Enhanced H2S gas sensing properties of multiple-networked Pd-doped SnO2-core/ZnO-shell nanorod sensors

Pd-doped SnO2-core/ZnO-shell nanorods were synthesized by using a three-step process: thermal evaporation of Sn powders in an oxygen atmosphere, atomic layer deposition of ZnO, and Pd diffusion followed by annealing. The sensitivity of the multiple networked SnO2-core/ZnO-shell nanorod sensor to H2S gas was found to be improved further significantly by Pd doping. The Pd-doped SnO2-core/ZnO-shell nanorod sensor showed sensitivities of 6.4, 15.4, and 36.2% at H2S concentrations of 20, 50, and 100 ppm at room temperature. The sensitivity of the nanorods was improved by more than 10 times at a H2S concentration of 100 ppm. The sensitivity enhancement of the SnO2-core/ZnO-shell nanorods by Pd doping may be attributed to the spillover effect, active reaction site generation, and the enhancement of chemisorption and dissociation of gas.