Chemically functionalized 3D reticular graphene oxide frameworks decorated with MOF-derived Co3O4: Towards highly sensitive and selective detection to acetone

Here, we have newly developed chemically functionalized three-dimension (3D) graphene oxide hydrogels (FGH) decorated with metal-organic frameworks (MOFs)-derived Co 3 O 4 nanostructures, in which the Co 3 O 4 nanostructures are uniformly distributed in 3D FGH frameworks. It is found that the Co 3 O 4 /FGH composites exhibits excellent acetone sensing properties, for instance, it shows an ultra-high response (R gas /R 0  = 81.2) to 50 ppm acetone, which was ∼20 times higher than that of pristine Co 3 O 4 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 /R 0  = 4.06). The excellent acetone sensing properties of Co 3 O 4 /FGH can be mainly attributed to the unique porous structures of 3D FGH frameworks and the modulation of electrical transport properties of the Co 3 O 4 /FGH junctions in the composites. The Co 3 O 4 nanostructures uniformly distributed in 3D FGH frameworks can easily adsorb a great amount of acetone gas molecules through the unique porous frameworks and produce a great deal of electrons, which can be transferred to the p-type FGH frameworks through Co 3 O 4 /FGH junctions so that the resistance of Co 3 O 4 /FGH composites is greatly increased. Therefore, the acetone response of the composites is dramatically enhanced because of the Co 3 O 4 /FGH junctions. This study presents a new idea of building MOF-derived oxides/FGH junctions to enhance gas response of oxide-based gas sensors, and has great potential in fabrication of new generation gas sensors.