Tin oxide/graphene composite fabricated via a hydrothermal method for gas sensors working at room temperature

SnO2/graphene (GN) composite was fabricated via a simple one-pot hydrothermal method with graphene oxide (GO) and SnCl2 as the precursors. The composite was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction patterns, scanning electron microscopy and high resolution transmittance electron microscopy. It exhibited 3D nanostructure in which flower-like microspheres consisting of SnO2 nanoflakes distributed among GN layers decorated with tiny SnO2 nanoparticles, and was featured with high surface area (94.9 m2/g). GO is supposed to act as a template in the hydrothermal process, promoting the preferential growth of SnO2 nanocrystals and preventing the agglomeration of SnO2 nanoparticles. NH3 sensing characteristics of the composite at room temperature were investigated, and found to closely relate to its composition and structure. Under optimal conditions, the composite displayed high response magnitude (15.9% for 50 ppm NH3), fast response (response and recovery time < 1 min), good reversibility and repeatability. Moreover, it exhibited small temperature coefficients in the range of 15–45 °C. The ability of detecting gas at good room temperature of the composite is proposed to relate to its high specific surface, good conductivity of GN and interactions between GN and SnO2.