Bi 2O 3 as a selective sensing material for NO detection

Abstract

In recent years, a growing interest in the development of solid-state gas sensors for combustion exhausts control has arisen. CO 2, CO, partially oxidized reactants, NO and NO 2 are the main gas exhausts components that result from the combustion of organic compounds. The achievement of a cheap, sensitive and selective enough sensing material to monitor these gases is essential. Although large sensitivities are easily obtained with the commonly used semiconductor oxides, e.g. SnO 2, their main problem remains on their lack of selectivity. In this scheme, Bi 2O 3 has been reported to be a good alternative oxide to selectively detect NO. In the present work, the gas sensing properties of different bismuth oxide structures are studied. Sensors obtained from the printing of the Bi 2O 3 nanopowders are observed not to have a perceptible response to CO, CO 2 and hydrocarbons. In the same way, inappreciable resistance variations with the introduction of up to 10 ppm NO 2 are obtained. On the other hand, large enough sensitivities are achieved for NO. Sensing mechanisms of bismuth oxides are further studied at different oxygen partial pressures.