Highly sensitive VOCs-acetone sensor based on Ag-decorated SnO2 hollow nanofibers

A certain amount of silver (Ag)-decorated tin dioxide (SnO2) hollow nanofibers are successfully synthesized by electrospinning technique followed by silver nitrate (AgNO3) treatment at 200 °C for 2 h in air. The crystallization, element composition, microstructure and morphology are investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) method, respectively. The characterizations show that the crystalline Ag/SnO2 composites have porous tubular structure with inside diameters of about 220 nm and lengths of several ten microns. The gas-sensing measurements indicate that the Ag-decorated SnO2 sensor based on the SnO2 hollow nanofibers shows high response, fast response-recovery capability and excellent selectivity to acetone at low operating temperature of 160 °C. The sensor can effectively detect the low concentration of acetone vapor (about 5 ppm), and the response and recovery time to 50 ppm acetone are around 6 s and 10 s, respectively. The remarkable improvement in gas sensing properties is attributed to the unique 1D hollow nanostructure, the outstanding catalytic oxidation activity of noble metals and p-n hetero interface formed between p-type Ag2O and n-type SnO2.