Design of highly sensitive C₂H₅oH sensors using self-assembled ZnO nanostructures

Various ZnO nanostructures such as porous nanorods and two hierarchical structures consisting of porous nanosheets or crystalline nanorods were prepared by the reaction of mixtures of oleic-acid-dissolved ethanol solutions and aqueous dissolved Znprecursor solutions in the presence of NaOH. All three ZnO nanostructures showed sensitive and selective detection of C₂H₅OH. In particular, ultra-high responses (R_a/R_g = ~1,200, R_a: resistance in air, R_g: resistance in gas) to 100 ppm C₂H₅OH was attained using porous nanorods and hierarchical structures assembled from porous nanosheets, which is one of the highest values reported in the literature. The gas response and linearity of gas sensors were discussed in relation to the size, surface area, and porosity of the nanostructures.