4. Conclusion
A novel nanocomposite material, Ni0.9Zn0.1O/ZnO, has been successfully obtained via the thermal decomposition of mixed pre-cursor compound synthesized using a facile coprecipitation route and its gas sensing properties investigated for many gases (CO, H2and NO2). According to the XRD results the nanocomposite materi-als were a homogeneous mixture of Ni0.9Zn0.1O and ZnO, excludingthe possibility of the simple NiO/ZnO nanocomposite. Enhanced sensing properties with respect to CO were observed by comparison with those of pure Ni0.9Zn0.1O and ZnO structures and the optimal operating temperature was found to be 300◦C. It was alsofound that the as synthesized composite material can be used at lower operating temperature (225◦C) as selective NO2 gas sensor. The humidity has no significant influence on the response of sensor beyond 20%. The heterojunction between Ni0.9Zn0.1O and ZnO and their catalytic activities are probably the principal factor responsible for the enhanced gas sensing performance of the composite material.