Moisture reaction mechanism of Au-modified SnO2 ultrathin nanosheets with exclusive detection of formaldehyde

Exploring the reaction mechanism at the molecular level in detecting different target gases and providing the optimal operating temperature can improve selective detection performance and extend the lifetime of chemiresistors in practical sensing applications. While the humidity effect interaction mechanism between gas and sensor hinders its practical application. Therefore, exploring the reaction mechanism of humidity to detect different target gases at the molecular level can promote the development of exclusive detection performance and service life of sensors. To further disclose this, a one-step chemical method is applied to synthesize the defect-rich SnO2 with an ultrathin nanosheet structure. The experimental results confirmed that the inhibitory effect of humidity on the detection of formaldehyde by Au-SnO2 is significantly lower than that of other interfering volatile organic compounds (VOCs). The response value of Au-SnO2 detect 10 ppm of formaldehyde at 55 °C is 78, which is larger than that of methanol, ethanol, and acetone. This study sheds light on the mechanistic insight into the correlation between operating temperatures and humidity on the excellent performance of the Au-SnO2 chemiresistive sensor. We consider our work significant in developing highly efficient and stable electrochemical sensors to detect VOC gases at room temperature. •Defect-rich Au-SnO2 exhibits exclusive detection ability of formaldehyde.•The interface effect of Au-SnO2 enhance the electrons transfer ability.•The effect of water molecules toward Au-SnO2 detect formaldehyde is different from other VOC gases.•The detection mechanism between the VOC gases and Au-SnO2 are explored via DFT.