ИСТИНА

An interrelation between the specific effect of catalytic PdO and RuO2 clusters on the active sites of sol-gel synthesized nanocrystalline tin dioxide and its sensor properties to CO and NH3 was demonstrated. It was shown that PdO increased OH-groups concentration, while RuO2 promoted reactive oxygen species formation on the modified SnO2 surface. This interplay contributes to improving low-temperature SnO2/PdO sensitivity to CO and high NH3 sensitivity of SnO2/RuO2 at raised temperature. The selectivity in these systems was confirmed by measuring the sensors responses to CO+NH3 mixtures. In situ DRIFT studies indicate the key role of catalytic clusters in the selective SnO2/PdO-CO and SnO2/RuO2-NH3 interactions. PdO facilitates low-temperature CO chemisorption followed by its interaction with surface hydroxyl species. RuO2 catalyzes deep NH3 oxidation by chemisorbed oxygen producing NO2 via surface-bound NO formation.