ZnFe₂O₄ Nanoparticles on ZIF-8-Derived\nZnO for Enhanced Acetone Sensing

Abstract

The development of uniform heterostructures\nfor gas-sensing materials\nis promising to achieve both a fast response and recovery time at\nlow gas levels and good selectivity at significantly high interference\ngas levels. Here we report the preparation of a ZIF-8-derived metal\noxide semiconductor nanocomposite with a heterojunction structure\nand its application as acetone gas sensor. This heterojunction composite\nwas fabricated through <i>in situ</i> growth of ZnFe₂O_<b>4</b> nanoparticles (10–20 nm)\non the outer surface of rhombic dodecahedral-shaped ZnO. Through the\nderivative strategy, the ZnFe₂O₄/ZnO heterojunction\nsensor had a high response value of 225 ± 15 and a fast response\ntime of 6 s to 100 ppm of acetone at the optimum working temperature\nof 260 °C. Furthermore, the response value reached 5.1 for only\n1.8 ppm of acetone even under extremely high humidity (85%). To obtain\na demonstration of the concept, an in-depth investigation of the sensing\nperformances and the microstructure and surface state of ZnO and ZnFe₂O₄/ZnO heterojunction materials was carried out.\nWe found that the excellent acetone sensitivity enhancement could\nlargely be attributed to the ultrahigh number of free electrons and\nthe abundant active sites generated by the tightly bound n–n\nheterojunction structure of ZnFe₂O₄/ZnO and\nthe morphological characteristics. The large specific surface area\nof every sensing domain was the secondary factor in enhancing the\ngas-sensing properties. It suggests that this design for fabricating\nuniform and sensitive gas sensors may facilitate potential applications\nin detecting acetone gas.