A Generalized Method for High-Speed Fluorination of Metal Oxides by Spark Plasma Sintering Yields Ta3O7F and TaO2F with High Photocatalytic Activity for Oxygen Evolution from Water

Martin Alexander Lange, Ibrahim Khan, Phil Opitz, Jens Hartmann, Muhammad Ashraf, Ahsanulhaq Qurashi, Leon Prädel, Martin Panthöfer, Antje Cossmer, Jens Pfeifer, Fabian Simon, Marcus von der Au, Björn Meermann, Mihail Mondeshki, Muhammad Nawaz Tahir, Wolfgang Tremel

Research output: Journal PublicationArticlepeer-review

21 Citations (Scopus)

Abstract

A general method to carry out the fluorination of metal oxides with poly(tetrafluoroethylene) (PTFE, Teflon) waste by spark plasma sintering (SPS) on a minute scale with Teflon is reported. The potential of this new approach is highlighted by the following results. i) The tantalum oxyfluorides Ta3O7F and TaO2F are obtained from plastic scrap without using toxic or caustic chemicals for fluorination. ii) Short reaction times (minutes rather than days) reduce the process time the energy costs by almost three orders of magnitude. iii) The oxyfluorides Ta3O7F and TaO2F are produced in gram amounts of nanoparticles. Their synthesis can be upscaled to the kg range with industrial sintering equipment. iv) SPS processing changes the catalytic properties: while conventionally prepared Ta3O7F and TaO2F show little catalytic activity, SPS-prepared Ta3O7F and TaO2F exhibit high activity for photocatalytic oxygen evolution, reaching photoconversion efficiencies up to 24.7% and applied bias to photoconversion values of 0.86%. This study shows that the materials properties are dictated by the processing which poses new challenges to understand and predict the underlying factors.

Original languageEnglish
Article number2007434
JournalAdvanced Materials
Volume33
Issue number20
DOIs
Publication statusPublished - 20 May 2021
Externally publishedYes

Keywords

  • fluorination
  • oxygen evolution reaction
  • photocatalysis
  • spark plasma sintering
  • tantalum oxyfluorides

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering

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