Nanoengineered chemiresistors:: the interplay between electron transport and chemisorption properties of morphologically encoded SnO2 nanowires

The transport properties and gas-sensing performance of chemiresistors based on quasi-1D, single-crystal, SnO2 nanostructures with deliberately synthesized ( encoded) segmented morphology are explored. Such nanostructures were obtained using programmable modulation of the gas supersaturation ratio during their growth. Using hydrogen and oxygen as model reducing and oxidizing gases, we show that the responsiveness of these structurally modulated nanowires to gases is improved over that of straight nanowires of the same average diameter. This is due to the presence of small-diameter segments, which dominate the nanostructure's transport properties and to the better tolerance of such nanostructures towards contact effects. The narrow segments approximate the excellent responsiveness of 'necks' between particles in traditional thin film gas sensors but with the significant advantage of greater morphological integrity and stability.