Preparation Of Actinomorphic ZnO/MO?SnO₂,Fe₂O₃? Core-shell Nanocomposites And Their Gas-sensing Properties

In this thesis,actinomorphic ZnO/SnO₂ and ZnO/Fe₂O₃ core-shell nanocomposites were synthesized by a facile two-stage synthesis method.And the gas-sensing properties of the as-prepared materials had been also investigated.The concrete researches content are as follows:1.The actinomorphic ZnO micro-and nanorods were synthesized by a simple chemical solution method.The diameter and length of the ZnO rods are about 0.45¹.5 ?m and 2⁷ ?m,respectively.The impact on the reaction time in the forming process of actinomorphic structures has also been investigated.And the self-assembled mechanism of actinomorphic ZnO hierarchical microstructures has been discussed.2.Actinomorphic ZnO micro-and nanorods were prepared in advance through a chemical solution method,and then a continuous SnO₂ layer with the thickness about 20²5 nm was easily coated on the ZnO rods via an ionic-layer adsorption-reaction method.The effect of the time which steep into alkaline solutions had been investigated.The results indicated the sample which midboby dipping time was 2 min shew the best quality.The gas sensing properties of as-perpared ZnO,SnO₂ and ZnO/SnO₂ were investigated and the result indicated that the ZnO/SnO₂ based sensord possessed much best sensing performance than that of pure ZnO and SnO₂ sensor.This substantial improvement of the response and gas-sensing mechanism of ZnO/SnO₂ nanocomposites can be explained by the space-charge model.3.Actinomorphic ZnO/?-Fe₂O₃ core-shell nanocomposites were synthesized via a facile two-step synthesis method.The gas sensing properties of as-perpared actinomorphic ZnO micro-and nanorods,?-Fe₂O₃ nanoparticles and actinomorphic ZnO/?-Fe₂O₃ core-shell nanocomposites were investigated and the result indicated that the ZnO/?-Fe₂O₃ based sensord possessed much best sensing performance than that of pure ZnO and ?-Fe₂O₃ sensor.The gas-sensing of ZnO/?-Fe₂O₃ nanocomposites can be also explained by the space-charge model.