In situ and operando observation of surface oxides during oxygen evolution reaction on copper


TOPARLI Ç., Sarfraz A., Wieck A. D., Rohwerder M., Erbe A.

ELECTROCHIMICA ACTA, cilt.236, ss.104-115, 2017 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 236
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1016/j.electacta.2017.03.137
  • Dergi Adı: ELECTROCHIMICA ACTA
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.104-115
  • Anahtar Kelimeler: Defect formation, Passivity, Transpassivity, Oxygen evolution reaction, Copper oxides, ELECTROCHEMICAL EVOLUTION, ELECTRONIC-STRUCTURE, RAMAN-SPECTROSCOPY, STAINLESS-STEELS, PASSIVE COPPER, FILM FORMATION, INITIAL-STAGES, BIPOLAR MODEL, COBALT OXIDE, NICKEL-OXIDE
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

Formation and dissolution of oxide on copper under transpassive conditions, i.e. during OER and transpassive dissolution, in alkaline electrolyte was investigated by a combination of electrochemical techniques and in situ and operando Raman and photoluminescence (PL) spectroscopy, as well as spectropscopic ellipsometry. Experiments were conducted under potentiodynamic and potentiostatic polarisation in 0.1M NaOH. In chronoamperometry experiments with steps between potentials, oxide thickness continued increasing beyond the onset of OER. The thickness dropped significantly from >10 nm to <5 nm approximate to 400 mV above the OER onset. The presence of CuO, Cu2O and Cu4O3 was observed by Raman spectroscopy after the onset of OER. Correlating with the thickness drop, strong PL was observed at 1.55 eV, indicating the formation of singly charged oxygen vacancies V-O(+), following the classical PL spectrum interpretation from the literature. PL observation speaks against vacancy pair coalescence as mechanism of dissolution. After electrochemical experiments, the films were n-type semiconductors, not p-type conductors as expected for copper oxides. Results indicate that transpassive dissolution may be triggered by the instability of the oxide with respect to defect formation. (C) 2017 Elsevier Ltd. All rights reserved.