Facile synthesis of mesoporous ZnO/Co3O4 microspheres with enhanced gas-sensing for ethanol

Self-assembly mesoporous ZnO/Co3O4 microspheres have been successfully synthesized through a facile solvothermal method without any alkali source combined a post-annealing process. The structure, morphology and surface characteristics of the special microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). It was found that the ZnO/Co3O4 microspheres with diameter of about 0.5-1.5 mu m were composed of abundant nanoparticles with an average size of 40 nm. Gas-sensing properties made clear that the response of mesoporous ZnO/Co3O4 microspheres sensors was as high as 38-43 which was about 5 times higher than pure ZnO gas sensors toward 50 ppm ethanol at 275 degrees C. The remarkable improvement in gas-sensing properties of the porous ZnO/Co3O4 microspheres was attributed to their unique mesoporous structure and the extension of the electron depletion layer via the formation of p-n heterojunctions. (C) 2015 Elsevier B.V. All rights reserved.