Cross-Linked SnO2 Nanosheets Modified by Ag Nanoparticles for Formaldehyde Vapor Detection

Ag@SnO2 nanosheets were prepared through a hydrothermal method followed by heat treatment and a liquid reduction process. Many Ag nanoparticles (Ag NPs) were dispersed uniformly over the surface of the SnO2 nanosheets. The thickness of the SnO2 nanosheets was approximately 10 nm. After decoration with Ag NPs, the Ag@SnO2 nanosheet sensors exhibited improved gas-sensing behaviors compared to the pure SnO2 nanosheet sensor. The response of cross-linked SnO2 nanosheets decorated by Ag NP sensors for 100 ppm formaldehyde vapor was up to 101.4, which was double that (45.5) of the pure SnO2 nanosheet sensor. The response and recovery times of the Ag@SnO2 sensor were 21 s and 23 s, respectively. The Ag@SnO2 nanosheet sensors showed reasonable cycling stability, as demonstrated by testing with 100 ppm formaldehyde 10 times. The superior gas-sensing behaviors of the Ag@SnO2 sensor were due to the large specific surface area, cross-linked nanostructure, and synergistic effect of the Ag NPs with huge sensitizing active sites and numerous SnO2 nanosheets.