Improved acetone sensing properties of flat sensors based on Co-SnO2 composite nanofibers

Abstract

Co-SnO 2 composite nanofibers were synthesized by an electrospinning method and characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Gas sensors were fabricated by spinning these nanofibers onto flat ceramic substrates, which had signal electrodes and heaters on their top and bottom surfaces, respectively. Compared with sensors loaded with pure SnO 2 nanofibers, the Co-SnO 2 nanofiber sensors exhibited improved acetone sensing properties with high selectivity and rapid response and recovery times. The response was 33 when the sensors were exposed to 100 μL/L acetone at 330°C, and the corresponding response with 100 μL/L of ethanol was only 6. The response and recovery times to acetone were about 5 and 8 s, respectively. These results indicate Co-SnO 2 composite nanofibers are good candidates for fabrication of high performance acetone sensors for practical application. Establishing effective methods for monitoring and detecting toxic and flammable gases such as carbon monoxide, acetone, benzene and toluene is important because of the regulations that exist in many countries [1][2][3][4][5]. Although many modern monitoring methods, such as gas chromatography and infrared spectroscopy, have high sensitivity, they are expensive and cannot be used for real-time measurements. Recently, semiconductor oxide-based gas sensors have attracted attention because of their good reproducibility, compact size, ease of use, and low cost [6,7]. However, the response time of these sensors is difficult to improve and their selectivity is low. The main reason for these problems is that the sensing reaction of these sensors is based on chemisorbed oxygen species on the sensor surface, and it is difficult to manipulate these oxygen species for specific outcomes [1]. The sensing performance is also based on the operating temperature, sensor structure, and material morphology. The interaction of these parameters is complex, and this makes it difficult to control or improve the semiconductor oxide-based gas sensors [8][9][10]. Recently, onedimensional (1D) semiconductor oxides have received considerable attention because of their controllable diameter, high density of surface sites, and large surface-to-volume ratios. Many high performance gas sensors have been produced with rapid response/recovery times and high sensitivities [11][12][13]. Several Chinese groups have published a series of sensing results based on these 1D semiconductor oxides [12,13]. However, most of these sensors were fabricated by grinding the 1D semiconductor oxides into pastes and then coating the paste on the surface of ceramic tubes [7]. These processes would damage the morphology and structure of the oxides, and subsequently decrease the performance of the sensor. There have been few investigations on the selectivity of sensing with these sensors.

Improved ethanol, acetone and H2 sensing performances of micro-sensors based on loose ZnO nanofibers

“…Adding this pore-forming material in the electrospinning precursor, the nanofibers can turn to loose. The sensing enhancement from this loose morphology can be explained by two aspects [14,15]. Firstly, this morphology is useful to gas adsorption because more active sites are provided on the surface of the ZnO nanofibers, which is a vital factor for high sensitivity.…”

Room temperature H2S micro-sensors with anti-humidity properties fabricated from NiO-In2O3 composite nanofibers

“…Over a period of four decades, metal oxide semiconductor (such as SnO 2 , ZnO, In 2 O 3 and TiO 2 ) based sensors have been under extensive investigation due to their applications in industrial and domestic sectors [1][2][3][4][5]. Semiconductor sensors work on the change of resistance to detect target gases.…”