Graphene quantum dots prepared from chemical exfoliation of multiwall carbon nanotubes: An efficient photocatalyst promoter

•Grapheme quantum dots with strong electronic property have been prepared by chemical exfoliation.•GQDs/P25 nanocomposites as an efficient photocatalyst promoter have been prepared.•GQDs/P25 nanocomposites show much higher photocatalytic activity than P25 under visible-light irradiation.•GQDs play the crucial roles in GQDs/P25 nanocomposites for visible-light photocatalysis.

We report here a facile preparation of graphene quantum dots (GQDs) by chemical exfoliation of multiwall carbon nanotubes (MWCNTs) using a modified hummers' method. The resultant GQD samples possess strong electronic property, revealing great potential for photocatalyst design. As an efficient promoter, GQDs/P25 nanocomposites have been successfully prepared by simple wet impregnation and subsequent thermal annealing at 200 °C. In the tests of photocatalytic degradation of organic dyes under visible-light irradiation, the GQDs promoted P25 samples which shows much higher photocatalytic activity compared to the pure P25, indicating the crucial roles of GQDs.

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