Facile synthesis of p-type semiconducting cupric oxide nanowires and their gas-sensing properties

Cupric oxide nanowires were successfully synthesized by thermal oxidation of copper wire in air and their gas-sensing properties were investigated. High-resolution transmission electron microscopy (HRTEM) analysis indicated that single crystal CuO nanowires with an average diameter of about 60 nm and length up to several micrometers were grown. The sensor resistance increased upon exposure to reducing gases and decreased with oxidizing gas, indicating p-type semiconducting properties of CuO. The nanowires-based gas sensor could detect a wide range of gases including 1% H2, 60 ppm CO, 60 ppm NH3, and 60 ppm NOx and found a potential application in environmental monitoring.