P2NG.3 - Highly Selective and Sensitive Detection of Xylene using Cr2O3-ZnCr2O4 Nano-heterostructures

17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
Vienna, Austria
P-2 - Nanomaterials for Gas Sensing
J. Kim, H. Jeong, J. Yoon, J. Lee - Korea University, Seoul (South Korea), C. Na - Korea Institute of Industrial Technology, Busan (South Korea)
850 - 850


The galvanic replacement reaction can be a promising synthetic method for preparing uniform and intimately mixed hetero-nanostructures. In this study, ZnO hollow spheres were synthesized by ultrasonic spray pyrolysis and subsequently converted into Cr2O3/ZnCr2O4 nanocomposite powders or phase-pure ZnCr2O4 powders via galvanic replacement reaction. Single-phase ZnO and Cr2O3 powders showed ethanol selectivity, whereas single-phase ZnCr2O4 showed no substantial response and selectivity to any specific gases. In contrast, the Cr2O3/ZnCr2O4 hetero-nanostructures showed significantly higher response to xylene than other interference gases. For example, the response to 5 ppm xylene is 69.2 at 275 °C which is 26.7 times higher than the response to 5 ppm ethanol. This result demonstrates that co-existence of Cr2O3 and ZnCr2O4 is needed for selective sensing of xylene. To investigate the effect of galvanic replacement reaction, coarse Cr2O3/ZnCr2O4 nanocomposite was prepared by solid state reaction. The sample showed relatively low response and selectivity to xylene. These results suggest that uniformly and intimately mixed Cr2O3 and ZnCr2O4 nano particles exhibit highly selective and sensitive sensing of xylene due to synergistic catalytic promotion and high chemiresistive variation of nanoparticles. The galvanic replacement reaction is a facile and effective synthetic route for preparing oxide hetero-nanostructures for high-performance gas sensor applications.