Enhanced NO2 gas sensing performance of the In2O3-decorated SnO2 nanowire sensor

Tin oxide (SnO2) nanowires (NWs) and indium oxide (In2O3) nanoparticles (NPs) were synthesized using thermal evaporation and sol-gel methods, respectively. The NWs were decorated with the NPs by ultraviolet light irradiation and furnace annealing. The sensing properties of the NP-decorated NWs were compared with those of SnO2-In2O3 core-shell nanobelts (NBs). Very few nanomaterial sensors show both strong response (response time + recovery time) and short sensing time. In contrast, the In2O3-decorated SnO2 NW sensor fabricated in this study showed both strong response to NO2 and fast sensing speed or short sensing time. The In2O3 NP-decorated SnO2 NWs showed stronger and faster response to NO2 than their pristine SnO2 counterpart and the SnO2-In2O3 core-shell nanobelts. The experimental results also confirmed the importance of heterostructure formation and operating temperature optimization of the sensing variables, such as temperature, gas concentration, and the type of gas on the sensor response. The sensor response was strongly dependent on the type of gas. The gas sensing mechanism of the nanostructures for each sensing variable was discussed in detail. In addition, repeated sensing measurement highlighted the reversibility and reproducibility of the response of the In2O3 NP-decorated SnO2 NWs to nitrous oxide (NO2).