Natural arrangement of AgCu bimetallic nanostructures through Oleylamine reduction
Metal-noble-based catalysts are the most used nanomaterials to carry out electrochemical reactions, which are commonly applied in fuel cells. Although this kind of catalyst is expensive and it is worth to mention noble metals are scarce. So, nanocatalysts based on cheaper metals are highly desired. Here, we report the natural arrangement of different AgxCuy nanostrcutures, a potential catalyst to perform oxygen reduction reaction, through oleylamine reduction. Firstly, an experimental study was carried out in order to study the crystallographic structure, size, and shape of each synthesized nanostructure. The samples were fully characterized via powder X-ray diffraction, while scanning-transmission electron microscopy equipped with a high-angle annular dark-field (HAADF) was applied to investigate the morphological features. Interestingly, the HAADF images of the AgCu NPs mostly display a Janus-type configuration, instead of a Core-shell architecture, which is the most stable atomic arrangement.1 Given this, we subsequently performed classical molecular dynamic simulations under the NVT canonical ensemble to deepen further our study. The theoretical results pointed out for the Core-shell morphology as the nanostructure with the lowest energy. However, it also indicates an energy decrease of the Janus configuration, as long as the NPs size increases. Therefore, for nanostructures with a large number of atoms, this could lead to a strong competition between Janus and Core-shell arrangement. Finally, considering the AgCu NPs size, it is worth note the theoretical data supports the experimental results, making these systems interesting not only because of their properties but also due to relatively easy synthesis procedure.