Room temperature NO₂ gas sensing of Au-loaded tungsten oxide nanowires/porous silicon hybrid structure

In this work, we report an enhanced nitrogen dioxide (NO₂) gas sensor based on tungsten oxide (WO₃) nanowires/porous silicon (PS) decorated with gold (Au) nanoparticles. Au-loaded WO₃ nanowires with diameters of 10 nm-25 nm and lengths of 300 nm-500 nm are fabricated by the sputtering method on a porous silicon substrate. The high-resolution transmission electron microscopy (HRTEM) micrographs show that Au nanoparticles are uniformly distributed on the surfaces of WO₃ nanowires. The effect of the Au nanoparticles on the NO₂-sensing performance of WO₃ nanowires/porous silicon is investigated over a low concentration range of 0.2 ppm-5 ppm of NO₂ at room temperature (25 ℃). It is found that the 10-Å Au-loaded WO₃ nanowires/porous silicon-based sensor possesses the highest gas response characteristic. The underlying mechanism of the enhanced sensing properties of the Au-loaded WO₃ nanowires/porous silicon is also discussed.