Voltammograms of stepped and kinked stepped surfaces of palladium: Pd(S)-[n(111)×(100)] and Pd(S)-[n(100)×(110)]

Voltammograms of stepped and kinked stepped surfaces of Pd (Pd(S)-[n(111)×(100)] and Pd(S)-[n(100)×(110)]) were measured in 0.5 M H2SO4. Both series gave redox peaks around 0.25 V (RHE) for which the intensity decreases with the decrease of the terrace width in 0.5 M H2SO4. No peak was observed around 0.25 V in 0.1 M HClO4. In the oxide film formation region, Pd(S)-[n(111)×(100)] and Pd(S)-[n(100)×(110)] electrodes gave single anodic peaks at 1.1 and 0.9 V (RHE), respectively. The peak intensity diminished with the decrease of the terrace width. Both series presented no peak for which the intensity was enhanced with the increase of step atom density. Charges of the anodic peaks equaled those calculated on the assumption that a monolayer of the oxide film (Pd–OH or Pd2O) covers the entire terrace.