An in situ grazing incidence X-ray absorption study of ultra thin RuxSey cluster-like electrocatalyst layers

A novel metal chalcogenide cluster material (RuxSey) was investigated in situ using X-ray absorption spectroscopy at grazing angles (GIXAS). The electrocatalyst in form of thin films was deposited onto conducting glass substrates (SnO2:F) from colloidal solution. The detected signal was the result of X-ray reflection from the substrate. The in situ measurements at different atmospheres in the electrochemical system (Ar or N-2, and O-2) as a function of the applied electrode potential provided evidence for surface structure dynamics in electrocatalysis. Although the detected signals were at the limit of detection due to the small quantity of deposited catalyst material, we conclude that the co-ordination of oxygen to the catalytic centres enhances the local disorder. The change in the distance amounts to circa 12% at the vicinity of the ruthenium. This change decreases when changing to N-2 or Ar (non electrocatalytic conditions), therefore, giving strong evidence of reversibility. (C) 2000 Elsevier Science Ltd. All rights reserved.