Ozone reactivity with carbon nanotubes: experimental and theoretical studies

Carbon nanotubes (CNTs) thin films have been investigated as new O₃ gas sensors in the concentration range 75 - 200 ppb. 150 nm thick CNTs thin films, have been prepared by rf-PECVD on Si/Si₃N₄ substrates, provided with Pt interdigital electrodes, and post-annealed under controlled conditions. The electrical response to O₃ has been investigated at different operating temperatures starting from the room temperature. Sensitivity response analysis has demonstrated that CNTs are responsive to O₃ with a decrease of the baseline resistance similar to that observed for NO₃. In order to obtain a theoretical validation of the experimental results, the equilibrium position, charge transfer and density of states have been calculated from first principles for the CNT+O₃ system.