Hydrothermal synthesis of 3D urchin-like Ag/TiO2/reduced graphene oxide composites and its enhanced photocatalytic performance

Abstract

Innovative 3D urchin-like ternary TiO2 composites, which combine Ag nanoparticles with graphene, have been successfully synthesized through a simple hydrothermal method. This process employed nontoxic and mild dihydrate sodium citrate as a reducing agent. During the hydrothermal process, graphene oxide and AgNO3 were reduced to reduced graphene oxide (RGO) and Ag, respectively. Subsequently, they were grown on the surface of rutile TiO2 with a 3D urchin-like microsphere (1.5 μm). The as-prepared 3D urchin-like composites were characterized by X-ray diffraction, SEM and TEM. These techniques were also employed to ensure the morphology of urchin-like and rutile phase of TiO2. FT-IR, Raman spectroscopy and XPS characterization demonstrated the successful reduction in AgNO3 and graphite oxide to metallic Ag and RGO. The UV–visible spectrum of the ternary composite displayed strong absorption in the visible light region, which was attributed to the efficient electron transport of well-dispersed Ag nanoparticles (20–40 nm) and the formation of Ti–O–C bond between graphene and titania. The synthesized urchin-like ternary composite exhibited enhanced photocatalytic activity (98.7 %) for Rhodamine B degradation. This work provides a very convenient chemical route to the scalable production of Ag/TiO2/RGO ternary composite photocatalyst for potential applications in solving the environmental problems and energy issues. Also, the proposed mechanism underlying the photocatalytic degradation of Rhodamine B dyes was discussed. Fourier transform infrared (FTIR) spectra of pure UT, UTG and Ag–UTG composite. The scheme of proposed mechanism for the photocatalytic degradation of RhB on Ag–UTG.