Sensing performance of palladium-functionalized WO3 nanowires by a drop-casting method

Abstract

In this work, we show a simple way to functionalize tungsten oxide nanowires (WO3-NWs) using a saturated palladium chloride (PdCl2) solution deposited by a drop-casting method. WO3-NWs were synthesized by close-spaced chemical vapor deposition (CSVT). The morphological and structural characterizations showed that the diameters of WO3-NWs are in the range from 50 to 200nm with lengths above 10μm, and correspond to the orthorhombic phase of WO3, respectively. The sensor was fabricated using the WO3-NWs and tested with hydrogen and volatile organic compounds (VCO's). A comparative study was done on the sensing performance, before and after the Palladium functionalization of the WO3-NWs, considering a wide range of gas concentrations and moderate operating temperatures (100–400°C). The results show that this simple functionalization process significantly increases the sensor sensitivity and reduces the time constants. In addition, it has been shown that at 300°C the decorated sensor becomes more selective to hydrogen and xylene for all concentrations considered in this research. Finally, the mechanisms involved in improving the gas sensing properties of WO3-NWs functionalized with Palladium are discussed.