Efficient synthesis of silver-reduced graphene oxide composites with prolonged antibacterial effects

In this work, we successfully synthesized the silver-reduced graphene oxide (Ag-rGO) composites based on the in situ growth of Ag nanoparticles (NPs) on the surfaces of the GO sheets through a one-pot solvothermal method without using any surfactants or modifiers. The as-synthesized Ag-rGO composites have been characterized by X-ray diffraction, X-ray photoelectron spectrometry and electron microscopy. Results showed that high-density Ag NPs and dots with uniform size distribution were grown on the surfaces of the GO sheets, accompanied by the reduction of GO to rGO. By simply changing the concentration of Ag+ ions in the solvothermal reaction system, the size and distribution of the Ag nanocrystals could be controlled. The antibacterial properties of the Ag-rGO composites were investigated by combined techniques of inhibition zone method, plate colony-counting method and bacterial growth curve. The Ag-rGO composites have been found to exhibit excellent antibacterial properties with long-term effects, which could effectively inhibit the growth of bacteria of Vibrio natriegens and Bacillus sp. 1NLA3E. The strongly-coupled interaction between the Ag nanocrystals and the rGO supports as well as the presence of the Ag dots contributed equally to the prominent long-term antibacterial performance of the Ag-rGO composites. The present Ag-rGO composites may find important environmental applications.