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Abstract: An aqueous dispersion of reduced graphene oxide (rGO) has been successfully prepared via chemical reduction of graphene oxide (GO) by hydrazine hydrate in the presence of aniline for the first time. The noncovalent functionalization of rGO by aniline leads to a rGO dispersion that can be very stable for several months without the observation of any floating or precipitated particles. Several analytical techniques including Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) have been used to characterize the resulting rGO. Taking advantages of the fact reducing ability of aniline toward AgNO3, we further demonstrated the subsequent decoration of rGO with Ag nanoparticles (AgNPs) by in situ chemical reduction of silver salts. It was found that such AgNP/rGO nanocomposites exhibit good catalytic activity toward the reduction of hydrogen peroxide (H2O2), leading to an enzymeless sensor with a fast amperometric response time of less than 2s. The linear detection range is estimated to be from 100μM to 80mM (r =0.9991), and the detection limit is estimated to be 7.1μM at a signal-to-noise ratio of 3. [Copyright &y& Elsevier]

Abstract: SnO2 nanoparticles-reduced graphene oxide (SnO2-rGO) nanocomposites have been successfully prepared by a facile method via hydrothermal treatment of aqueous dispersion of GO in the presence of Sn salts. The combined characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) indicate the successful formation of SnO2-rGO nanocomposites. To demonstrate the product on sensing application, gas sensors are fabricated using SnO2-rGO nanocomposites as sensing materials and investigated for detection of NO2 at low operating temperature (50°C). It is found that SnO2-rGO nanocomposites exhibit high response of 3.31 at 5ppm NO2, which is much higher than that of rGO (1.13), and rapid response, good selectivity and reproducibility. Furthermore, the reason for enhancing sensing performance by addition of SnO2 nanoparticles has also been discussed. [Copyright &y& Elsevier]

Abstract: In this paper, we develop a cost-effective and simple route for the synthesis of Au nanoparticles (AuNPs) decorated graphene oxide (GO) nanosheets using polyoxyethylene sorbitol anhydride monolaurate (TWEEN 20) as a stabilizing agent for GO as well as a reducing and immobilizing agent for AuNPs. The AuNPs assemble on the surface of TWEEN-functionalized GO by the in situ reduction of HAuCl4 aqueous solution. The morphologies of these composites were characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). It is found that the resultant AuNPs decorated GO nanosheets (AuNPs/TWEEN/GO) exhibit remarkable catalytic performance for hydrazine oxidation. This hydrazine sensor has a fast amperometric response time of less than 3s. The linear range is estimated to be from 5μM to 3mM (r =0.999), and the detection limit is estimated to be 78nM at a signal-to-noise ratio of 3. The AuNPs/TWEEN/GO composites also exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the GO supports also enhance the catalytic activity via a synergistic effect. [Copyright &y& Elsevier]