Enhanced CH4 sensing properties of Pd modified ZnO nanosheets

In this paper, pristine ZnO and Pd modified ZnO nanosheets have been successfully prepared via a facile hydrothermal route and the subsequent calcination process. The composition, morphology and nanostructure of the as-obtained materials were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The methane (CH4) sensing properties of Pd/ZnO were compared with those of pure ZnO, and the materials showed the noticeable sensing capability when the loading amount of Pd was 1 at%. Moreover, the optimal working temperature of ZnO was reduced from 240 degrees C to 200 degrees C after loading Pd. The synthesized 1% Pd/ZnO nanocomposites not only showed the maximum response value 19.20 toward 5000 ppm CH4 at 200 degrees C, but also exhibited the excellent selectivity and good repeatability. The improvement of CH4 sensing performance by Pd nanoparticles could be attributed to the synergy effect with the spill-over effect and the nano-Schottky barriers.