Nanoscale Heterostructures Based on Fe₂O₃@WO_3-x Nanoneedles and Their Direct Integration into Flexible Transducing Platforms for Toluene Sensing

Abstract

Nanoscale heterostructures based on WO3-x nanoneedles functionalized with Fe2O3 nanoparticles are integrated directly into flexible polymer-based transducing platforms via aerosol-assisted chemical vapor deposition. Results demonstrate that the incorporation of Fe2O3 nanoparticles at the surface of WO3-x nanoneedles enhances the electronic and sensing properties of WO3-x, providing a 6-fold increase in sensitivity to toluene and low cross-sensitivity to hydrogen and ethanol. These enhanced-sensing properties are comparable to those obtained via functionalization with precious metal (Pt) nanoparticles, which are commonly used to enhance sensor performance.

High-Performance Ammonia Sensor at Room Temperature Based on a Love-Wave Device with Fe2O3@WO3−x Nanoneedles

“…Further, analysis of these structures by EDX and HRTEM confirmed the presence of ferric oxide nanoparticles (4-15 nm) dispersed along the tungsten oxide nanoneedles, which is consistent with our previous results for the deposition of Fe2O3@WO3−x nanoneedles on polymer substrates [3]. …”

“…Tungsten oxide has been extensively studied as sensitive layer for gases due to its high capacity to detect different analytes, such as NO2 [2]. In recent years tungsten oxide has been nanostructured as nanoneedles and functionalized with second-phase nanoparticles (e.g., Fe2O3) to increase the gas sensitivity and selectivity to gases such as toluene, hydrogen or ethanol [3]. Our previous works, recently, have also showed the possibility to Love-wave sensors to detect gaseous molecules by elastic properties [4].…”

Understanding the Potential of WO3 Based Sensors for Breath Analysis

“…This would be over 56 ppm if toluene concentrations over the OSHA limit are present. Sensors based on differently modified WO 3 samples are reported to show good signals to toluene within the relevant concentration range [26,27], see Table 7. For example, Miao et al report that the sensors based on anisotropic WO 3 ·H 2 O nanoplatelets operated at 300 °C show high signals to toluene (between 10 and 100 ppm) [26].…”

Gas Sensing Characterization of Single-Nanowire Sensor Array Systems Based on Non-Functionalized and Pt-Functionalized Tungsten Oxide

“…Figure 1 displays a view of the system array ( Figure 1a) and a single nanowire connected across a couple of electrodes (Figure 1b). Previous analysis of the nanowires using STEM and XPS proved the synthesis of non-functionalized and Pt-functionalized tungsten oxide nanowires with diameters between 50 nm and 100 nm, and the incorporation of well dispersed Pt nanoparticles with diameters between 1 nm and 5 nm along the functionalized wires [6]. Gas sensing tests of the nanosensors were carried out at 250 °C using a current of 50 nA.…”