Low-temperature and highly selective NO-sensing performance of WO3 nanoplates decorated with silver nanoparticles

For improving the low-temperature response and selectivity of WO3-based sensors, Ag nanoparticles (AgNPs) have been used to modify the WO3 nanoplates. Ag@plate-WO3 nanocomposites with various amounts of AgNPs were synthesized by growing AgNPs on WO3 nanoplates. XRD, SEM, TEM and XPS spectrum were used to characterize the Ag@plate-WO3 samples. The gas-sensing properties were evaluated at r.t. -250 degrees C using NO gases with various concentrations (0.5-50 ppm). AgNPs enhance the low-temperature response and selectivity of the Ag@plate-WO3 sensors for NO detection, and the amounts of AgNPs influence the NO-sensing performance of the Ag@plate-WO3 sensors. The sample with 0.5% AgNPs shows the best performance. Its optimum operating temperature is around 170 degrees C, but it shows response even at room temperature. The Ag@plate-WO3 sensors have a high selective response to NO gas, among various gases (i.e., H-2 and CO) and organic vapors (i.e., alcohol, acetone, methanol and benzene). The morphologies of WO3 nanocrystals also influence the NO-sensing properties of the Ag@WO3 sensors, and the plate-like WO3 samples are better than the particle-like WO3 samples in improving NO-sensing performance. The NO-sensing enhancement should result from the synergistic effects of AgNPs and the loose house-of-card structure of plate-like WO3 aggregates. (C) 2013 Elsevier B.V. All rights reserved.