Atomic-scale cation dynamics in a monolayer VOX/α-Fe2O3 catalyst

Z. Feng; Q. Ma; J. Lu; H. Feng; J. W. Elam; P. C. Stair; M. J. Bedzyk

doi:10.1039/C5RA18404E

Atomic-scale cation dynamics in a monolayer VO_X/α-Fe₂O₃ catalyst†

Z. Feng,

*^ab Q. Ma,^c J. Lu,^dg H. Feng,^dh J. W. Elam,^d P. C. Stair^e and M. J. Bedzyk*^af

Author affiliations

* Corresponding authors

^a Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
E-mail: z-feng@u.northwestern.edu, bedzyk@northwestern.edu

^b Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, USA

^c DND-CAT, Synchrotron Research Center, Northwestern University, Evanston, IL, USA

^d Energy Systems Division, Argonne National Laboratory, Lemont, IL, USA

^e Department of Chemistry, Northwestern University, Evanston, IL, USA

^f Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA

^g Department of Chemical Physics, University of Science and Technology of China, Jinzhai Road 96#, Baohe District, Hefei, China

^h Xi'an Modern Chemistry Research Institute, 168 E. Zhangba Road, Xi'an, Shaanxi, China

Abstract

Catalytic reactions are associated with dynamical changes in the catalyst that include the oxidation state and local structural variations. The understanding of such dynamics, particularly at the atomic-scale, is of great importance for revealing the activity and selectivity of the catalyst in numerous reactions. Combining in situ X-ray absorption spectroscopy with in situ diffuse reflectance infrared Fourier transform spectroscopy, we studied the redox-induced dynamical changes for a VO_X monolayer catalyst supported on a α-Fe₂O₃ powder. The results show that several co-existing VO_X species reversibly change their V oxidation states between +5 and +4, in concurrence with a structural change from two-dimensional chains to well connected V–O–V networks. These changes are also associated with the breaking and formation of the V [double bond, length as m-dash] O vanadyl group. This combined study provides new insight into how VO_X species change during catalytic reactions, which leads to proposed atomic-scale models for the redox-induced dynamics of the catalyst.

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Article information

DOI: https://doi.org/10.1039/C5RA18404E
Article type: Paper
Submitted: 09 Sep 2015
Accepted: 16 Nov 2015
First published: 18 Nov 2015

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RSC Adv., 2015,5, 103834-103840

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Atomic-scale cation dynamics in a monolayer VO_X/α-Fe₂O₃ catalyst

Z. Feng, Q. Ma, J. Lu, H. Feng, J. W. Elam, P. C. Stair and M. J. Bedzyk, RSC Adv., 2015, 5, 103834 DOI: 10.1039/C5RA18404E

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