Co/ZnO nanorods system for magnetic gas sensing applications

Abstract

Abstract-The ideal chemical gas sensors would provide a device capable of being sensible, selective and stable. To improve the state of the art metal oxide gas sensors two approaches are pursued: obtaining nanosized, single crystalline metal oxide nanorods, and introducing innovative transduction principle. The first approach ensures high surface area for gas interaction coupled with the higher stability. The second approach could overcome limitations on the performances achievable and set a new milestone in the field. In this work magnetic gas sensing tests were carried out, using a MOKE (magneto-optical Kerr effect) magnetometer, showing that it is possible to exploit a new mechanism for sensing devices. The sensing layer, based on Co layer covered by ZnO nanorods, was entirely deposited by RF sputtering. The device showed very good H2 detection at room temperature. The current work focuses on the characterization of the sensing heterostructure based on Co/ZnO nanorods by volumetric magnetization measurements and by MOKE measurements in air and in gas. A model for H2 sensing is also formulated.

Metal Oxide Gas Sensors, a Survey of Selectivity Issues Addressed at the SENSOR Lab, Brescia (Italy)

“…An electron is released back by oxygen desorpting from the surface into the ZnO conduction band and thus is transferred to the Co layer. An increase of the Fermi energy of Co is expected owing to the dn electrons generated in ZnO and entering the Co [ 93 ].…”