Molecular dynamics simulation of Pt@Au nanoalloy in various solvents: Investigation of solvation, aggregation, and possible coalescence

In this study, a pair of core-shell Pt@Au nanoalloy particles with 309 atoms was simulated in various solvents, including water, benzene, ethanol, water + benzene, and 1-butyl-1,1,1-trimethylammonium methanesulfonate [N1114][C1SO3] ionic liquid (IL) at 300 K and 1 atm. We investigated the aggregation and possible coalescence of Au–Pt nanoalloys based on various thermodynamic, dynamic, and structural simulation results. The findings from our study demonstrated that the tendency for aggregation of nanoalloys is greater in water and benzene + water systems than in other solvents. This tendency is weaker in the solvents such as IL, ethanol, and benzene (weakest in benzene). Our results also showed that there is a very small change in the structure of the nanoalloys in the different solvents even after 100 ns of simulation time. Furthermore, coalescence does not occur between the two (Pt@Au)309 nanoalloys. Our results also indicated that the nanoalloys have lower solvation energy in water than in the other solvents. It is also found that IL has a higher solvation energy compared to other solvents. The dynamic results indicated that the (Pt@Au)309 nanoalloys have higher self-diffusion coefficients in benzene and lower diffusion values in IL. Furthermore, we examined the effects of nanocluster shape and core by simulating truncated octahedral (Au)374 and pure icosahedral (Au)309 nanoclusters in water. The results showed that despite the (Pt@Au)309 nanoalloy, the two pure icosahedral (Au)309 nanoclusters approached each other, and coalescence occurred.