UV-enhanced gas sensing properties of Bi2O3 nanorods encapsulated with ZnO at room temperature

초록

Bi2O3 is highly sensitive to low concentrations of NO2 in ambient air and are almost insensitive to most other common gases. However, it still remains a challenge to enhance their sensing performance and detection limit. This study examined the influence of the encapsulating Bi2O3 nanorods with ZnO on the NO2 gas sensing properties. ZnO-encapsulated β-Bi2O3 nanorods were fabricated by the thermal evaporation of Bi2O3 powder followed by atomic layer deposition of ZnO. The room temperature NO2 gas sensing properties of the nanorods under ultraviolet (UV) illumination were examined. The cores and shells of the nanorods were primitive tetragonal-structured single crystal Bi2O3 and wurtzite-structured single crystal ZnO, respectively. The responses of multiple networked Bi2O3 nanorod sensors were increased 2-3 fold at NO2 concentrations ranging from 1 to 5 ppm by encapsulating the nanorods with ZnO. The Bi2O3-core/ZnO-shell nanorod sensors showed a remarkably enhanced response under UV illumination. The sensing mechanism of the core-shell nanorods under UV illumination is also discussed.