**Abstract**

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Nanorods and Nanocomposites

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gold nanoparticles: Potential in

Microbial synthesis of gold nanoparticles using the fungus

colsurfb.2009.07.040

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ZnO nanorods have been widely used to detect low-concentration gases due to its range of conductance variability, response toward both oxidative and reductive gases, and highly sensitive and selective properties. In this chapter, the fabrication methods of ZnO nanorods, their controllable growth, their different configurations, their modification for improving sensing property, and their composites for gas sensors are thoroughly introduced. The synthesis methods to fabricate ZnO nanorods consist of hydrothermal method, microemulsion synthesis, microwaveassisted hydrolysis preparation, gas-solution-solid method, spray pyrolysis, sonochemical route, simple solution route, and so on. The controllable fabrication of ZnO nanorods can be realized by control growth, selective growth, and diameter regulation. Different structures formed by ZnO nanorods include cross-linked configuration, flowerlike structure, and multishelled hollow spheres and hollow microsemispheres, as influence their sensing properties. ZnO nanorods can be modified by doping, functionalization, decoration, and sensitization for enhancing the sensing property. ZnO can be combined with graphene, carbon nanotubes, SnO2, In2O3, and Fe2O3 to form core-shell composites for gas sensor.

**Keywords:** ZnO nanorods, fabrication, modification, composites, gas sensor
