Au@ZnO core-shell structure for gaseous formaldehyde sensing at room temperature

In this study, Au@ZnO core-shell structure was fabricated using the sol gel method to manufacture the sensing materials. The properties of the sensing material were analyzed with UV-vis spectra, X-ray diffraction spectra, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The ZnO material showed a 1.91 sensor response, whereas 1 wt% Au/ZnO exhibited a 5.58 sensor response. The response and recovery times of the 1 wt% Au/ZnO material measured 262 s and 134 s, respectively. Au@ZnO further enhanced the sensor response to 10.57 while reducing the response and recovery times to 138 s and 104 s, respectively. This study also demonstrates a formaldehyde gas-sensing mechanism involving HCHO adsorption, surface reaction and product desorption. Therefore, the favorable gas-sensing characteristics of the Au@ZnO core-shell structure make it a promising material for practical sensors.