Impact of Microwave Irradiation on the NO2 Gas Sensing Properties of ZnO Nanoparticles

초록

This study explores the influence of microwave (MW) irradiation time on the NO2 gas sensingperformance of ZnO nanoparticles (NPs). ZnO NPs were subjected to MW irradiation for 1, 3, 5, and 7 minutesto assess the effects of defect engineering via MW irradiation on their sensing behavior. Phase andmorphological characterizations using XRD and SEM confirmed that MW irradiation did not inducesignificant changes in the crystalline phase or surface morphology of the ZnO NPs. However, PL, XPS, TEM,and EDS results revealed the generation of defects, which were particularly pronounced after five minutesof MW exposure. The pristine ZnO NPs sensor displayed a response of 6.0 to 2 ppm NO2 at 250 °C. After fiveminutes of MW irradiation, the response nearly doubled to 11.25 under the same conditions and reached 34.63at 10 ppm NO2. The improved sensitivity was attributed to the formation of defect sites, ZnO-ZnOhomojunctions, and ZnO-Zn(OH)2 heterojunctions. Notably, the sensor irradiated for five minutes alsodemonstrated excellent selectivity toward NO2 in the presence of interfering gases. These results demonstratethat MW-assisted defect modulation is a promising and scalable strategy to boost sensing features of ZnO NPs. It is anticipated that high-efficiency sensors tailored for specific environmental and industrial applicationscould be developed with further optimization of MW parameters and integration with surface modificationtechniques.

키워드