Fabrication of ZIF-8 encapsulated ZnO microrods with enhanced sensing properties for H2 detection

Abstract

As one of the most typical fault characteristic gases in transformer oil, the content of H2 is an important criterion for judging the operation state of power transformers; while online monitoring of such species through gas sensing technology could effectively detect latent faults and avoid accidents. Zinc oxide is a popular sensing material in recent years with limited sensitivity, selectivity and stability for gas detection, while zeolite imidazolate framework-8 (ZIF-8), one kind of metal–organic frameworks (MOFs) materials, possesses adjustable porosity, huge specific surface areas and good thermal stability, so it could perfectly remedy those defects. This paper studied gas-sensing properties of ZnO rods encapsulated by ZIF-8 (ZnO@ZIF-8) for H2. The morphologies, structures, and composition were characterized in detail by means of X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and energy disperse spectroscopy. H2 gas sensing properties of pure ZnO and ZnO@ZIF-8 composites were implemented based on gas sensing platform. Results suggested that the ZnO@ZIF-8 showed better sensitivity, selectivity and stability than pure ZnO rods, and meanwhile possessed lower optimum operating temperature upon H2 detection. Meanwhile the gas-sensing mechanism was analyzed comprehensively from three aspects of sensitivity, selectivity and stability. Our aim of this work is to propose a novel core–shell material with enhanced performance for H2 sensing and provide a new idea for developing high-performance materials to detect fault characteristic gases.