Synthesis and Characterization of Stable Cu–Pt Nanoparticles under Reductive and Oxidative Conditions
Alexandre C. Foucher, Shengsong Yang, Daniel J. Rosen, Renjing Huang, Jun Beom Pyo, Ohhun Kwon, Cameron J. Owen, Darío Ferreira Sánchez, Ilia I. Sadykov, Daniel Grolimund, Boris Kozinsky, Anatoly I. Frenkel, Raymond J. Gorte, Christopher B. Murray, Eric A. Stach
Abstract
We report a synthesis method for highly monodisperse Cu–Pt alloy nanoparticles. Small and large Cu–Pt particles with a Cu/Pt ratio of 1:1 can be obtained through colloidal synthesis at 300 °C. The fresh particles have a Pt-rich surface and a Cu-rich core and can be converted into an intermetallic phase after annealing at 800 °C under H 2 . First, we demonstrated the stability of fresh particles under redox conditions at 400 °C, as the Pt-rich surface prevents substantial oxidation of Cu. Then, a combination of in situ scanning transmission electron microscopy, in situ X-ray absorption spectroscopy, and CO oxidation measurements of the intermetallic CuPt phase before and after redox treatments at 800 °C showed promising activity and stability for CO oxidation. Full oxidation of Cu was prevented after exposure to O 2 at 800 °C. The activity and structure of the particles were only slightly changed after exposure to O 2 at 800 °C and were recovered after re-reduction at 800 °C. Additionally, the intermetallic CuPt phase showed enhanced catalytic properties compared to the fresh particles with a Pt-rich surface or pure Pt particles of the same size. Thus, the incorporation of Pt with Cu does not lead to a rapid deactivation and degradation of the material, as seen with other bimetallic systems. This work provides a synthesis route to control the design of Cu–Pt nanostructures and underlines the promising properties of these alloys (intermetallic and non-intermetallic) for heterogeneous catalysis.