ZnO/ $\gamma$ -Fe2O3 Heterostructure Toward High-Performance Acetone Sensing

A novel hierarchical heterostructure based on ZnO/γ-Fe₂O₃ nanorods decorated with nanoparticles has been synthesized via simple solvothermal approach followed by calcination at an elevated temperature. Considering the unique properties of both ZnO and γ-Fe₂O₃ toward the sensing of reducing gases, the concept of forming a heterostructure between them has been conceived. The crystallinity, morphological structure, and defect states of nanostructures based on ZnO/γ-Fe₂O₃ composites were investigated by XRD, FESEM, TEM, and PL spectroscopy analysis. A flowerlike morphology was revealed with the coexistence of both ZnO and γ-Fe₂O₃ leading to the formation of the heterostructure. The as-prepared ZnO/γ-Fe₂O₃ sensors display apparently enhanced sensing characteristics, including higher sensing response, quick response with recovery, and better selectivity toward acetone gas as compared to bare ZnO nanorods. The sensor showed selective detection of acetone among six VOC's at an optimum temperature of 300°C. The response and recovery time of the sensor was found to be 12.5 and 26.9 s, respectively, compared to 51 and 80 s for bare ZnO nanorods, when exposed to 60-ppm concentration of acetone. This ultrafast and selective detection of acetone by ZnO/γ-Fe₂O₃ heterostructure shows potential to develop future commercial acetone sensor.