Impact of particle morphology on surface oxidation of nanoparticles: A kinetic Monte Carlo based study

Abstract

A high‐fidelity coagulation driven kinetic Monte Carlo (KMC) model is developed to study the physics of the nonlinear interplay between competing exothermic collision‐coalescence mediated surface oxidation and complex morphologies in aggregated nanostructures generated during gas‐phase synthesis of nanoparticles. Results suggest a twofold oxidation mechanism in which thermally activated processes form a critical oxide shell, beyond which morphological complexity of nanoparticles gives rise to enhanced oxidation. Simulation results for the example case‐study of Al nanoparticle synthesis in air under different prototypical processing conditions, i.e., temperature, pressure and volume loading, show the efficacy of the model in determining optimal process variables for tuning the structural and chemical makeup of energetic nanomaterials. Finally, it is demonstrated that inclusion of nonisothermal coalescence that leads to the formation of fractal‐like nanoparticles (particularly, < 15 nm) gives rise to higher degrees of oxidation when compared to instantly coalescing spherical particles. © 2012 American Institute of Chemical Engineers AIChE J, 2012

Kinetic Monte Carlo simulation for homogeneous nucleation of metal nanoparticles during vapor phase synthesis

“…This KMC model specifically studies the vapor phase nucleation of Al NPs. The choice of Al NP stems from the growing interest in diverse applications of Al nanomaterials in semiconductors, nanocomposites, and specifically, in energetic nanomaterials for solid‐state combustion studies carried out by numerous earlier experiments and simulations . Table shows the thermophysical properties of Al used for the simulations.…”

“…This work paves the path for our future introduction of more accurate cluster size‐dependent free energy formulations into our current nucleation model. Such a robust model development will facilitate the easy and unified incorporation of the nucleation process into our previously developed KMC‐based collision‐coalescence and morphology‐driven surface oxidation models that can investigate the impact of nucleating critical cluster sizes on the general dynamics of NP growth and evolution without any capillarity and/or, isothermal assumptions.…”

“…, K i,j should be normalized by the sum of all kernels. However, normalizing to K max makes the computational cost less intensive without affecting the accuracy noticeably …”

An Atomistic Molecular Dynamics Study of Titanium Dioxide Adhesion to Lipid Bilayers

“…Intermetallic and metal/metal oxide nanoparticles (NPs) have unique physicochemical and electronic properties that find widespread applications for designing new classes of materials with unique catalytic, energetic, and optical properties. − These properties arise from the dramatic increase in surface area per volume as the size of the particles decreases, leading to surface atoms dominating the NP properties and electron confinement. − The promising properties of NPs have increasingly propelled their use in cosmetics, pigments/paints, pharmaceuticals, and drug delivery applications; however, the biological risks associated with many synthetic NPs have not been comprehensively evaluated…”