Temperature-dependent NO2/diisopropylamine sensor based on SnO2 squama-wrapped tubes derived from waste bamboo shoot skin

Abstract

The development of a conductometric sensor with dual-selectivity remains challenging because most sensors were only reported for sensing a given harmful gas. Accordingly, waste bamboo shoot skin (BSS) was selected as biotemplate and simply immersed in SnCl4 aqueous solution. Then, the obtained BSS precursor was calcined at 600 °C to reproduce biomorphic SnO2-6 squama-wrapped tubes, which achieved temperature-controlled dual-selectivity for two different gases. At a low temperature of 92 °C, SnO2-6 sensor has a super-high response (S = 1300) towards 10 ppm NO2, being obviously larger than most reported metal oxide-based sensors. Also it exhibits a good response (S = 46) towards 100 ppm diisopropylamine (DIPA) at 170 °C for the first time. Such excellent dual-sensing capability mainly relates to the synergism of uniform mesopore distribution, relatively large specific surface area and rich oxygen vacancy defects involved in SnO2-6 squama-wrapped tubes, which not only helps to accelerate rapid gas transport, but also efficiently exposes more active sites, increases the contents of adsorbed oxygen species and promotes surface chemical reactions. Meanwhile, the sensor has reversible response-recovery characteristic, good stability and humidity resistance to both gases. In addition, the dual-functional sensing mechanism was also investigated.