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Synergistic Effects of a Combination of Cr2O3-Functionalization and UV-Irradiation Techniques on the Ethanol Gas Sensing Performance of ZnO Nanorod Gas Sensors
- Park, Sunghoon, Sun, Gun-Joo, Jin, Changhyun, Kim, Hyoun
Woo, Lee, Sangmin, Lee, Chongmu
- ACS applied materials 2016 v.8 no.4 pp. 2805-2811
- adsorption, ambient temperature, ethanol, evaporation, graphene, nanoparticles, nanorods, oxidation, powders, ultraviolet radiation, zinc oxide
- There have been very few studies on the effects of combining two or more techniques on the sensing performance of nanostructured sensors. Cr₂O₃-functionalized ZnO nanorods were synthesized using carbothermal synthesis involving the thermal evaporation of a mixture of ZnO and graphite powders followed by a solvothermal process for Cr₂O₃-functionalization. The ethanol gas-sensing properties of multinetworked pristine and Cr₂O₃-functionalized ZnO nanorod sensors under UV illumination were examined to determine the effects of combining Cr₂O₃–ZnO heterostructure formation and UV irradiation on the gas-sensing properties of ZnO nanorods. The responses of the pristine and Cr₂O₃-functionalized ZnO nanorod sensors to 200 ppm of ethanol at room temperature by UV illumination at 2.2 mW/cm² were increased by 3.8 and 7.7 times, respectively. The Cr₂O₃-functionalized ZnO nanorod sensor also showed faster response/recovery and better selectivity than those of the pristine ZnO nanorod sensor at the same ethanol concentration. This result suggests that a combination heterostructure formation and UV irradiation had a synergistic effect on the gas-sensing properties of the sensor. The synergistic effect might be attributed to the catalytic activity of Cr₂O₃ for ethanol oxidation as well as to the increased change in conduction channel width accompanying adsorption and desorption of ethanol under UV illumination due to the presence of Cr₂O₃ nanoparticles in the Cr₂O₃-functionalized ZnO nanorod sensor.