2 FORMS OF CHEMISORBED SULFUR ON PLATINUM AND RELATED STUDIES

The effect of temperature on the potentiodynamic oxidation of adsorbed sulfur layers on platinum, obtained from H2S or SO2 was studied. The broad oxidation peak at 1.2-1.3 V observed at room temperature is resolved at 80°C. Two distinct peaks are observed at 80°C, oxidation peak I (at 0.97 V) corresponding to the weakly bound sulfur and oxidation peak II (at 1.10 V) corresponding to the strongly bound sulfur. Evidence is adduced to show that these two forms of chemisorbed sulfur are distinguished by the number of platinum sites they occupy. At elevated temperatures an extension of the hydrogen region was observed during cathodic charging in the presence of adsorbed sulfur. This phenomenon was found to be reversible with respect to temperature and does not correspond to a desorption of sulfur. © 1979 Elsevier Sequoia S.A.