Highly enhanced response and selectivity of electrospun ZnO-doped SnO2 sensors to ethanol and CO in presence of CH4

In this work, effects of ZnO on response and selectivity of SnO2-based sensors for selective detection of C2H5OH and CO in the presence of CH4 are studied. ZnO-doped SnO2 fibers were synthesized by electrospinning method using SnCl4·5H2O and Zn(CH3COO)2·2H2O as precursors and poly vinyl alcohol (PVA) in distilled water as the polymer solution. The ZnO content and tip-to-collector distance were varied in the range of 0.5–5 wt% and 10–20 cm, respectively. The electrospun samples were dried at 80 °C, calcined at 600 °C, and characterized by SEM, XRD and BET. Diameters of the fibers are in the range of 200–650 nm. The highest BET surface area of 41 m2/g, corresponding to nanoparticle sizes of 21 nm, is obtained for 1.0 wt% ZnO-doped SnO2. The sensors responses were measured in presence of 300 ppm of CO or ethanol and 5000 ppm methane in air at 200–400 °C in a flow system. 1.0 wt% ZnO-doped SnO2 selectively detects both CO and ethanol in presence of methane with the highest responses, while 0.5 wt% one has the highest response to methane. Also the highest surface area of 46 m2/g and sensor response is obtained for SnO2 fibers electrospun at 20 cm tip-to-collector distance.