A Simple Absorbent Cotton Biotemplate to Fabricate SnO2 Porous Microtubules and Their Gas-Sensing Properties for Chlorine

SnO 2 porous microtubules (PMs) were synthesized by a two-step immersion–calcination method, and absorbent cotton is used as the biotemplate. This method is simple, eco-friendly, and cost-efficient. The absorbent cotton as a biotemplate not only supported the formation of microtubule-like structures but also provided a hypoxia atmosphere to introduce oxygen vacancies in the calcination process. The as-synthesized SnO 2 PMs maintain the morphology of absorbent cotton—long, curly, and twisted. The gas-sensing property of the SnO 2 PMs sensor was systematically investigated for detection of chlorine (Cl 2 ). On the basis of such porous microtubules, the sensor exhibited excellent sensitivity and selectivity to Cl 2 at 200 °C. Compared with SnO 2 particles, the gas response ( R gas / R air ) of the SnO 2 PMs sensor to 10 ppm of Cl 2 at 200 °C was increased about 100 times. Finally, the enhanced gas-sensing performance was associated with the hollow morphology of SnO 2 PMs and the formation of abundant oxygen vacancies because of the decomposition of absorbent cotton.