As the water-gas shift (WGS) reaction serves as a crucial industrial process, strategies for developing robust WGS catalysts are highly desiderated. Here we report the construction of stabilized bulk-nano interfaces to fabricate highly efficient copper-ceria catalyst for the WGS reaction. With an in-situ structural transformation, small CeO 2 nanoparticles (2–3 nm) are stabilized on bulk Cu to form abundant CeO 2 -Cu interfaces, which maintain well-dispersed under reaction conditions. This inverse CeO 2 /Cu catalyst shows excellent WGS performances, of which the activity is 5 times higher than other reported Cu catalysts. Long-term stability is also very solid under harsh conditions. Mechanistic study illustrates that for the inverse CeO 2 /Cu catalyst, superb capability of H 2 O dissociation and CO oxidation facilitates WGS process via the combination of associative and redox mechanisms. This work paves a way to fabricate robust catalysts by combining the advantages of bulk and nano-sized catalysts. Catalysts with such inverse configurations show great potential in practical WGS applications.

The metal-support interfaces between metals and oxide supports have long been studied in catalytic applications, thanks to their significance in structural stability and efficient catalytic activity. The metal-rare earth oxide interface is particularly interesting because these early transition cations have high electrophilicity, and therefore good binding strength with Lewis basic molecules, such as H2O. Based on this feature, here we design a highly efficient composite Ni-Y2O3 catalyst, which forms abundant active Ni-NiOx-Y2O3 interfaces under the water-gas shift (WGS) reaction condition, achieving 140.6 μmolCO gcat−1 s−1 rate at 300 °C, which is the highest activity for Ni-based catalysts. A combination of theory and ex/in situ experimental study suggests that Y2O3 helps H2O dissociation at the Ni-NiOx-Y2O3 interfaces, promoting this rate limiting step in the WGS reaction. Construction of such new interfacial structure for molecules activation holds great promise in many catalytic systems.

No abstract

Reactivity of OH and hydride species in oxide-catalyzed hydrogenation reactions has attracted great interest. Herein, we report a combined in situ spectroscopic characterization and density functional theory (DFT) calculation study of ceria-catalyzed acetylene semihydrogenation reaction. The ceria surface is fully hydroxylated during the adopted reaction condition. C2H2 adsorbs molecularly on the stoichiometric CeO2 surface and hydrogenates with OH groups selectively to produce C2H4. Semihydrogenation of C2H2 to C2H4 with either OH groups or hydride species on ceria surfaces with surface oxygen vacancies proceeds more facilely than on a stoichiometric CeO2 surface, but C2H4 adsorbs more strongly and further hydrogenates to C2H6 more facilely; moreover, dissociative adsorption of C2H2 to C2H species occurs, which facilely hydrogenates with the hydride species eventually to form C2H6 and react with each other to produce oligomers, decreasing the catalytic selectivity and stability, respectively. These results demonstrate that the ceria catalyst with a stoichiometric surface is extremely selective in catalyzing C2H2 semihydrogenation reaction to C2H4, whereas surface oxygen vacancies or hydride species on ceria are harmful to the catalytic performance.