Responses of three-dimensional porous ZnO foam structures to the trace level of triethylamine and ethanol

The three-dimensional (3D) porous ZnO foam structures were successfully synthesized by a rapid combustion of ethylene glycol solution of zinc nitrate at 350 and 450 °C. The typical pore diameters of the ZnO foam structures are in the range of 2-5000 nm. The 3D ZnO frameworks are assembled from ZnO nanoparticles with hexagonal structure. The specific surface area and crystallite size of the ZnO foam structures can be adjusted by changing the reaction temperature. The gas-sensing performance of the as-prepared ZnO foam structures was investigated toward ultra low concentrations of triethylamine and ethanol (<5 ppm). It was found that ZnO foam structures obtained at 350 °C shows superior gas-sensing performances, compared with samples obtained at 450 °C, ZnO nanorods and hollow microspheres constructed with ZnO nanorods. The response to 90 ppb of N(C2H5)3 and 210 ppb of C2H5OH 1.40 and 1.24, respectively. The excellent sensing performances are attributed to the 3D porous foam structures with high specific surface area and unique pore structures.