Construction of In2O3/ZnO yolk-shell nanofibers for room-temperature NO2 detection under UV illumination

Room-temperature gas sensors have emerged as effective platforms for sensing explosive or toxic gases in ambient environment. However, room-temperature gas sensor usually suffers from extremely poor sensitivity and sluggish response/recovery characteristics due to the low reacting activity at low temperature. Herein, we present a room-temperature NO2 sensor with greatly enhanced sensitivity and rapid response/recovery speed under ultraviolet (UV) illumination. The sensor based on In2O3/ZnO yolk-shell nanofibers exhibits remarkable sensitivity (Rg/Ra = 6.0) to 1 ppm NO2 and rapid response/recovery time (≤36, 68 s) under UV illumination, obviously better than negligible sensing performance and inefficient response/recovery properties in dark condition. Such excellent gas sensing properties of the In2O3/ZnO yolk-shell nanofibers were not only attributed to the improved photo-generated charge separation efficiency derived from the effect of heterojunction, but also related to the enhanced receptor function towards NO2 endowed by increased reactive sites and gas adsorption. These proposed strategies will provide a reference for developing high-performance room-temperature gas sensors.