A comparison of gas-phase and electrochemical measurements for chemisorbed carbon monoxide and hydrogen on platinum crystallites

Abstract

Hydrogen and carbon monoxide chemisorptions have been measured by gas-phase and electrochemical methods for platinum dispersed on carbon supports. At both the liquid and gas-phase interfaces, the stoichiometries of the chemisorptions were similar; the ratio of hydrogen atoms to surface platinum atoms was close to unity, and the ratio of CO molecules to hydrogen atoms adsorbed lay between 0.8 and 1.0 for platinum crystallites up to 200 Å in diameter. In gas-phase measurements, catalyst pretreatment conditions must be carefully controlled to avoid poisoning of the platinum surface. The effectiveness of high anodic potentials in cleaning poisons from the platinum surface makes the electrochemical measurement an attractive complementary technique for the study of platinum supported on carbon.