Synthesis of oxygen-rich TiO2/coal-based graphene aerogel for enhanced photocatalytic activities

Abstract

Highly efficient nanocomposite with low-cost is greatly desired in dye-contaminated wastewater in recent years. Herein, a facile and cost-effective strategy was developed to synthesize TiO2/coal-based graphene aerogel (TCGA) through mild hydrothermal reduction coupled with freeze-drying using graphene oxide from graphitized bituminous coal as precursor. The obtained TCGAs have well-developed three-dimensional (3D) porous structure with high mechanical strength and ultra-low density, and contain uniform distribution of anatase TiO2 nanoparticles in cross-linked carbon skeleton as well as enriched in oxygen functional groups. Such unique structure features of TCGA not only can endow sufficient available space or active sites for dyes adsorption in aqueous solution, but also can provide efficient frameworks for photogenerated electrons stereo transportation in dyes photocatalytic decolorization process. When used as photocatalysts for the removal of dyes in aqueous solution, these prepared TCGAs have an excellent adsorption-photocatalysis synergistic effect, and exhibit a significantly enhanced photocatalytic activity, reliable reusability as well as good adaptability. The loading amount of TiO2 in such aerogels significantly affects the removal rate of dyes in adsorption-decolorization process. The optimized TCGA-40% shows a high removal capacity of 122.19 mg g−1 for rhodamine B, 134.38 mg g−1 for crystal violet, 113.78 mg g−1 for methyl orange, 113.45 mg g−1 for acid red and 99.55 mg g−1 for amino black in aqueous solution under ultraviolet light irradiation. Moreover, such TCGA-40% also exhibits an outstanding recyclability with 81.0% removal efficiency after experiencing 4 cycles use. This study paves a promising and universal way for large-scale production of TiO2/graphene aerogel composite for the elimination of organic dyes in wastewater.