Oxide-catalyzed growth of Ag2O/Zn2SnO4 hybrid nanowires and their reversible catalytic ambient ethanol/oxygen detection

Large scale hybrid nanowires consisting of Zn2SnO4 periodic nanowires and Ag2O nanoparticles on both nanowire surfaces and tips have been successfully synthesized at 650 degrees C using a unique one-step silver oxide catalyzed vapor-solid-solid (VSS) growth process. The single crystal Zn2SnO4 nanowires mainly grew along the [113] direction with three major morphologies including straight linear, L-shape, and radiative sparse. Two-dimensional nucleation and periodic ledge growth processes were proposed to be responsible for the Zn2SnO4 periodical nanowire formation. These Ag2O/Zn2SnO4 hybrid nanowires were responsive to ethanol at similar to 150 degrees C upon similar to 150 ppm ethanol pulses, with one order of magnitude electrical conductivity decrease. This surprising decrease might be triggered by ethanol pulses associated with Ag2O nanoparticles on nanowire surfaces and electrode-nanowire film interfaces, leading to a catalytic activation of ambient oxygen detection. Ar plasma treatment on the nanowire surface inversely leads to conductivity increase upon ethanol pulses, which suggests a successful plasma removal of catalytic Ag2O and oxygen ions, therefore enabling the detection of ethanol molecules, instead of ambient oxygen. This reversible catalytic ambient ethanol/oxygen detection mechanism enabled by the hybrid nanowire configurations could provide a new path for designing smart gas detection devices compatible with multiple-transient-gas detection.