Oxidation of interfacial cobalt controls the pH dependence of the oxygen evolution reaction

Transition metal oxides often undergo dynamic surface reconstruction under oxygen evolution reaction conditions to form the active state, which differs in response to the electrolyte pH. The resulting pH dependency of catalytic activity is commonly observed but poorly understood. Herein we track Co oxidation state changes at different pH-directed (hydr)oxide/electrolyte interfaces using operando X-ray absorption spectroscopy characterizations. Combined with in situ electrochemical analyses, we establish correlations between Co redox dynamics, the flat band potential and Co oxidation state changes to explain the pH dependency of the oxygen evolution activity. Alkaline environments provide a low flat band…

• NS
  National Science Foundation
• SN
  Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung

  Awards: PR00P2_193111, grant No. PR00P2_193111
• PS
  Paul Scherrer Institut
• NC
  National Center of Competence in Research Materials’ Revolution: Computational Design and Discovery of Novel Materials