Effects of morphologies on acetone-sensing properties of tungsten trioxide nanocrystals

In this work, triclinic WO3 nanoplates and WO3 nanoparticles were comparatively investigated as sensing materials to detect acetone vapors. Single-crystalline WO3 nanoplates with large side-to-thickness ratios were synthesized via a topochemical conversion from tungstate-based inorganic-organic hybrid nanobelts, and the WO3 nanoparticles were obtained by calcining commercial H2WO4 powders at 550 degrees C. The acetone-sensing properties were evaluated by measuring the change in electrical resistance of the WO3 sensors before and after exposure to acetone vapors with various concentrations. The WO3 nanoplate sensors showed a high and stable sensitive response to acetone vapors with a concentration range of 2-1000 ppm, and the sensitivity was up to 42 for 1000 ppm of acetone vapor operating at 300 degrees C. The response and recovery times were as short as 3-10 s and 12-13 s, respectively, for the WO3 nanoplate sensors when operating at 300 degrees C. The acetone-sensing performance of the WO3 nanoplate sensors was more excellent than that of the WO3 nanoparticle sensors under a similar operating condition. The enhancement of the WO3 nanoplate sensors in the acetone-sensing property was attributed to the poriferous textures, single-crystalline microstructures and high surface areas of the aggregates consisting of WO3 nanoplates, which were more favorable in rapid and efficient diffusion of acetone vapors than the WO3 nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.