Enhanced selective response to nitric oxide (NO) of Au-modified tungsten trioxide nanoplates

Au-modified WO3 nanoplates (Au@plate-WO3) were synthesized by chemically reducing HAuCl4 on the surfaces of two-dimensional WO3 nanoplates, which were derived from an intercalation–topochemical process. XRD, SEM, TEM, XPS and UV–vis DR spectra were used to characterize the WO3 nanoplates and Au@plate-WO3 nanocomposites. The gas-sensing properties of the WO3 nanoplates and Au@plate-WO3 nanocomposites were comparatively investigated using inorganic gases and organic vapors as the target gases, with an emphasis on exploring the response and selectivity of NO gases with low concentrations (0.5–10 ppm) at low operating temperature (130−250 °C). The results indicated that Au nanoparticles (Au NPs) enhance the low-temperature sensitivity and selectivity of the Au@plate-WO3 sensors for NO detection when compared with the performance of the WO3 sensors. The Au@plate-WO3 nanocomposite with 1 wt.% Au NPs has the best NO-sensing performance at the optimum operating temperature of ∼170 °C. In addition, the Au@plate-WO3 sensors show highly selective to NO gas among various inorganic gases (i.e., H2, SO2 and CO) and organic vapors (i.e., alcohol, acetone, methanal and benzene). The enhancement in sensitivity and selectivity for NO detection is probably due to the synergistic effect of Au NPs and the house-of-card structure of WO3 nanoplates.