Effect of ceria surface facet on stability and reactivity of isolated platinum atoms  

作　　者：Bochuan Song Shuxin Si Asiye Soleymani Yan Xin Helena E.Hagelin-Weaver 

机构地区：[1]Department of Chemical Engineering,University of Florida,Gainesville 32611,USA [2]National High Magnetic Field Laboratory,Florida State University,Tallahassee 32310,USA

出　　处：《Nano Research》2022年第7期5922-5932,共11页纳米研究（英文版）

基　　金：supported by the National Science Foundation(NSF)(CHE-1507230 and CBET-1933723);the National High Magnetic Field Laboratory,which is supported by the NSF Cooperative Agreement(DMR-1644779)and the State of Florida.Startup funding from the University of Florida is also gratefully acknowledged.

摘　　要：Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface facets.In contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria shapes.To isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation conditions.The isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) rods.In the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the support.On the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt species.In addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on stream.The isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) surface.The Pt supported on the CeO_(2) rods is also remarkably stable with time on stream.This work demonstrates t

关 键 词：single atom catalyst CeO_(2)shapes facet effects Pt1/CeO_(2) diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) 

分 类 号：O64[理学—物理化学] TB3[理学—化学]