Metal-organic gel derived ZnO/α-Fe2O3 heterostructures for sensitive NO2 detection

Fabrication of metal oxide semiconductor heterostructures is an important means to improve sensor performance. However, the design of efficient heterostructures to reduce the operating temperature of metal oxides and obtain high sensitivity and selectivity remains a challenge. In this work, ZnO/alpha-Fe2O3 heterostructures were prepared by pyrolysis of Fe-based organic gel on ZnO nanorods, and their NO2 sensing properties were systematically studied. The alpha-Fe2O3 nanoparticles transformed from Fe-organic gel are evenly dispersed on the surface of ZnO nanorods, endowing the materials with a large specific surface area and remarkable charge modulation at the ZnO/alpha-Fe2O3 interface. The ZnO/alpha-Fe2O3 sensor shows superior selectivity and repeatability for NO2 detection at 175 degrees C, as well as short response-recovery time (24/32 s), low detection limit (79 ppb) and reliable stability. This study provides a useful strategy for the construction of core-shell heterostructure sensing materials.