Fabrication of a Au@SnO2 core-shell structure for gaseous formaldehyde sensing at room temperature

This paper describes the fabrication of a Au@SnO2 core-shell structure using the sol gel method to manufacture the sensing materials. The properties of the sensing material were analyzed with UV-vis spectra, Fourier transform infrared spectroscopy, and transmission electron microscopy. The SnO2 material showed no response, whereas 1 wt% Au/SnO2 exhibited a 2.4 sensor response. The response t90 (for a result equaling 90% of the equilibrium signal) and recovery tr90 (to adjust the signal to 90% background signal) times of the 1 wt% Au/SnO2 material measured 240 s and 210 s, respectively. Au@SnO2 further enhanced the sensor response to 2.9 while reducing the response and recovery times to 80 s and 62 s. This study also demonstrates a formaldehyde gas-sensing mechanism involving HCHO adsorption and surface reaction and product desorption.