Enhanced CO sensing characteristics of hierarchical and hollow In2O3 microspheres

Hierarchical and hollow In2O3 miciospheres were prepared by a solvothemal self-assembly reaction and their CO sensing characteristics were compared to those of an agglomerated counterpart. Upon exposure to 10-50 ppm CO at 400 degrees C, the gas responses (R-a/R-g; R-a: resistance in air, R-g: resistance in gas) of the hierarchical and hollow Structures were 1.6-2.7 times higher than that of the agglomerated sample. In addition, their 90% responses and recovery speeds were 23 times and 7.7 times higher, respectively. Their significantly improved gas responses and sensing/recovery kinetics were concluded to be Mated to the nanoporous and well-aligned nanostructures, which allow effective and rapid gas diffusion toward the sensing surfaces. (C) 2009 Elseviei B.V. All rights reserved.