Porous NiO-WO3 heterojunction nanofibers fabricated by electrospinning with enhanced gas sensing properties

A series of NiO-WO3 composite nanofibers with different molar ratios (Ni/W- 0%, 1%, 3% and 5%) were fabricated based on an electrospinning and calcination technique. The gas sensing performances of sensors based on the as-produced nanofibers were studied towards acetone in detail. Compared with the pure WO3 nanofibers, the porous NiO-WO3 composite nanofibers exhibited higher sensitivity, faster response, and shorter recovery time towards acetone. Particularly, the 3 mol% NiO-WO3 heterojunction nanofibers demonstrated the largest sensitivity, exhibiting a prominent value of 22.5 under 100 ppm acetone at the operating temperature of 375 degrees C, which is almost 2.1 times larger than that of the pure WO3 nanofibers. Moreover, the 3 mol% NiO-WO3 heterojunction nanofibers also exhibited excellent selectivity and long-term stability to acetone. The combined effects including the formation of p-n heterojunctions between NiO and WO3, high oxygen species absorbing capacity, and special porous structural features with high surface area and small grain size, contributed to the enhanced sensing properties of the 3 mol% NiO-WO3 composite nanofibers. These attractive gas sensing properties enable the NiO-WO3 heterojunction nanofibers to be a promising material for application in gas sensors.