Hollow zinc oxide microspheres functionalized by Au nanoparticles for gas sensors

We present a facile one-step template-free route for the synthesis of homogeneous Au-loaded ZnO hollow spheres composed of nanoparticles. The synthesis was performed at a relatively low temperature (90 °C) with short reaction duration (40 min). Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDX) analysis revealed that Au nanoparticles were homogeneously embedded into ZnO spherical shell, which was composed of nano-sized primary particles. Furthermore, to investigate the influence of Au nanoparticles on the sensor performance, the gas sensing properties of Au-loaded ZnO were studied. A comparative gas sensing investigation between the Au-loaded ZnO and pure ZnO hollow spheres was performed to display the superior sensing properties of the loaded samples. As expected, the sensor using 1.0 mol% Au-loaded ZnO exhibited a high response and fast response and recovery properties to ethanol, which could be attributed to the catalytic effect of Au.