Multiscale atomistic simulation of metal nanoparticles under working conditions

Abstract

Recent theoretical advances in simulating the structural evolution of metal/alloy nanoparticles under working conditions are reviewed, coupled with the qualitative comparison to the experiments and a brief introduction of MOSP software.

Probing Structural Reconstruction of Metal Nanoparticles under Annealing and Water Vapor Conditions: A Theoretical Study

“…The Rh and Ir nanoparticles were modeled using the multiscale operando simulation package (MOSP). 50 The welldefined particle structures of three sizes were constructed with diameter (d) ≈ 3.5 nm, 5.5 nm, and 9.5 nm (measured as the longest distance between two vertices of a truncated octahedron) containing around 1571, 7530, and 31121 atoms, respectively, for complete closure of a NP without creating defects on each facet. The distinctive structures of NPs can be quantified by average atomic coordination number (CN) of surface atoms, which serve as an important morphology parameter:…”

“…As is known, the high Miller index facets have higher surface energy than the low Miller index facets resulting in their negligible contributions to metal NP’s morphology. We thus choose the three low-index facets, i.e., (111), (100), and (110) terraces (with CN i = 9, 8, and 7, respectively), which have been observed to be the most important for defining the shape of fcc-metal NPs and have been commonly employed for exploring their morphology evolution, ,, along with edge and corner sites with CN i = 6 and 5 and atoms in bulk with CN i > 9. The surface atomic concentration (η) of specific coordination number, equivalent to surface sites concentrations, can be used to characterize various adsorption sites and to account for the intrinsic morphological heterogeneity of NPs, defined as The weighted work function (Φ̅) of NP is introduced to provide an additional measure of structural evolution of NPs, defined as where A hkl is the area of all facets of the {hkl} family in the Wulff construction.…”

“…Consequently, theoretical modeling has been commonly evoked to assist the experimental investigation and/or to conduct independent research. 41−49 Recently, the multiscale atomistic simulation approach 50 has gone beyond the pristine NP and the extended surface models in vacuum enabling modeling of metal NPs under working conditions with reliable accuracy. For example, Zhu et al 51 found that the water vapor has different effects on the different metal (Cu, Au, Pt, and Pd) NPs and particularly, the water vapor induces the shape evolution of Cu NP dramatically while the structures of Pd and Pt NPs could also be reshaped under certain water vapor environments.…”

Mapping surface segregation of single-atom Pt dispersed in M surfaces (M = Cu, Ag, Au, Ni, Pd, Co, Rh and Ir) under hydrogen pressure at various temperatures

“…In presence of gas or solvent, and depending on the reaction temperature, the surface composition may change and segregation and/or sintering phenomena may occur. The segregation process leads to an enrichment of one of the alloy components at the surface or into the bulk, while the sintering, governed by the high surface mobility and diffusion of atomically dispersed metal species results in the aggregation of SAAs to form clusters of few atoms on the surface [11][12][13][14][15]. The sintering of singly dispersed metal atoms into clusters and nanoparticles has been observed for many SAAs [16][17].…”

Statistical analysis of homogeneous nucleation of metallic nanoparticles during gas-phase synthesis

“…Kinetic Monte Carlo (KMC) methods, which have gained popularity over the past decades [11][12][13][14][15], do provide a close proximity with experimental data; however, they do not describe the early nucleation stage. KMC methods rest on the assumption that the initial state of the nucleation medium is represented by previously formed and uniformly spatially distributed perfect crystal nuclei, on the surface of which adsorption and desorption processes occur along with the diffusion of monomers in the medium.…”