Unveiling Pseudocapacitive Charge Storage Behavior in FeWO4 Electrode Material by Operando X-Ray Absorption Spectroscopy

Nicolas Goubard-Bretesché, Olivier Crosnier, Camille Douard, Antonella Iadecola, Richard Retoux, Christophe Payen, Marie Liesse Doublet, Kazuaki Kisu, Etsuro Iwama, Katsuhiko Naoi, Frédéric Favier, Thierry Brousse

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


In nanosized FeWO4 electrode material, both Fe and W metal cations are suspected to be involved in the fast and reversible Faradaic surface reactions giving rise to its pseudocapacitive signature. In order to fully understand the charge storage mechanism, a deeper insight into the involvement of the electroactive cations still has to be provided. The present paper illustrates how operando X-ray absorption spectroscopy is successfully used to collect data of unprecedented quality allowing to elucidate the complex electrochemical behavior of this multicationic pseudocapacitive material. Moreover, these in-depth experiments are obtained in real time upon cycling the electrode, which allows investigating the reactions occurring in the material within a realistic timescale, which is compatible with electrochemical capacitors practical operation. Both Fe K-edge and W L3-edge measurements point out the involvement of the Fe3+/Fe2+ redox couple in the charge storage while W6+ acts as a spectator cation. The result of this study enables to unambiguously discriminate between the Faradaic and capacitive behavior of FeWO4. Beside these valuable insights toward the full description of the charge storage mechanism in FeWO4, this paper demonstrates the potential of operando X-ray absorption spectroscopy to enable a better material engineering for new high capacitance pseudocapacitive materials.

Original languageEnglish
Article number2002855
Issue number33
Publication statusPublished - 2020 Aug 1
Externally publishedYes


  • FeWO
  • X-ray absorption spectroscopy
  • electrochemical capacitors
  • operando
  • pseudocapacitance

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Chemistry(all)
  • Materials Science(all)


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