Light Trapping-Mediated Room-Temperature Gas Sensing by Ordered ZnO Nano Structures Decorated with Plasmonic Au Nanoparticles

An ordered array of 1D ZnO nanorods obtained by colloidal templating is shown to dramatically enhance the sensing response of NOx at room temperature by confining light and creating periodic structures. The sensitivity is measured for a concentration varying from 2 to 10 ppm (response 53% at 10 ppm) at room temperature under white light illumination with approximate to 225 nm hole diameter. In contrast, structures with approximate to 450 nm hole size show better sensing under (response 98% at 10 ppm) elevated temperatures in dark conditions, which is attributed to the increased surface chemical interactions with NOx molecules due to the porous nature and enhanced accessible surface area of ZnO nanorods. Further, the decoration of ZnO Nanorods with gold nanoparticles shows enhanced sensor performance (response 130% at 10 ppm) due to localized surface plasmon resonance under white light illumination. The findings may lead to new opportunities in the visible light-activated room-temperature NOx sensors for healthcare applications.