The H2 sensing properties of facets-dependent Pd nanoparticles-supported ZnO nanorods

The loading of noble-metal nanoparticles (NPs) is an effective approach for the enhancement of H2 sensing performances, although there have been rare reports focused on the effect of the facets of noble-metal nanoparticles in the H2 sensing performance. The catalytic and adsorption performance of noble-metal nanocrystals is mainly determined by their exposed facets, while the gas sensing performance of sensors is strongly correlated to the adsorption and reaction between the gases and sensor materials. Hence, it is very important to study the gas sensing performance of the different facets-exposed noble-metal nanoparticles. In this study, a set of shape-controlled Pd NPs have been prepared and loaded onto the ZnO nanorods, and the gas sensing performance of the Pd nanoparticle-loaded ZnO to 250 ppm of H2 has been detected. The results indicate that the cubic Pd NPs-loaded ZnO shows higher and faster sensing response to H2 than the octahedral and spherical Pd-loaded ZnO owing to the stronger adsorption of the H2 by cubic Pd NPs enclosed by (100) facets than the octahedral NPs enclosed by (111) facets. The cubic Pd NPs-loaded ZnO also exhibits better sensing selectivity and repeatability towards H2.