H2sensing characteristics of SnO2coated 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 H2 gas sensing properties were investigated. The SnO2–SWNT network sensors stably and reversibly responded to H2 gas even at room temperature and could detect H2 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.