Metal-organic framework-derived highly dispersed Pt nanoparticles-functionalized ZnO polyhedrons for ppb-level CO detection

Abstract

Abstract Metal oxides-based CO sensors with ppb-level detection limit are highly desirable in the application of air quality monitoring and exhaled breath detection. Synthesis of porous nanostructure unit with a large number of active sites has been deemed as an effective way to lower the detection limit of metal oxides-based sensors. This work reports a regular approach for the synthesis of highly dispersed Pt nanoparticles-functionalized ZnO polyhedrons (Pt NPs@ZnO) using metal-organic framework (ZIF-8) as a template. Nanoscale Pt NPs with a narrow size distribution (2−5 nm) were in-situ loaded on the cavities of porous ZnO. The prepared Pt NPs@ZnO polyhedrons exhibited good CO response ((Ra-Rg)/Ra·100 % = 9%–500 ppb), long-term stability, ultra-low detection limit (100 ppb) and superior CO selectivity. To the best of our knowledge, the detection limit toward CO reported in this work is the lowest experimental value among those metal oxide-based sensors reported so far. The enhanced CO sensing properties are owing to the porous nanostructures, high specific surface area, the catalytic effects and electron sensitization effects of highly dispersed Pt NPs. The Pt NPs@ZnO sensor has a great potential application for detecting low-concentration CO.