Unexpected gas sensing properties of SiO2/SnO2 core–shell nanofibers under dry and humid conditions

Abstract

SiO₂/SnO₂ core–shell nanofibers were synthesized using TEMPO-oxidized cellulose nanofibers as templates. The gas sensing properties of the synthesized SiO₂/SnO₂ core–shell nanofibers were evaluated under dry and humid conditions and compared to practical SnO₂ nanoparticles produced by a hydrothermal method. The sensor responses were analyzed by monitoring the electric resistance changes upon the introduction of H₂ or CO analytes. Surprisingly, the SiO₂/SnO₂ nanofibers showed a prominent sensor response at a higher temperature at which the adsorbed oxygen on the SnO₂ nanoparticles desorbs under dry conditions. Unexpectedly, the SiO₂/SnO₂ nanofibers are available in humid atmosphere since they are less influenced by H₂O poisoning compared to the SnO₂ nanoparticles. Such an intriguing phenomenon could be interpreted in terms of the lower susceptibility of the major adsorbed oxygen species toward water vapor.