Abstract

A novel NO₂ gas sensor has been constructed using Ag nanoparticles-SnO₂ nanoparticles-reduced graphene oxide (AgNPs-SnO₂-rGO) hybrids as sensing materials. AgNPs-SnO₂-rGO hybrids were prepared by a two-step wet-chemical method. Firstly, SnO₂-rGO hybrids were synthesized by hydrothermal treatment of aqueous dispersion of GO in the presence of SnCl₄. Then, AgNPs-SnO₂-rGO hybrids were obtained by in situ reduction of AgNO₃ on the surface of SnO₂-rGO hybrids. The combined characterizations of UV?Cvis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDX), elemental mapping, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and Raman spectra were used to investigate the structure of AgNPs-SnO₂-rGO hybrids. Most importantly, the sensor based on AgNPs-SnO₂-rGO hybrids exhibits good sensing performance for NO₂ sensing operating at room temperature. For example, the response time and recovery time of the sensor based on AgNPs-SnO₂-rGO hybrids for 5 ppm NO₂ are 49 s and 339 s, which are much shorter than that of SnO₂-rGO hybrids (415 s and 740 s), indicating that the sensing performances for NO₂ sensing at room temperature have been tremendously enhanced by introduction of AgNPs into SnO₂-rGO hybrids.