Structure and adsorption properties of Cu-Au nanoparticles in harsh reactive environments

AA Mikhailova and AP Maltsev and PCD Mendes and FB Zamudio and AR Oganov and SM Kozlov, JOURNAL OF CHEMICAL PHYSICS, 163, 124302 (2025).

DOI: 10.1063/5.0288099

The reactivity of nanoparticles is governed by their surface composition, which tends to vary significantly under reactive conditions. In this study, the impacts of temperature and the presence of a CO or O-2 atmosphere on the structures of Au-79, Cu19Au60, Cu39Au40, Cu60Au19, and Cu-79 nanoparticles were investigated using a combination of global optimization, machine learning interatomic potentials, and density functional theory. We find that increasing gold content weakens CO and O adsorption and limits oxygen-induced structural changes, while copper-rich particles undergo pronounced oxidation and reconstruction. Bader charge analysis shows that, in bare nanoalloys, Au withdraws electron density from Cu due to their electronegativity difference. In oxidized Cu-Au nanoalloys, the charge on Cu atoms depends on the number of O neighbors and can reach values typical of Cu2O (0.6 e) and CuO (1.1 e). On average, the Cu atoms exhibit positive effective Bader charges of similar to 0.9 e in these nanoalloys. Our results indicate that models of Cu-Au catalysts under oxidizing conditions must incorporate the full ensemble of metallic and oxidized configurations rather than a single most probable structure to predict true catalytic activity.

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