Nanocrystalline tin dioxide: Basics in relation with gas sensing phenomena part II. Active centers and sensor behavior

Resumo

The experimental data and theoretical concepts on the nature and physicochemical properties of the active centers at the surface of tin dioxide are reported, which are involved in detection of toxic and explosive ambient impurities. The active centers formed at the nanocrystal SnO₂ surface are classified on the basis of their chemical properties, and their role in the interaction of semiconductor nanocrystal oxides with the gases exhibiting the redox properties is confirmed. The chemical modification of the SnO₂ surface aimed at elaborating a controlled amount of specific active centers is shown to be the most efficient method for increasing the selectivity of sensors. Selecting the optimum catalytic modifiers (nanoparticles or clusters of noble metals and their oxides) allows the sensor sensitivity and selectivity of the target gas detection to be increased.