Percolating SnO2 nanowire network as a stable gas sensor: Direct comparison of long-term performance versus SnO2 nanoparticle films

A comparative study of the long-term gas-sensing performance of chemiresistors made of: (i) mats of randomly oriented single crystal SnO2 nanowires and (ii) thin layers of pristine SnO2 nanoparticles, has been carried out. The sensing elements made of percolating nanowires demonstrate excellent sensitivity and long-term stability toward traces of 2-propanol in air. Different from the nanowire network, the superior initial sensitivity of the nanoparticle layer deteriorates during the first month of the operation and approaches to one observed steadily in the nanowire mats. The better stability of the nanowire mats sensors is explained in framework of reduced propensity of the single crystal nanowires to sinter under real world operation conditions with respect to nanoparticle thin film. At the microscopic level, the letter defines the stability of the percolating paths, analyte delivery and transduction mechanism in nanowire network sensing elements.