ZnFe2O4/ZnO nanosheets assembled microspheres for high performance trimethylamine gas sensing

ZnFe2O4/ZnO nanosheets assembled microspheres (ZnFe2O4/ZnO SAS) were successfully constructed by hydrothermal synthesis of ZnO nanosheets assembled microsphere and subsequent growth of ZnFe2O4 nanoparticles on it via a facile solution method. The morphologies and components of as-synthesized ZnFe2O4/ZnO SAS composites were varied with growth time, and ZnFe2O4/ZnO SAS composite with the growth time of 30 min (ZnFe2O4/ZnO SAS30) consisted of porous nanosheets assembled by small ZnFe2O4 and ZnO nanoparticles. The composites were applied as sensing film for trimethylamine (TMA) sensing. ZnFe2O4/ZnO SAS30 based sensor exhibited good selectivity and higher response to TMA than that of sensors based on bare ZnO microspheres precursor, ZnO/ZnFe2O4 nanoparticle composite and other ZnFe2O4/ZnO SAS composites, respectively. At 240 °C, the ZnFe2O4/ZnO SAS30 based sensor exhibited 31.5–100 ppm TMA with a quick response and recovery time of 3.1 s and 5.7 s, respectively, and even as low as 0.1 ppm TMA can be detected. Meanwhile, the corresponding cycling performance and stability was also checked. Such favorable comprehensive sensing performance of ZnFe2O4/ZnO SAS30 to TMA was attributed to its unique hierarchical structure and ZnO/ZnFe2O4 heterojunctions. All results enabled potential applications of ZnFe2O4/ZnO SAS30 composite in TMA sensing. •ZnFe2O4/ZnO composites with novel hierarchical and heterojuctional structure were synthesized.•The growth time of ZnFe2O4 was varied to optimum the composite sensing properties.•ZnFe2O4/ZnO composite sensors showed high trimethylamine sensing performance.