Structural changes of Au–Cu bimetallic catalysts in CO oxidation: In situ XRD, EPR, XANES, and FT-IR characterizations

Au–Cu bimetallic nanoparticles supported on SBA-15 have been reported to be much more active in CO oxidation than the corresponding monometallic counterparts in our previous work. In this work, in situ techniques including XRD, EPR, XANES, and FT-IR were employed to reveal the structural changes of the Au–Cu bimetallic particles during different pretreatment and reaction conditions, and to clarify the essence of the synergistic effect between gold and copper. The results showed that gold remained as Au0 in any treatment conditions, while copper was very sensitive to the treatment temperature and atmosphere. The freshly reduced catalyst was a mixture of Au3Cu1 intermetallic phase and Cu2O amorphous phase. In CO oxidation, the Au3Cu1 intermetallic phase was segregated into a gold core decorated with tiny CuOx patches, and CO adsorbed on Au0 reacted with active oxygen provided by the neighboring CuOx, thus enhancing greatly the activity for CO oxidation.

The structural changes of SBA-15-supported Au–Cu bimetallic nanoparticles were studied by in situ techniques. The freshly reduced catalyst is mainly composed of Au3Cu1 alloy, which was segregated into a gold core decorated with patches of CuOx on the surface during the reaction of CO oxidation.Figure optionsDownload high-quality image (48 K)Download as PowerPoint slideResearch highlights
► The structural changes of Au–Cu/SBA-15 in CO oxidation were studied.
► Au3Cu1 alloy formed by H2 reduction treatment.
► Au3Cu1 was segregated to a gold core decorated with patches of CuOx in CO oxidation.
► CO oxidation proceeds at the perimeter between gold and CuOx patches.
► CuOx played a dual role: anchoring the particles and providing active oxygen.