Nitrogen Monoxide Gas Sensing Properties of CuO Nanorods Synthesized by a Hydrothermal Method

We report the nitrogen monoxide (NO) gas sensing properties of p-type CuO-nanorod-based gas sensors. Wesynthesized the p-type CuO nanorods with breadth of about 30 nm and length of about 330 nm by a hydrothermal method usingan as-deposited CuO seed layer prepared on a Si/SiO 2 substrate by the sputtering method. We fabricated polycrystalline CuOnanorod arrays at 80 o C under the hydrothermal condition of 1:1 morality ratio between copper nitrate trihydrate[Cu(NO 2 ) 2 ·3H 2 O] and hexamethylenetetramine (C 6 H 12 N 4 ). Structural characterizations revealed that we prepared the pure CuOnanorod array of a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from thegas sensing measurements that the p-type CuO nanorod gas sensors exhibited a maximum sensitivity to NO gas in dry air atan operating temperature as low as 200 o C. We also found that these CuO nanorod gas sensors showed reversible and reliableelectrical response to NO gas at a range of operating temperatures. These results would indicate some potential applicationsof the p-type semiconductor CuO nanorods as promising sensing materials for gas sensors, including various types of p-njunction gas sensors.Key wordsOxide gas sensor, CuO, nanorod, NO gas, hydrothermal method.