Zinc Oxide Coated Tin Oxide Nanofibers for Improved Selective Acetone Sensing

Abstract

Three-dimensional hierarchical SnO2/ZnO hetero-nanofibers were fabricated by the electrospinning method followed with a low-temperature water bath treatment. These hierarchical hollow SnO2 nanofibers were assembled by the SnO2 nanoparticles through the electrospinning process and then the ZnO nanorods were grown vertically on the surface of SnO2 nanoparticles, forming the 3D nanostructure. The synthesized hollow SnO2/ZnO heterojunctions nanofibers were further employed to be a gas-sensing material for detection of volatile organic compound (VOC) species such as acetone vapor, which is proposed as a gas biomarker for diabetes. It shows that the heterojunction nanofibers-based sensor exhibited excellent sensing properties to acetone vapor. The sensor shows a good selectivity to acetone in the interfering gases of ethanol, ammonia, formaldehyde, toluene, and methanol. The enhanced sensing performance may be due to the fact that n-n 3D heterojunctions, existing at the interface between ZnO nanorods and SnO2 particles in the SnO2/ZnO nanocomposites, could prompt significant changes in potential barrier height when exposed to acetone vapor, and gas-sensing mechanisms were analyzed and explained by Schottky barrier changes in SnO2/ZnO 3D hetero-nanofibers.

Exploring SnxTi1−xO2 Solid Solutions Grown onto Graphene Oxide (GO) as Selective Toluene Gas Sensors

“…Nevertheless, also in this case, the operating temperature with the highest response is 350 • C [26]. Moreover, Kim et al [34] reported exceptional toluene sensing properties of novel SnO 2 /ZnO core-shell nanowires, functionalized with Pt nanoparticles, showing an excellent R air /R analyte intensity response to 100 ppb at 300 • C. Remarkably, as sticks out, the majority of the most promising reported sensor materials achieve the best performances only at high operating temperatures, especially above 250-300 • C [26,34].…”

“…For instance, small polar molecules are better detected than volatile hydrocarbons, and similar VOCs still give identical responses [21,22]. However, the latter issue can be partially solved by adopting different approaches, such as (i) the synthesis of 3-dimensional hierarchical, mesoporous or hollow networks with enhanced surface activity [23][24][25]; (ii) the engineering of nano-heterojunctions that prompt significant changes in the potential barrier height upon exposure to different analytes [26][27][28]; (iii) the doping or decoration with noble metal nanoparticles having a diverse catalytic effect towards a specific VOC molecule; and (iv) the statistical elaboration of data obtained by multiple sensor arrays [29,30]. Hence, in this context, scientific research is focusing attention on the preparation of novel materials able to sense VOCs at room temperature, thus reducing the energy consumption, reaching high sensitivity (of ppb concentration) and a good selectivity [31][32][33].…”

“…Hence, in this context, scientific research is focusing attention on the preparation of novel materials able to sense VOCs at room temperature, thus reducing the energy consumption, reaching high sensitivity (of ppb concentration) and a good selectivity [31][32][33]. For instance, Quan et al [23] have recently pointed out the hierarchical flower-like Pt-doped 3D porous SnO 2 possesses excellent selectivity for acetone molecules, showing a good response down to 50 ppb at a relatively high temperature of 153 • C. Besides, 3D hierarchical hollow SnO 2 /ZnO hetero-nanofibers have been described as potential acetone selective sensors thanks to the occurrence of an n-n type junction at the interface between ZnO and SnO 2 , thus resulting in an enhanced electronic transport [26]. Nevertheless, also in this case, the operating temperature with the highest response is 350 • C [26].…”

“…For instance, Quan et al [23] have recently pointed out the hierarchical flower-like Pt-doped 3D porous SnO 2 possesses excellent selectivity for acetone molecules, showing a good response down to 50 ppb at a relatively high temperature of 153 • C. Besides, 3D hierarchical hollow SnO 2 /ZnO hetero-nanofibers have been described as potential acetone selective sensors thanks to the occurrence of an n-n type junction at the interface between ZnO and SnO 2 , thus resulting in an enhanced electronic transport [26]. Nevertheless, also in this case, the operating temperature with the highest response is 350 • C [26]. Moreover, Kim et al [34] reported exceptional toluene sensing properties of novel SnO 2 /ZnO core-shell nanowires, functionalized with Pt nanoparticles, showing an excellent R air /R analyte intensity response to 100 ppb at 300 • C. Remarkably, as sticks out, the majority of the most promising reported sensor materials achieve the best performances only at high operating temperatures, especially above 250-300 • C [26,34].…”

UV Light Activated SnO2/ZnO Nanofibers for Gas Sensing at Room Temperature

“…The SnO 2 /ZnO heterojunction nanofibers were prepared following a two-step process (Mailhiot and Duke, 1986;Du et al, 2018). Firstly, the SnO 2 nanofibers were synthesized by the high-voltage electrospinning method.…”