Fabrication of a Humidity-Resistant Formaldehyde Gas Sensor Through Layering a Molecular Sieve on 3d Ordered Mesoporous Sno2 Decorated with AU Nanoparticles

Abstract

The development of highly-sensitive and moisture resistant semiconductor metal oxide (SMO) gas sensors for practical application remains a challenge. Here, a three-dimensional ordered mesoporous (3DOM) SnO2 decorated with Au nanoparticles (NPs) was obtained via a facile self-assembly template method and the Au content was optimized. The 3DOM Au/SnO2 gas sensor displayed remarkable performance, with a response and a lower actual detection limit to formaldehyde 10.2 times higher and 500 times lower, respectively, compared to the undecorated 3DOM SnO2 sensor at 110 °C. Meanwhile, the fast response-recovery process and the repeatability, stability, and selectivity can meet the requirements for practical application. Density functional theory calculations revealed that the Au/SnO2 NPs have strong adsorption energies and electrical conductivity, allowing for selective formaldehyde detection. Further, the 3MCM-48 layer protects the 3DOM Au/SnO2 layer from moisture, allowing at least 80% of the initial response value to formaldehyde to be maintained even at > 90% relative humidity. Hence, the proposed strategy represents a universal and effective way to achieve high response and moisture-resistant formaldehyde sensors for the first time, and demonstrates the potential of SMO gas sensors for indoor air monitoring.

Keywords: moisture-resistant, Formaldehyde, 3DOM Au/SnO2, MCM-48, Gas Sensor