Electrodeposited tungsten oxide films onto porous silicon for NO2 detection at room temperature

Here we prepare a composite of tungsten oxide films/porous silicon (WO3/PS) hybrid structure synthesized by electrochemical deposition of WO3 films onto p-type PS with subsequent annealing process in air. The obtained WO3/PS products were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy (RS). The gas-sensing properties of WO3/PS composite to NO2 ranging from room temperature (RT, similar to 25 degrees C) to 200 degrees C were studied. The result indicated that all the WO3/PS gas sensors showed typical p-type semiconductor behavior and had an optimal working temperature of RT. Furthermore, compared with PS, the proper deposited WO3/PS composite exhibited a higher gas response, shorter response-recovery time, good repeatability and selectivity toward NO2 gas at RT. This improvement probably owing to the heterojunction effect and its unique microstructure properties. In addition, the possible NO2-sensing mechanisms were also discussed in this paper. (C) 2017 Elsevier B.V. All rights reserved.