Alexandre Foucher1,Daniel Rosen2,Shengsong Yang2,Christopher B. Murray2,Anatoly Frenkel3,Eric Stach2
Massachusetts Institute of Technology1,University of Pennsylvania2,Stony Brook University, The State University of New York3
Alexandre Foucher1,Daniel Rosen2,Shengsong Yang2,Christopher B. Murray2,Anatoly Frenkel3,Eric Stach2
Massachusetts Institute of Technology1,University of Pennsylvania2,Stony Brook University, The State University of New York3
It is crucial to develop and understand innovative nanocatalysts to improve the efficiency of major catalytic processes and reduce their cost. Intermetallic CuPt has been reported as a promising material as a catalyst for CO oxidation, but changes in structure in a reactive environment at high pressure and temperature are not well described. In this work, we performed an atomic scale <i>in situ</i> scanning transmission electron microscopy (STEM) analysis at 1 bar to track changes in the intermetallic CuPt phase upon oxidation and reduction. These conditions mimic the reactive environment when the CuPt particles are used for catalyzing CO molecules. The atomic structure of the intermetallic phase remained primarily unchanged in 1 bar of O<sub>2</sub> or H<sub>2</sub> at 800 °C, which explains the remarkable stability of the sample. <i>In situ</i> STEM-EELS showed some light oxidation of Cu on the edges of particles upon exposure to O<sub>2</sub> at 800 °C, which can be entirely re-reduced after treatment in H<sub>2</sub> at 800 °C. Thus, partial segregation and oxidation of Cu occur in an oxidative environment but remain limited and can be reversed through annealing. <i>In situ</i> XAS confirms the STEM-EELS results observed and shows that segregation and oxidation of Cu is a generalized trend not limited to the small number of particles studied with in situ STEM. Determining dynamic restructuring effects in CuPt catalysts is valuable information for the improvement and rational design of novel bimetallic catalysts.