SO2 sensing properties of SnO2 nanowires grown on a novel diatomite-based porous substrate

Abstract

A pore-forming agent method was adopted to fabricate a novel diatomite-based porous substrate used for preparing SnO2 nanowires (SNWs) as gas sensing materials. The optimal porous substrate with a cristobalite structure was obtained at a graphite content of 40 wt%, and the SNWs were synthesized on the porous substrate by the thermal evaporation method. Structural characterizations by X-ray diffraction and scanning electron microscopy demonstrated that the SNWs grown on the porous substrate had diameters of 20–100 nm and lengths of several hundreds of micrometers, which were thinner, longer and denser than those grown on the dense substrate. The SNWs grown on the porous substrate were found to exhibit a higher SO2 response (Ra/Rg = 33.5–50 ppm) and faster response and recovery times (3 s and 6 s) at a low operating temperature of 85 °C. It revealed that the porous surface of the as-prepared substrate was favorable for the growth of SNWs with a large length-to-diameter ratio and subsequently enhanced their SO2 sensing properties.