Preparation And Acetone Sensing Properties Of MOFs Derived Co₃O₄/3D Graphene Composites

With the continuous development of human society,the massive emission of toxic and hazardous gases not only pollutes the atmosphere but also seriously threatens the health of human beings.Therefore,the detection of toxic and hazardous gases plays an extremely important part in monitoring environmental quality and protecting personal safety.Acetone?CH₃COCH₃?,a critical member of volatile organic compounds?VOCs?family,is closely related to human life.On one hand,it is the most commonly used volatile chemical reagents in industry and laboratory.Inhalation of large amounts of acetone may cause the anesthesia of central nervous system.Prolonged exposure to high concentration of acetone may also cause damage to the liver,kidney and pancreas.On the other hand,the acetone concentration is higher in diabetic patients than that in healthy human body,so detecting the concentration of acetone in exhaled breath is also an important reference standard and auxiliary measure for diagnosing diabetics.In this paper,we have newly developed chemically functionalized three-dimension?3D?graphene-based materials?FGOH?decorated with metal-organic frameworks?MOFs??ZIF-67/FGOH?,and then we carried out two different heat-treatment processes to fabricate MOF-derived Co₃O₄ nanostructures and 3D graphene composites?Co₃O₄/FGOH and Co₃O₄/FGH?,in which the Co₃O₄ nanostructures are uniformly distributed in 3D graphene-based frameworks.We systematically studied the acetone sensing performance of the as-prepared samples.It is found that Co₃O₄-A reaches the largest response(R_gas/R₀=2.57@25 ppm acetone,190°C)and Co₃O₄-N reaches the largest response(R_gas/R₀=5.65@25 ppm acetone,160°C).In addition,ZIF-67/FGOH composites were prepared by facile self-assembly method,and then the granular Co₃O₄/FGOH and polyhedral Co₃O₄/FGH composites are obtained by pyrolysis of ZIF-67/FGOH composites with the same annealing process as Co₃O₄-A and Co₃O₄-N,respectively.It is found that Co₃O₄/FGOH composites exhibits excellent acetone sensing properties,for instance,it shows an ultra-high response(R_gas/R₀=81.2@50 ppm acetone,250°C),which was around 20 times higher than that of pristine Co₃O₄-A film,a short response time?²0 s?,and a distinct cross-selectivity against other interfering gases.Notably,upon exposure to 1 ppm acetone in air,the composites still can express an apparent response(R_gas/R₀=4.06).In addtion,it is also found that Co₃O₄/FGH delivers selective detection capability to acetone,high response(R_gas/R₀=58.1@50 ppm acetone,200°C)which was about 7.4 times higher than that of pristine Co₃O₄-N film,and superior cross-selectivity against other interfering gases.This study presents a new idea of building MOF-derived oxides/FGOH junctions to enhance gas sensitivity of oxide-based gas sensors,and has great potential in the fabrication of new generation gas sensors.