Topochemical Preparation of WO3 Nanoplates through Precursor H2WO4 and Their Gas-Sensing Performances

Size- and shape-controllable preparation of WO 3 nanoplates has been successfully realized through topochemical transformation of corresponding H 2 WO 4 precursors synthesized by a facile solution-phase method. The fluoroboric acid was found to not only provide acid source but also act as a structure-directing agent during the growth process of H 2 WO 4 nanoplates in the solution phase. WO 3 nanoplates could be obtained by the two different topochemical transformation methods, hydrothermal treatment of H 2 WO 4 nanoplates at the temperature (above 160 °C) and calcination at higher temperatures in air, based on their similarity of the W–O octahedral layers in both H 2 WO 4 and WO 3 . Furthermore, the enhanced ethanol-sensing performance could be attributed to the plate-like morphology, especially the high crystallinity, due to the advantages of the effective adsorption and rapid diffusion of the ethanol molecules.