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.
Keywords: 3D hetero-nanofibers; electrospinning; gas sensors; gas-sensing mechanism; heterojunctions.