Electrosorption of hydrogen and sulphuric acid anions on single-crystal platinum stepped surfaces. Part I. The [110] zone

The adsorption of hydrogen and sulphuric acid anions has been studied on single-crystal platinum stepped surfaces from the [110] zone. Both processes depend on the orientation of the electrode surface. The multiple states of hydrogen adsorption can be correlated with the nature and density of the adsorption sites. There is a negligible effect of adsorbate-adsorbate interaction. The voltammetric profiles are in a wide potential range determined by bisulphate and sulphate adsorption/desorption. A sharp peak found in voltammetry is associated with hydrogen adsorption in the step sites, composed of the (100)-(111) step-terrace combination, concurrent with sulphate desorption. Bisulphates and sulphates are strongly adsorbed in the trigonal sites in the step, which can be formed from the steps and terraces of different orientations from this zone. The exact position of the adsorbed hydrogen atoms and anions is discussed. A comparison with the adsorption in HClO4 is given for some surfaces