Studying the formation and the final structure of AuPt bimetallic systems by cyclic voltammetry

Currently, bimetallic nanosystems are some of the most promising materials for catalytic, electrocatalytic and electroanalytical applications, thanks to their novel optical, catalytic, magnetic and sensing properties. However, their characterisation is still a challenge in terms of both the type and the quantity of the metal involved and their structure (e.g. alloyed or core-shell). It is also important to note that these systems underwent modification in time due to the mobility of atoms and the drive to reach the most stable thermodynamic status. In this work, we suggest cyclic voltammetry as a convenient technique for the study of bimetallic nanocomposites and their evolution during the synthetic process. In particular, Pt+Au, Au@Pt and Pt@Au systems have been deeply investigated by comparing their voltammetric results in terms of the shift in the Au and Pt peak potentials and absence/presence of some peaks. Furthermore, the samples were studied with TEM analysis. The results allowed for the discrimination of alloyed and core-shell structures and provided a method to follow changes in the composites during their synthetic preparation. It also enabled the deep analysis of how the two metals interact each other, thereby yielding the peculiar properties that are conveniently used for catalytic purposes.