WO3 porous nanosheet arrays with enhanced sensing performance low temperature NO2 gas

WO3 porous nanosheet arrays have been prepared by a facile chemical bath deposition. The as-prepared nanosheet arrays are found to be precursors of tungstite and hydrotungstite. The nanosheets become porous upon annealing of the precursors due to the removal of crystalline water. Constructed from porous nanosheets with ultra-thin thickness of 20 nm, WO3 arrays exhibit enhanced low temperature NO2 gas sensing performance. A high response of 460 toward 10 ppm NO2 is achieved at a working temperature of 100 degrees C. The superior sensing performance of the WO3 porous nanosheet arrays compared to the thick WO3 layer is ascribed to the high degree of participation in surface reaction with the gas for the nanosheet arrays. The temperature-dependant gas response to NO2 is interpreted by the competitive adsorption of oxygen and NO2 at low temperature and their desorption at high temperature.