A room temperature NH 3 gas sensor based on a quartz crystal microbalance coated with a rGO-SnO 2 composite film.

Novel QCM NH 3 gas sensors made of reduced graphene oxide-SnO 2 (rGO-SnO 2 ) composite films were fabricated using a one-pot technique, which is a fast and easy fabrication route that is useful for practical applications. The surface morphology and composition of the rGO-SnO 2 composite films were analyzed using Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy coupled with energy-dispersive X-ray elemental mapping and transmission electron microscopy. On the basis of the microstructural observations, SnO 2 connected to rGO sheets and naked rGO sheets were observed on the surface of the rGO-SnO 2 composite films. The effects of the amount of added rGO sheets on the enhancement of the NH 3 gas sensing properties of the rGO-SnO 2 composite films were studied. The analysis of the adsorption dynamics (association constant) confirmed the higher sensitivity of the QCM NH 3 gas sensor based on the rGO-SnO 2 composite film than that of the sensor with the pristine SnO 2 film.