A Simulation Study on the Structure of Bimetallic Nanoparticles Synthesized in Microemulsions

Monte Carlo simulations were carried out to study the different structures showed by bimetallic nanoparticles synthesized in microemulsions. It is observed that the difference in reduction rates of both metals is not the only parameter to determine the metals segregation, playing the interdroplet channel size a relevant role. The reduction rates difference determines nanoparticle structure only in two extreme cases: when both reactions take place at the same rate a nanoalloy structure is always obtained; if both reactions have very different rates, the nanoparticle shows a core-shell structure. But in the large interval between both extreme cases, the nanoparticle structure is strongly dependent on the intermicellar exchange, which is mainly determined by the surfactant film flexibility, and on reactants concentration. This result is very promising for the preparation of bimetallic nanoparticles with a given structure.