FORMIC-ACID DECOMPOSITION ON SNO2(110)

The dissociation and reaction of formic acid on SnO2(110) surfaces was studied using TDS and XPS. Formic acid reacts to form CO, CO2, H2CO and H2O, with the conversion dependent on the initial surface condition. Starting with a stoichiometric surface, the conversion decreases as the surface becomes more oxygen deficient. The variation in conversion is caused by changes in the ability of the surface to dissociate formic acid. Two formate decomposition channels were observed. One channel near 530 K associated with cations near in-plane oxygen anion vacancies forms mainly CO. A second channel near 600 K forms mainly CO2. The results demonstrate the importance of both local surface properties and molecular acidity in controlling acid/base reactions of Bronsted acids on SnO2 surfaces.