Preparation and gas-sensing properties of holey ZnO nanosheets doped by gold nanoparticles

Holey ZnO nanosheets and their composites doped by gold nanoparticles were synthesized via a simple hydrothermal and calcination treatment. The composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption-desorption analysis. Experimental results demonstrate that the composites are composed of holey ZnO nanosheets and gold nanoparticles. The gold nanoparticles (with sizes of around 15 nm) are dispersed on the surface of ZnO nanosheets (with thicknesses around 20 nm). As the gold nanoparticles hinder the stacking of the ZnO nanosheets, the specific surface areas of the composites are significantly increased, and more gas-diffusion paths of the composites are available. Thus, the sensors based on holey ZnO nanosheets show high responses to alcohols, acetone, formaldehyde, xylene and toluene. Moreover, the sensors based on the holey ZnO nanosheets doped with gold nanoparticles exhibit higher sensitivity, especially the ZnO–Au-2 (4.0 wt% Au) sensor, which shows responses of 1043.6, 540.0 and 2822.7 towards 100 ppm acetone, ethanol and n-butanol, respectively. The sensor based on ZnO–Au-2 also shows good sensitivity to low-concentration acetone and n-butanol (detection limit about 0.2 ppm). Our results demonstrated that sensor based on 4.0 wt% gold doped ZnO nanosheets is promising candidates for medical diagnosis to detect low-concentration acetone.