Controllable synthesis of platinum–tin intermetallic nanoparticles with high electrocatalytic performance for ethanol oxidation

Abstract

This article proposes a general approach for the preparation of intermetallic nanoparticles of Pt₃Sn, PtSn, PtSn₂, and PtSn₄, triggered by hexamethyldisilazane (HMDS) in conjunction with SnCl₂. The ethanol oxidation reaction (EOR) tests demonstrate the improved specific activity of Pt_xSn_y intermetallic nanoparticles (Pt_xSn_y), due to the lower binding energy between carbon monoxide (CO) and Pt_xSn_y, the oxidation state of Sn, and the presence of Pt–Sn bonds on the surface. Strikingly, PtSn with an optimized Pt : Sn ratio of 1 : 1 holds superior EOR performance and stability to other Pt_xSn_y intermetallics. In addition, Pt_xSn_y intermetallic nanoparticles including PtSn, PtSn₂, and even the most Sn-rich PtSn₄ hold a higher specific current density than the commercial Pt/C after a long-term test, showing the enhanced stability for the EOR. Furthermore, this method was also successfully extended to the synthesis of other Sn-containing intermetallic nanoparticles, such as Ag₃Sn and Cu₆Sn₅.