Linking Bulk and Surface Structures in Complex Mixed Oxides

ACS Catalysis, vol. 14, pp. 9018–9033

Abstract

High Resolution Image Download MS PowerPoint Slide The interface between a solid catalyst and the reacting medium plays a crucial role in the function of the material in catalysis. In the present work, we show that the surface termination of isostructural molybdenum–vanadium oxides is strongly linked to the real structure of the bulk. This conclusion is based on comparing (scanning) transmission electron microscopy images with pair distribution function (PDF) data obtained for (Mo,V)O x and (Mo,V,Te,Nb)O x . Distance-dependent analyses of the PDF results demonstrate that (Mo,V,Te,Nb)O x exhibits stronger deviations from the averaged orthorhombic crystal structure than (Mo,V)O x in the short and intermediate regimes. These deviations are explained by higher structural diversity, which is facilitated by the increased chemical complexity of the quinary oxide and in particular by the presence of Nb. This structural diversity is seemingly important to form intrinsic bulk-like surface terminations that are highly selective in alkane oxidation. More rigid (Mo,V)O x is characterized by defective surfaces that are more active but less selective for the same reactions. In line with machine learning interatomic potential (MLIP) calculations, we highlight that the surface termination of (Mo,V,Te,Nb)O x is characterized by a reconfiguration of the pentagonal building blocks, causing a preferential exposure of Nb sites. The presented results foster hypotheses that chemical complexity is superior for the performance of multifunctional catalysts. The underlying principle is not the presence of multiple chemically different surface centers but instead the ability of structural diversity to optimally align and distribute the elements at the surface and, thus, to shape the structural environment around the active sites. This study experimentally evidences the origin of the structure-directing impact of the real structure of the bulk on functional interfaces and encourages the development of efficient surface engineering strategies toward improved high-performance selective oxidation catalysts.

Authors 13

1. Liudmyla Masliuk

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

2. Kyeonghyeon Nam

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

3. Maxwell W. Terban

   Max Planck Institute for Solid State Research

   Affiliation as printed

   Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany

4. Yonghyuk Lee

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

5. Pierre Kube

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

6. Daniel Delgado

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

7. Frank Girgsdies

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

8. Karsten Reuter

   Fritz Haber Institute of the Max Planck Society

   Affiliation as printed

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

9. Robert Schlögl

   Fritz Haber Institute of the Max Planck Society · Max Planck Institute for Chemical Energy Conversion

   Affiliation as printed

   Department of Heterogeneous Reactions, Max Planck Institute of Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim a.d. Ruhr, Germany

   Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

10. Annette Trunschke

    Fritz Haber Institute of the Max Planck Society

    Affiliation as printed

    Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

11. Christoph Scheurer

    Fritz Haber Institute of the Max Planck Society

    Affiliation as printed

    Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

12. Mirijam Zobel Aachen Institute of Crystallography

    RWTH Aachen University

    Affiliation as printed

    Institute of Crystallography, RWTH Aachen University, Jägerstraße 17-19, 52066 Aachen, Germany

13. Thomas Lunkenbein corresponding

    Fritz Haber Institute of the Max Planck Society

    Affiliation as printed

    Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany