Surface functionalization of porous In₂O₃ nanofibers with Zn nanoparticles for enhanced low-temperature NO₂ sensing properties

Different from the dominant method of surface modification of metal oxide sensing materials with noble metals, a simple and low-cost method is developed by using Zn nanoparticles as a surface modifier in this work. The first step involves the fabrication of porous In₂O₃ nanofibers by an electrospinning technique, and then Zn nanoparticles decorated In₂O₃ nanofibers are constructed by a simple thermal evaporation method. An increase in surface species absorbing capability and a decrease in sensor resistance are observed by surface modification of In₂O₃ nanofibers with Zn nanoparticles. In comparison with pure In₂O₃ nanofibers, this kind of Zn–In₂O₃ composite nanofibers display higher response and better selectivity to NO₂. The response of Zn–In₂O₃ nanofibers is up to 130.00–5 ppm NO₂ at 50 °C, which is 13.7 times higher than that of pure In₂O₃. From our perspective, the improved NO₂ sensing performances of Zn–In₂O₃ composite nanofibers are mainly attributed to the enhanced resistance modulation because of the formation of ohmic contacts between Zn nanoparticles and In₂O₃ nanoparticles.