Room-temperature flexible ammonia sensor based on SnO2 quantum dots modified graphene oxide

Abstract

Tin dioxide quantum dots (SnO2 QD) were prepared by hydrothermal method, and then SnO2 QD modified graphene oxide (SnO2 QD@GO) was synthesized by a secondary hydrothermal technique to fabricate a flexible sensor for detecting ammonia at room temperature. The morphology, structure and composition of the composites were analyzed by SEM, TEM, EDS, XPS, XRD and Raman spectroscopy. TEM images showed that SnO2 QD with a diameter range of 5–8 nm present a cuboid structure, embedded in the two-dimensional GO surface. The gas sensing test shows that at room temperature the response of SnO2 QD@GO to ammonia is 5 times higher than that of GO. At the same time, the operating temperature of pure SnO2 QD is greatly reduced from 250 °C to room temperature (24 °C) by the composing of GO. Flexibility test of SnO2 QD@GO was also measured to test the fatigue resistance and bending test of the device. The improved ammonia sensing performance of SnO2 QD@GO is mainly due to the smaller bond energy of ammonia and abundant functional groups of GO, which provides more active sites for the surface adsorption of NH3.