Size- and composition-controlled Pt–Sn bimetallic nanoparticles prepared by atomic layer deposition

Abstract

Pt–Sn bimetallic nanoparticles (BMNPs) are used in a variety of catalytic reactions and are widely accepted as a model system for Pt-based bimetallics in fundamental catalysis research. Here, Pt–Sn BMNPs were prepared via a two-step synthesis procedure combining atomic layer deposition (ALD) and temperature programmed reduction (TPR). In situ X-ray diffraction measurements during TPR and ex situ X-ray absorption spectroscopy at the Pt L_III-edge revealed the formation of Pt–Sn bimetallic alloys with a phase determined by the Pt/(Pt + Sn) atomic ratio of the as-deposited bilayer. The size of the BMNPs could be tuned by changing the total thickness of the bilayers, while keeping the Pt/(Pt + Sn) atomic ratio constant. Due to the exceptional control over BMNP size and crystalline phase, the proposed method will enable highly systematic studies of the relation between the structure and the performance of Pt–Sn bimetallic catalysts.