title: Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation.
abstract: Finding ideal material models for studying the role of catalytic active sites remains a great challenge. Here we propose pits confined in an atomically thin sheet as a platform to evaluate carbon monoxide catalytic oxidation at various sites. The artificial three-atomic-layer thin cerium(IV) oxide sheet with approximately 20% pits occupancy possesses abundant pit-surrounding cerium sites having average coordination numbers of 4.6 as revealed by X-ray absorption spectroscopy. Density-functional calculations disclose that the four- and five-fold coordinated pit-surrounding cerium sites assume their respective role in carbon monoxide adsorption and oxygen activation, which lowers the activation barrier and avoids catalytic poisoning. Moreover, the presence of coordination-unsaturated cerium sites increases the carrier density and facilitates carbon monoxide diffusion along the two-dimensional conducting channels of surface pits. The atomically thin sheet with surface-confined pits exhibits lower apparent activation energy than the bulk material (61.7 versus 122.9 kJ mol(-1)), leading to reduced conversion temperature and enhanced carbon monoxide catalytic ability.
authors.affiliation: 1] Hefei National Laboratory for Physical Sciences at Microscale, Collaborative Innovation Centre of Chemistry for Energy Materials, University of Science and Technology of China, Hefei 230026, China [2].
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Sun
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Liu
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.forename: Fengcai
authors.initials: F
authors.lastname: Lei
authors.forename: Zhihu
authors.initials: Z
authors.lastname: Sun
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Haibin
authors.initials: H
authors.lastname: Su
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D017356:Synchrotrons; D056928:X-Ray Absorption Spectroscopy
chemical_list: D002563:Cerium; C030583:ceric oxide; D002248:Carbon Monoxide