TeO2–decorated W18O49 nanorods with highly enhanced gas-sensing performance towards nitrogen dioxide

Surface functionalization is an effective approach for improving the gas-sensing capabilities of one-dimensional (1D) metal oxides. In this work, tellurium dioxide nanoparticles–decorated tungsten oxide nanorods (TeO2 NPs@W18O49 nanorods) were prepared via a facile two-step process, i.e. solvothermal synthesis of W18O49 nanorods followed by hydrolysis deposition of TeO2 NPs, for gas-sensing applications. In the TeO2 decoration process, sodium dodecyl benzene sulfonic acid was introduced as surfactant to assure formation and attachment of highly discrete, tiny TeO2 NPs on whole surface of nanorods. The microstructures of the decorated nanorods were characterized, and the effect of TeO2 decoration on the gas-sensing characteristics of W18O49 nanorods was investigated. It is found that TeO2 decoration reduces the optimal operating temperature of W18O49 nanorods-based sensor from 200 to 150 °C. The W18O49 nanorods decorated with discrete TeO2 NPs display about four-fold enhancement in gas response to 0.1–1 ppm NO2 at 150 °C compared to pure W18O49 nanorods. The underlying mechanism for the enhanced response of the decorated sensor was demonstrated based on an electronic sensitization-related conductance effect model.