Ni0.9Zn0.1O/ZnO nanocomposite prepared by malonate coprecipitation route for gas sensing

tA nanocomposite material, Ni0.9Zn0.1O/ZnO, was synthesized by controlled thermal treatment of thecorresponding nickel zinc malonate previously prepared by coprecipitation in aqueous solution. Theco-existence, structure and morphology of the Zn-doped nickel oxide, Ni0.9Zn0.1O and zinc oxide, ZnO,nanoparticles was confirmed by a set of instrumental techniques such as XRD, SEM and ToF-SIMS. Thegas-sensing properties of the as-synthesized nanocomposites have been evaluated for CO, NO2, H2and theresults show that the gas sensors based on the Ni0.9Zn0.1O/ZnO nanocomposites exhibit a good selectivityto NO2at low temperature (225◦C) and, comparing to ZnO and Ni0.9Zn0.1O individually, an increasein the response to CO gas at a high temperature (300◦C). The significant enhancement of the sensingperformance of the Ni0.9Zn0.1O/ZnO nanocomposite is attributed to the formation of p-n junctions (metaloxide heterojunctions) between Ni0.9Zn0.1O (p-type semiconductor) and ZnO (n-type semiconductor)and to the catalytic activity of these metal oxides.