Biopolymer-assisted construction of porous SnO2 microspheres with enhanced sensing properties

Abstract

Nanoparticle-assembled SnO2 microspheres with a porous structure are prepared by a biopolymer-assisted synthetic method. The biopolymer used herein is sodium alginate. Besides sodium alginate, an ethylene glycol–water mixed solvent system is also proven to be necessary for the formation of the porous SnO2 microspheres. The gas-sensing properties of this material are evaluated by a range of gases, and the results show that the gas sensor based on the porous SnO2 material exhibits the highest sensing response towards ethanol relative to other testing gases. The sensing response of the porous SnO2 is ∼3 and 4 times as high as those of the solid SnO2 microspheres (which are prepared in the absence of sodium alginate) and the commercially available SnO2 nanoparticles, respectively. In addition, the porous SnO2 sensor exhibits a wide response range from 0.5 to 200ppm for ethanol detection. In the testing range from 0.5 to 200ppm, the logarithm of the response value shows a good linear dependency on the logarithm of ethanol concentration, indicating that the porous SnO2 sensor may be used for quantitative detection of ethanol vapor.