No abstract

Metal nanoparticles usually show different oxidation dynamics from bulk metals, which results in various oxide nanostructures because of their sizerelated surface effects. In this work, we have found and investigated the chain-like nucleation and growth of oxides on the aluminum nanoparticle (ANP) surface, using molecular dynamics simulations with the reactive force-field (ReaxFF). After nucleation, the chain-like oxide nuclei could stay on the ANP surface and continue growing into an oxide shell, extend outward from the surface to form longer oxide chains, or detach from the ANP to generate independent oxide clusters, which is highly dependent on the oxygen content, temperature, and nanoparticle size. Our results emphasize the complicated interplay between the surface structure of nanoparticles and the environmental conditions in determining the formation of oxides, which provides insights into the atomic-scale oxidation mechanism of metal nanoparticles.

Polarizable shell-model potentials are widely used for atomic-scale modeling of charged defects in solids using the Mott–Littleton approach and hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) embedded-cluster techniques. However, at the pure MM level of theory, the calculated defect energetics may not satisfy the requirement of quantitative predictions and are limited to only certain charged states. Here, we proposed a novel interatomic potential development scheme that unifies the predictions of all relevant charged defects in CeO2 based on the Mott–Littleton approach and QM/MM electronic-structure calculations. The predicted formation energies of oxygen vacancies accompanied by different excess electron localization patterns at the MM level of theory reach the accuracy of density functional theory (DFT) calculations using hybrid functionals. The new potential also accurately reproduces a wide range of physical properties of CeO2, showing excellent agreement with experimental and other computational studies. These findings provide opportunities for accurate large-scale modeling of the partial reduction and nonstoichiometry in CeO2, as well as a prototype for developing robust interatomic potentials for other defective crystals.

No abstract

Graphene oxidation proceeds in a symmetrical manner on the vacancy. Disordered rings on grain boundaries self-restructure.