Green Synthesis of Biphasic\nTiO₂–Reduced\nGraphene Oxide Nanocomposites with Highly Enhanced Photocatalytic\nActivity

Abstract

A series of TiO₂–reduced graphene oxide\n(RGO)\nnanocomposites were prepared by simple one-step hydrothermal reactions\nusing the titania precursor, TiCl₄ and graphene oxide (GO)\nwithout reducing agents. Hydrolysis of TiCl₄ and mild reduction\nof GO were simultaneously carried out under hydrothermal conditions.\nWhile conventional approaches mostly utilize multistep chemical methods\nwherein strong reducing agents, such as hydrazine, hydroquinone, and\nsodium borohydride are employed, our method provides the notable advantages\nof a single step reaction without employing toxic solvents or reducing\nagents, thereby providing a novel green synthetic route to produce\nthe nanocomposites of RGO and TiO₂. The as-synthesized\nnanocomposites were characterized by several crystallographic, microscopic,\nand spectroscopic characterization methods, which enabled confrimation\nof the robustness of the suggested reaction scheme. Notably, X-ray\ndiffraction and transmission electron micrograph proved that TiO₂ contained both anatase and rutile phases. In addition, the\nphotocatalytic activities of the synthesized composites were measured\nfor the degradation of rhodamine B dye. The catalyst also can degrade\na colorless dye such as benzoic acid under visible light. The synthesized\nnanocomposites of biphasic TiO₂ with RGO showed enhanced\ncatalytic activity compared to conventional TiO₂ photocatalyst,\nP25. The photocatalytic activity is strongly affected by the concentration\nof RGO in the nanocomposites, with the best photocatalytic activity\nobserved for the composite of 2.0 wt % RGO. Since the synthesized\nbiphasic TiO₂–RGO nanocomposites have been shown\nto effectively reduce the electron–hole recombination rate,\nit is anticipated that they will be utilized as anode materials in\nlithium ion batteries.