Synthesis of ZnO@ZIF-8 Nanorods with Enhanced Response to VOCs

Abstract

It is an effective way to produce core–shell composite materials by coating nano-metal oxides with metal-organic framework. A self-sacrificial method was reported. ZnO was transformed into ZIF-8 and attached to ZnO. Through the in situ transformation of zinc oxide particles in the matrix, a great many pores are formed to ensure that all parts of ZnO can contact the gas. ZnO has three main functions, providing Zn 2+ for ZIF-8 and serving as a template for ZIF-8’s growth, and as an active material to detect gases. ZIF-8 has two functions. Firstly, it has hydrophobicity to avoid the impact of steam on the gas detection of ZnO; secondly, it can provide a large amount of pores, increase the specific surface area. A great many defects created at the interface of the two materials increases the active sites. The gas-sensing performance of ZnO to volatile organic compounds can be improved using the advantages of both materials. The composite sensor has an optimal operating temperature of 350 °C and has more than tripled its response to 50 ppm gases relative to the ZnO sensor. In addition, a gas-sensing mechanism is proposed. An effective strategy for developing high-response VOC sensors is presented in this work.