Enhancement of gas-sensing characteristics of hydrothermally synthesized WO3 nanorods by surface decoration with Pd nanoparticles

Enhancement of the gas-sensing characteristics of nanostructured metal oxides by surface decoration with noble metal nanoparticles has recently received significant attention as a powerful technique for improving gas-sensing performance. Herein, we introduce a facile method of decorating tungsten oxide (WO3) nanorods by palladium (Pd) nanoparticles to achieve enhanced NH3 gas-sensing performance. The WO3 nanorods were synthesized by a scalable hydrothermal method followed by thermal calcination to activate surface bonding for Pd decoration. Decoration of Pd nanoparticles on the surface of WO3 was achieved through reduction of the complex Na2PdCl4 using Pluronic as both surfactant and reducing agent. The materials obtained were characterized by SEM, EDS, HRTEM, and XRD. The gas-sensing characteristics of bare WO3 and Pd–WO3 nanorods were tested for NH3, CO, H2, CO2, and CH4 detection at different temperatures. Results revealed that decoration of Pd nanoparticles on the surface of WO3 nanorods significantly enhances the NH3 gas-sensing characteristics of the metal oxide. The transient stability of the sensor determined after 10 on/off cycles of switching from air to gas demonstrated the effective reusability of the fabricated device.