Enhanced ethanol gas sensing properties of SnO2 nanobelts functionalized with Au

SnO2 nanobelts functionalized with Au were prepared using a three-step process consisting of the thermal evaporation of Sn powders, sputter deposition of Au, and annealing. Multiple-networked sensors were fabricated using Au-functionalized SnO2 nanobelts. Scanning electron microscopy revealed nanobelts with widths ranging from a few hundred nanometers to a few micrometers, thicknesses of a few hundred nanometers, and lengths ranging from a few to a few tens of micrometers coated with the Au nanoparticles with a mean diameter of ∼200 nm. The bare SnO2 nanobelts showed responses of 2.80 and 2.20% to C2H5OH concentrations of 50 and 100 ppm, respectively. In contrast, the Au-functionalized SnO2 nanobelts showed responses of 313.25 and 194.77%, respectively, to the same C2H5OH concentrations. Furthermore, SnO2 nanobelts functionalized with Au showed a higher response than those functionalized with other metal catalysts, such as Pd, Pt and Ag. Both the response and recovery times of the SnO2 nanobelts were decreased slightly by Au-functionalization regardless of the C2H5OH concentration. In addition, this paper discusses the enhanced sensing properties of SnO2 nanobelts functionalized with Au.