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 °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 °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 °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.