Cobalt nanograins effect on the ozone detection by WO3 sensors

A small quantity of cobalt nanograins deposited on the surface of WO3 sensors produces an important change in the WO3 conductance. Indeed, the cobalt changes the conduction type of the sensors from n to p-type. An increase in conductance of the WO3 sensors under ozone is thus observed. This behaviour was investigated for two added quantities of deposited cobalt (15 Å and 30 Å). The modified sensors were tested under ozone before and after an annealing process under dry air at a temperature of 673 K for 1.5 h. The obtained response shape and mechanisms to ozone were explained by chemical reactions related to oxidation of the cobalt incorporated which can probably occur during the annealing process.