Au nanoparticle-decorated porous SnO2 hollow spheres: a new model for a chemical sensor

Au nanoparticle-decorated porous SnO2 hollow spheres, which are different from the conventional noble metal-doped thick or thin semiconductor films, are prepared and systematically investigated as a new model for chemical gas sensors. The synthesized Au-decorated porous SnO2 hollow spheres are characterized by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The Au content in the SnO2 support was determined as 5.63 wt% by XPS and 5.90 wt% by ICP, respectively, indicating the homogeneous dispersion of Au nanoparticles on SnO2 hollow spheres. Experimental results show that, by using ethanol as a probe molecule, this new model exhibits excellent sensing performances in terms of high response, fast response-recovery, superior selectivity and good stability. The enhanced sensing features are attributed to the improved gas diffusion and mass transport induced by the unique porous structure, the formation of conjugated electron depletion layers on both the outer and inner surfaces of the SnO2 hollow spheres and the catalytic effect of the Au nanoparticles. It is believed that the strategy of combining the porous nanostructure and catalytic activity of noble metals can further provide potential for other applications.