TPD and ITPD study of materials used as chemoresistive gas sensors

Abstract Temperature-programmed desorption (TPD) and a differential form of it, called intermittent temperature-programmed desorption (ITPD), turned out to be powerful characterising techniques for chemoresistive materials applied to gas sensing. We investigated samples of SnO 2 , TiO 2 and solid solutions of them (Ti x Sn 1 −  x O 2 ). TPD and ITPD experiments were carried out in vacuum, with samples previously treated in pure O 2 (100 Torr, 500 °C, 30 min). Amounts of desorbed O 2 corresponded for all Ti-containing samples to less than 10% of a compact monolayer of ions O 2− . Corresponding values of the apparent activation energy of desorption ( E app ) were calculated directly from the Arrhenius plots for each partial TPD and ranged from about 100 to 330 kJ mol − 1 (1.16 to 3.82 eV).