Single-atom catalysts maximize the utilization of supported precious metals by exposing every single metal atom to reactants. To avoid sintering and deactivation at realistic reaction conditions, single metal atoms are stabilized by specific adsorption sites on catalyst substrates. Here we show by combining photoelectron spectroscopy, scanning tunnelling microscopy and density functional theory calculations that Pt single atoms on ceria are stabilized by the most ubiquitous defects on solid surfaces--monoatomic step edges. Pt segregation at steps leads to stable dispersions of single Pt(2+) ions in planar PtO4 moieties incorporating excess O atoms and contributing to oxygen storage capacity of ceria. We experimentally control the step density on our samples, to maximize the coverage of monodispersed Pt(2+) and demonstrate that step engineering and step decoration represent effective strategies for understanding and design of new single-atom catalysts.

Charles University Prague Faculty of Mathematics and Physics 5 Holešovičkách 2 Prague 18000 Czech Republic

CNR IOM DEMOCRITOS Istituto Officina dei Materiali Consiglio Nazionale delle Ricerche Via Bonomea 265 Trieste 34136 Italy

SISSA Scuola Internazionale Superiore di Studi Avanzati Via Bonomea 265 Trieste 34136 Italy

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Yang X. et al. Single-atom catalysts: a new frontier in heterogeneous catalysis. Acc. Chem. Res. 46, 1740–1748 (2013). PubMed

Flytzani-Stephanopoulos M. & Gates B. C. Atomically dispersed supported metal catalysts. Annu. Rev. Chem. Biomol. Eng. 3, 545–574 (2012). PubMed

Fu Q., Saltsburg H. & Flytzani-Stephanopoulos M. Active nonmetallic Au and Pt species on ceria-based water-gas shift catalysts. Science 301, 935–938 (2003). PubMed

Bruix A. et al. Maximum noble-metal efficiency in catalytic materials: atomically dispersed surface platinum. Angew. Chem. Int. Ed. 53, 10525–10530 (2014). PubMed

Qiao B. et al. Single-atom catalysis of CO oxidation using Pt PubMed

Novotný Z. et al. Ordered array of single adatoms with remarkable thermal stability: Au/Fe PubMed

Parkinson G. S. et al. Carbon monoxide-induced adatom sintering in a Pd-Fe PubMed

Bliem R. et al. Subsurface cation vacancy stabilization of the magnetite (001) surface. Science 346, 1215–1218 (2014). PubMed

Li F., Li Y., Zeng X. C. & Chen Z. Exploration of high-performance single-atom catalysts on support M

Hatanaka M. et al. Ideal Pt loading for a Pt/CeO

Fiala R. et al. Proton exchange membrane fuel cell made of magnetron sputtered Pt–CeO

Gong X.-Q., Selloni A., Batzill M. & Diebold U. Steps on anatase TiO PubMed

Barth J. V, Costantini G. & Kern K. Engineering atomic and molecular nanostructures at surfaces. Nature 437, 671–679 (2005). PubMed

Vang R. T. et al. Controlling the catalytic bond-breaking selectivity of Ni surfaces by step blocking. Nat. Mater. 4, 160–162 (2005). PubMed

Gong X., Selloni A., Dulub O., Jacobson P. & Diebold U. Small Au and Pt clusters at the anatase TiO PubMed

Dvořa´k F. et al. Adjusting morphology and surface reduction of CeO

Duchoň T. et al. Ordered phases of reduced ceria as epitaxial films on Cu(111). J. Phys. Chem. C 118, 357–365 (2014).

Zhou Y., Perket J. M. & Zhou J. Growth of Pt nanoparticles on reducible CeO

Shao X., Jerratsch J.-F., Nilius N. & Freund H.-J. Probing the 4f states of ceria by tunneling spectroscopy. Phys. Chem. Chem. Phys. 13, 12646–12651 (2011). PubMed

Lu J.-L., Gao H.-J., Shaikhutdinov S. & Freund H.-J. Morphology and defect structure of the CeO

Zhou Y. & Zhou J. Interactions of Ni nanoparticles with reducible CeO

Mullins D. R. et al. Water dissociation on CeO

Bruix A. et al. A new type of strong metal-support interaction and the production of H PubMed

Negreiros F. R. & Fabris S. Role of cluster morphology in the dynamics and reactivity of subnanometer Pt clusters supported on ceria surfaces. J. Phys. Chem. C 118, 21014–21020 (2014).

Kozlov S. M., Viñes F., Nilius N., Shaikhutdinov S. & Neyman K. M. Absolute surface step energies: accurate theoretical methods applied to ceria nanoislands. J. Phys. Chem. Lett. 3, 1956–1961 (2012).

Torbrügge S., Cranney M. & Reichling M. Morphology of step structures on CeO

James T. E., Hemmingson S. L. & Campbell C. T. Energy of supported metal catalysts: from single atoms to large metal nanoparticles. ACS Catal. 5, 5673–5678 (2015).

James T. E., Hemmingson S. L., Ito T. & Campbell C. T. Energetics of Cu adsorption and adhesion onto reduced CeO

Colussi S. et al. Nanofaceted Pd-O sites in Pd-Ce surface superstructures: Enhanced activity in catalytic combustion of methane. Angew. Chem. Int. Ed. 48, 8481–8484 (2009). PubMed

Kozlov S. M. & Neyman K. M. O vacancies on steps on the CeO PubMed

Fiala R. et al. Pt–CeO

Hatanaka M. et al. Reversible changes in the Pt oxidation state and nanostructure on a ceria-based supported Pt. J. Catal. 266, 182–190 (2009).

Nagai Y. et al. Sintering inhibition mechanism of platinum supported on ceria-based oxide and Pt-oxide-support interaction. J. Catal. 242, 103–109 (2006).

Matolín V. et al. Platinum-doped CeO PubMed

Zhou J., Baddorf A. P., Mullins D. R. & Overbury S. H. Growth and characterization of Rh and Pd nanoparticles on oxidized and reduced CeO

Zhou Y., Perket J. M. & Zhou J. Growth of Pt nanoparticles on reducible CeO

Zhou Y. & Zhou J. Growth and sintering of Au−Pt nanoparticles on oxidized and reduced CeO

Sayle T. X. T., Parker S. C. & Sayle D. C. Oxidising CO to CO PubMed

Castellani N. J., Branda M. M., Neyman K. M. & Illas F. Density functional theory study of the adsorption of Au atom on cerium oxide: effect of low-coordinated surface sites. J. Phys. Chem. C 113, 4948–4954 (2009).

Zambelli T., Wintterlin J., Trost J. & Ertl G. Identification of the ‘active sites' of a surface-catalyzed reaction. Science 273, 1688–1690 (1996).

Matolín V. et al. Water interaction with CeO

Mullins D. R. The surface chemistry of cerium oxide. Surf. Sci. Rep. 70, 42–85 (2015).

Cococcioni M. & de Gironcoli S. Linear response approach to the calculation of the effective interaction parameters in the LDA+U method. Phys. Rev. B 71, 035105 (2005).

Perdew J. P. J., Burke K. & Ernzerhof M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996). PubMed

Vanderbilt D. Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. Phys. Rev. B 41, 7892–7895 (1990). PubMed

Giannozzi P. et al. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. J. Phys. Condens. Matter 21, 395502 (2009). PubMed

Fabris S., de Gironcoli S., Baroni S., Vicario G. & Balducci G. Taming multiple valency with density functionals: a case study of defective ceria. Phys. Rev. B 71, 041102 (2005).

Fabris S., Vicario G., Balducci G., De Gironcoli S. & Baroni S. Electronic and atomistic structures of clean and reduced ceria surfaces. J. Phys. Chem. B 109, 22860–22867 (2005). PubMed

p-Type TiO2 Nanotubes: Quantum Confinement and Pt Single Atom Decoration Enable High Selectivity Photocatalytic Nitrate Reduction to Ammonia

CO oxidation by Pt2/Fe3O4: Metastable dimer and support configurations facilitate lattice oxygen extraction