Key points are not available for this paper at this time.
Bimetallic catalysts typically exhibit superior activity and selectivity compared to single-component catalysts when optimized, inspiring a detailed understanding of the properties of the complex system. Herein, we employed high-resolution X-ray (including synchrotron-based) photoelectron spectroscopy and infrared reflection absorption spectroscopy measurements using CO as the probing molecule to investigate the surface structure of ceria-supported CoCu bimetallic nanoparticles. We found that Co deposition on a Cu-precovered CeO2 surface induces Cu migration to the surface, accompanied by ceria reduction and interfacial Co/CeO2 formation. The lower surface energy of copper than that of cobalt and the stronger interaction of CeO2 with Co than with Cu are possibly responsible for this surface dynamic evolution. This surface structure can be modulated by the introduction of oxygen. A small amount of oxygen exposure effectively promotes the reconstruction of the surface structure by Co migration to the surface of Co/Cu/CeO2, forming cobalt oxides. Our combined spectroscopic results provide direct evidence of the surface structure evolution of CeO2-supported bimetallic nanoparticles under certain conditions.
Zhang et al. (Fri,) studied this question.