Probing Surface Structures of CeO 2 , TiO 2 , and Cu 2 O Nanocrystals with CO and CO 2 Chemisorption

CO and CO 2 chemisorption on uniform CeO 2, TiO 2, and Cu 2 O nanocrystals with various morphologies were comprehensively studied with in-situ diffuse reflectance infrared Fourier transform spectroscopy. The formed adsorbates were observed to be morphology dependent. CO or CO 2 chemisorbed at the metal cation sites, and bidentate and bridged carbonates involving the O sites are sensitive to the surface composition and the local coordination environments of surface metal cations and O anions and can be correlated well with the surface structures of facets exposed on oxide nanocrystals. Carbonate and carbonite species formed by CO chemisorption can probe the different facets of CeO 2 . Carbonate species formed by CO chemisorption can probe the different facets of TiO 2 . Adsorbed CO and carbonate species formed by CO chemisorption can probe the different facets of Cu 2 O, and adsorbed CO 2 formed by CO 2 chemisorption can also probe the different facets of Cu 2 O. These results demonstrate chemisorption of probing molecules as a convenient technique to identify surface structures of different facets of oxide nanocrystals and lay the foundations of surface structures for the fundamental understanding of catalysis and other surface-mediated functions of CeO 2, TiO 2, and Cu 2 O nanocrystals.