Authors:	Lange, Martin Alexander Krysiak, Yaşar Hartmann, Jens Dewald, Georg Cerretti, Giacomo Tahir, Muhammad Nawaz Panthöfer, Martin Barton, Bastian Reich, Tobias Zeier, Wolfgang G. Mondeshki, Mihail Kolb, Ute Tremel, Wolfgang
Title:	Solid state fluorination on the minute scale : synthesis of WO3−xFx with photocatalytic activity
Online publication date:	5-Aug-2021
Year of first publication:	2020
Language:	english
Abstract:	Solid state reactions are notoriously slow, because the rate-limiting step is diffusion of atoms or ions through reactant, intermediate, and product crystalline phases. This requires days or even weeks of high temperature treatment, consuming large amounts of energy. Metal oxides are particularly difficult to react, because they have high melting points. The study reports a high-speed solid state fluorination of WO3 with Teflon to the oxyfluorides WO3–xFx on a minute (<10 min) scale by spark plasma sintering, a technique that is used typically for a high-speed consolidation of powders. Automated electron diffraction analysis reveals an orthorhombic ReO3-type structure of WO3–xFx with F atom disorder as demonstrated by 19F magic angle spinning nuclear magnetic resonance spectroscopy. The potential of this new approach is demonstrated by the following results. i) Mixed- valent tungsten oxide fluorides WO3–xFx with high F content (0 < x < 0.65) are obtained as metastable products in copious amounts within minutes. ii) The spark plasma sintering technique yields WO3–xFx nanoparticles with high photocatalytic activity, whereas the corresponding bulk phases obtained by conventional solid-state (ampoule) reactions have no photocatalytic activity. iii) The catalytic activity is caused by the microstructure originating from the processing by spark plasma sintering.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-6238
Version:	Published version
Publication type:	Zeitschriftenaufsatz
License:	CC BY-NC-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal:	Advanced Functional Materials 30 13
Pages or article number:	1909051
Publisher:	Wiley-VCH
Publisher place:	Weinheim
Issue date:	2020
ISSN:	1616-3028
Publisher URL:	https://doi.org/10.1002/adfm.201909051
Publisher DOI:	10.1002/adfm.201909051
Appears in collections:	JGU-Publikationen