Abstract
In this paper, NO2 sensing by means of single-wall carbon nanotubes (SWCNT) networks, decorated with nanoparticles of TiO2 and Au, is proposed. In particular, it is shown that the performance of these materials can be enhanced using pulsed temperature mode. This sensing strategy effectiveness is theoretically and experimentally assessed. In this paper, in fact, a dynamic model for conductive gas sensors formed by networks of nanowires, considering the junctions between different wires as the main contribution to sensor conductance, and in the presence of the target gas, is presented and validated. The model accounts for variable temperature and gas concentration and sheds some light on the mechanisms leading to the sensor response improvement related to temperature pulsed working mode. It is also shown how the addition of a different material can be modeled through different surface adsorption kinetics.
Highlights
The suitability of single-wall carbon nanotubes (SWCNT)-based materials as sensing layers for toxic gas detection has been widely investigated in the last years [1,2,3,4,5], and recent researches have shown that they can be successfully employed to realize conductive gas sensors with promising performance
The achieved results point out the potentialities of these materials, but a large effort is still needed to reach the exhaustive knowledge of their gas sensing properties [6], which is needed to enable the evolution of commercial solutions employing SWCNT-based sensors
Other hand,the deviation between apredicted andwhich experimental responses conductance of SWCNT networks-based gas sensors working with variable concentration can be higher for measurements with a constant temperature
Summary
The suitability of single-wall carbon nanotubes (SWCNT)-based materials as sensing layers for toxic gas detection has been widely investigated in the last years [1,2,3,4,5], and recent researches have shown that they can be successfully employed to realize conductive gas sensors with promising performance. For SWCNT networks, for instance, it appears possible that the most relevant phenomenon for the sensor response is the influence of adsorbed and charged species on the inter-tube contact barriers within CNT fibers. This assumption is supported by the results obtained by the authors for Metal oxides nanowires bundles in References [13,14,15], the bulk electrical and thermal conductivities of CNT ensembles were found much lower than those of the individual nanotubes.
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