Highly sensitive and fast responding CO sensor based on Co3O4 nanorods

Co3O4 nanorods (diameters ∼6–8 nm and lengths ∼20–30 nm) were synthesized for the first time through a simple co-precipitation/digestion method by calcination of cobalt hydroxyl carbonate in air and their CO gas sensing properties were investigated. The Co3O4 nanorods exhibited outstanding gas sensing characteristics such as, higher gas response (∼6.55–50 ppm CO gas at 250 °C), extremely rapid response (∼3–4 s), fast recovery (∼5–6 s), excellent repeatability, good selectivity and lower operating temperature (∼250 °C). Furthermore, the Co3O4 nanorods are able to detect up to 5 ppm for CO with reasonable sensitivity (∼3.32) at an operating temperature 250 °C and they can be reliably used to monitor the concentration of CO over the range (5–50 ppm). The experimental results clearly demonstrate the potential of using the Co3O4 nanorods as sensing material in the fabrication of CO sensors. Plausible CO sensing mechanism of the Co3O4 nanorods is also discussed.