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

Tin oxide (SnO 2 ) nanowires (NWs) and indium oxide (In 2 O 3 ) 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 SnO 2 –In 2 O 3 core–shell nanobelts (NBs). Very few nanomaterial sensors show both strong response (response time + recovery time) and short sensing time. In contrast, the In 2 O 3 -decorated SnO 2 NW sensor fabricated in this study showed both strong response to NO 2 and fast sensing speed or short sensing time. The In 2 O 3 NP-decorated SnO 2 NWs showed stronger and faster response to NO 2 than their pristine SnO 2 counterpart and the SnO 2 –In 2 O 3 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 In 2 O 3 NP-decorated SnO 2 NWs to nitrous oxide (NO 2 ).