Role of the Interfaces in Multiple Networked One-Dimensional Core Shell Nanostructured Gas Sensors

This study examined the gas sensing mechanism of multiple networked core shell nanowire sensors. The ethanol gas sensing properties of In2O3/ZnO core shell nanowires synthesized by the thermal evaporation of indium powder in an oxidizing atmosphere followed by the atomic layer deposition of ZnO were examined as an example. The pristine In2O3 nanowires and In2O3-core/ZnO-shell nanowires exhibited responses of similar to 30% and similar to 196%, respectively, to 1000 ppm ethanol at 300 degrees C. The response of the core shell nanostructures to ethanol also showed a strong dependence on the shell layer width. The strongest response to ethanol was obtained with a shell layer thickness of similar to 44 nm corresponding to 2 lambda(D), where lambda(D) is the Debye length of ZnO. The enhanced sensing properties of the core shell nanowires toward ethanol can be explained based on the potential barrier-controlled carrier transport model combined with the surface depletion model; the former is predominant over the latter.