Effects of a surrounding environment during the coalescence of AuPd nanoparticles

It is far well accepted that the morphology of nanoparticles and nanoalloys is of paramount importance to understand their properties. Furthemore, the morphology depends on the growth mechanism with coalescence generally accepted as one the most common mechanisms both in liquid and in the gas phase. Coalescence refers when two existing seeds collide and aggregate into a larger object. It is expected that the resulting aggregate shows a compact, often spherical structure, although strongly out of the equilibrium, referring to its global minimum. While the coalescence of liquid droplet is widely studied, the first stages of the coalescence between nanoseeds has attracted less interest, although important as multiple aggregation can take place. Here we simulate the coalescence of Au and Pd seeds by the Molecular Dynamics method, comparing the initial stage of the coalescence in vacuum and when there is an interacting surrounding around them. We show that the surface chemical composition of the resulting aggregate depend on the environment as well as the overall morphology.