Highly toluene sensing performance based on monodispersed Cr2O3 porous microspheres

Monodispersed chromium oxide (Cr2O3) precursor microspheres have been synthesized by an ethanol solvothermal process without using a template or surfactant. Porous Cr2O3 microspheres consisting of nanoparticles have been obtained from a thermal treatment of the precursor microspheres in air. Compositions of the precursor microspheres and the porous microspheres have been characterized by XRD, IR, TG-DTA and XPS; structures of the porous microspheres have been investigated in detail by SEM, TEM, HRTEM and N-2 adsorption-desorption; the structure analysis ascertains that the porous microspheres with diameters of 1.0-1.2 mu m are constructed from nanoparticles with sizes of 40-70 nm. Aggregation of the nanoparticles results in the formation of pores with sizes of 20-80 nm in the microspheres. Thick film sensors, made from these porous Cr2O3 microspheres, exhibit excellent toluene sensing performance with a detection limit of 1 ppm at 170 degrees C. (C) 2012 Elsevier B.V. All rights reserved.