporous gold (NPG) formed via dealloying/selective dissolution of the Au−Ag alloy is known to be catalytically active toward CO oxidation reaction (COR) even at room temperature. The atomistically resolved NPG structure is obtained by simulating the dealloying of Au 25 Ag 75 nanoparticles using a combination of kinetic Monte Carlo and molecular dynamics. The effect of adsorbed O is included. The experiment-like NPG structures from these computer simulations are characterized. We map the surface of NPG, determine the diverse binding sites, and assess their role in catalyzing the COR. Local surface Ag composition, population density of undercoordinated Au/Ag atoms, and cluster size distribution of surface Ag atoms are measured. A high density of dislocation defects is found in the simulated structure. The rate-determining steps, namely, O 2 binding and dissociation, are probed using density functional theory. We conclude that O 2 binding/dissociation is facilitated at the facet edge. Residual Ag at the edge aids in the capture of O 2 . Subsequently, O 2 dissociates after spilling over to Au sites at the facet edge. These conclusions are confirmed by showing that the normalized facet edge length of NPG and supported Au nanoparticles is linearly correlated to the experimental turnover frequency.

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“…Here 𝑝𝑎𝑖𝑟 = 𝑀 − 𝑂, 𝑀 − 𝑆, 𝑂 − 𝑂, 𝑆 − 𝑆 and 𝑂 − 𝑆, where 𝑀 = 𝐴𝑢, 𝐴𝑔. The 𝑆 − 𝑆 and 𝑀 − 𝑆 parameters are available from (Imandi et al, 2018). This leaves 8 parameters to be determined.…”

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confidence: 99%

How the Facet Edge Controls the Overall CO Oxidation in Nanoporous Gold: Combined Atomistic Characterization/DFT Study of Residual Ag Distribution and Catalytic Activity

Ayadathil,

Sandupatla,

Chatterjee

2023

Meet. Abstr.

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Nanoporous gold (NPG) formed via dealloying/selective dissolution of the Au−Ag alloy is known to be catalytically active toward CO oxidation reaction (COR) even at room temperature. The atomistically resolved NPG structure is obtained by simulating the dealloying of Au25Ag75 nanoparticles using a combination of kinetic Monte Carlo and molecular dynamics. The effect of adsorbed O is included. The experiment-like NPG structures from these computer simulations are characterized. We map the surface of NPG, determine the diverse binding sites, and assess their role in catalysing the COR. Local surface Ag composition, population density of undercoordinated Au/Ag atoms, and cluster size distribution of surface Ag atoms are measured. A high density of dislocation defects is found in the simulated structure. The rate-determining steps, namely, O2 binding and dissociation, are probed using density functional theory. We conclude that O2 binding/dissociation is facilitated at the facet edge. Residual Ag at the edge aids in the capture of O2. Subsequently, O2 dissociates after spilling over to Au sites at the facet edge. These conclusions are confirmed by showing that the normalized facet edge length of NPG and supported Au nanoparticles is linearly correlated to the experimental turnover frequency. Keywords: nanoporous gold, dealloying, CO oxidation, elemental distribution, density functional theory, molecular dynamics, Monte Carlo Figure : Dealloying of Au-Ag NP to get NPG which has high catalytic activity for COR Figure 1

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Role of solvent in metal-on-metal surface diffusion: A case for rational solvent selection for materials synthesis

Cited by 9 publications

References 35 publications

Kinetic Map for Destabilization of Pt-Skin Au Nanoparticles via Atomic Scale Rearrangements

Kinetic Map for Destabilization of Pt-Skin Au Nanoparticles via Atomic Scale Rearrangements

How the Facet Edge Controls the Overall CO Oxidation in Nanoporous Gold: Combined Atomistic Characterization/DFT Study of Residual Ag Distribution and Catalytic Activity

How the Facet Edge Controls the Overall CO Oxidation in Nanoporous Gold: Combined Atomistic Characterization/DFT Study of Residual Ag Distribution and Catalytic Activity

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