▎ 摘　　要

Here, we have newly developed chemically functionalized three-dimension (3D) graphene oxide hydrogels (FGH) decorated with metal-organic frameworks (MOFs)-derived Co3O4 nanostructures, in which the Co3O4 nanostructures are uniformly distributed in 3D FGH frameworks. It is found that the Co3O4/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 similar to 20 times higher than that of pristine Co3O4 film, a short response time (similar to 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 Co3O4/FGH can be mainly attributed to the unique porous structures of 3D FGH frameworks and the modulation of electrical transport properties of the Co3O4/FGH junctions in the composites. The Co3O4 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 Co3O4/FGH junctions so that the resistance of Co3O4/FGH composites is greatly increased. Therefore, the acetone response of the composites is dramatically enhanced because of the Co3O4/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. (c) 2017 Elsevier B.V. All rights reserved.