H2 sensing characteristics of SnO2 coated single wall carbon nanotube network sensors

SnO2 nanoparticle coated single wall nanotube (SWNT) network sensors were fabricated by forming a SWNT network on the Pt patterned SiO2/Si substrate using a dip coating method and subsequently depositing SnO2 nanoparticles on the SWNT network by rf magnetron sputtering. Their H-2 gas sensing properties were investigated. The SnO2-SWNT network sensors stably and reversibly responded to H-2 gas even at room temperature and could detect H-2 gas down to 100 ppm. In addition to the low temperature detection, a remarkable finding was that the gas sensing behavior of SnO2-SWNT network sensors was changed from p-type to n-type with increasing SnO2 deposition time (i.e. surface coverage of SnO2 on SWNT). A schematic model was proposed to explain the switching of sensing behavior depending on the surface coverage of SnO2 nanoparticles on the SWNTs.