Hierarchical In₂O₃@SnO₂ Core–Shell Nanofiber for High Efficiency Formaldehyde Detection

Abstract

In this work, three-dimensional (3D) hierarchical In2O3@SnO2 core–shell nanofiber (In2O3@SnO2) was designed and successfully prepared via a facile electrospinning and further hydrothermal methods. Vertically aligned SnO2 nanosheets uniformly grown on the outside surface of In2O3 nanofibers were clearly observed by field emission scanning electron microscopy. Besides, hierarchical core–shell nanostructure of In2O3@SnO2 was characterized by elemental maps using scanning transmission electron microscopy. The formaldehyde (HCHO) sensing performances of pure In2O3 nanofibers, SnO2 nanosheets, and In2O3@SnO2 core–shell nanocomposite were compared, and the In2O3@SnO2 nanocomposite possessed highest response value, fast response/recovery speed, best selectivity, and lowest HCHO detection limit. Specifically, the response value (R a/R g) of the In2O3@SnO2 nanocomposite reached 180.1 toward 100 ppm of HCHO gas, which was near 9 and 6 times higher than that of the pure In2O3 nanofibers (R a/R g = 19.7) and pure SnO2 nanosheets (R a/R g = 33.2), respectively. In addition, the gas sensor showed instantaneous response/recovery time (3/3.6 s) toward 100 ppm of HCHO at the optimal operation temperature of 120 °C. More importantly, the detection limit toward HCHO gas was as low as 10 ppb (R a/R g = 1.9), which could be used for trace HCHO gas detection. The excellent sensing properties of the In2O3@SnO2 were attributed to the synergistic effect of large specific surface areas of SnO2 nanosheet arrays, abundant adsorbed oxygen species on the surface, unique electron transformation between core–shell heterogeneous materials, and long electronic transmission channel of SnO2 transition layer. This work provides an efficient route for the preparation of novel hierarchical sensitive materials.

Sensitive Cross-Linked SnO2:NiO Networks for MEMS Compatible Ethanol Gas Sensors

“…It can be concluded that a low detection limit of < 5 ppm can be achieved for our network based sensors. However, the measured response and recovery time of network sensor are in the order of minutes, much longer than the nanomaterial-based sensors [53,54]. Compared with the test system and sensing materials in the reported sensors, we believe that the long response and recovery time in our work can be attributed to the following two reasons.…”

Construction of ZnTiO3/Bi4NbO8Cl heterojunction with enhanced photocatalytic performance

“…The crystal structure of the samples could be detected from XRD results [20], as shown in Fig. 1a Figure 1b shows that ZnTiO 3 sample is micron-scale irregular blocks structure.…”

Design and Synthesis of Nanostructured Materials for Sensor Applications

“…Another study reports a 3D hierarchical In 2 O 3 @SnO 2 coreshell nanofiber (In 2 O 3 @SnO 2 ) designed using vertically aligned SnO 2 nanosheets uniformly grown on the outside surface of In 2 O 3 nanofibers and tested for the sensing performance of formaldehyde (HCHO) [121]. The sensing performance of the In 2 O 3 @SnO 2 nanocomposite was found to possess the highest response value, fast response/recovery speed, best selectivity, and lowest HCHO detection limit which were attributed to the synergistic effect of large specific surface areas of SnO 2 nanosheet arrays, abundant adsorbed oxygen species on the surface, unique electron transformation between core-shell heterogeneous materials, and long electronic transmission channel of SnO 2 transition layer [121].…”