Surrounding Media Sensitive Photoluminescence of Boron-Doped Graphene Quantum Dots

Graphene is a zero-bandgap semiconductor, no optical luminescence is observed in pristine graphene. A bandgap, however, can be engineered into graphene quantum dots (GQDs) due to quantum confinement and edge effects. As a result, luminescent GQDs have attracted great attention as one of highly promising nanomaterials due to their exceptional advantages of low cytotoxicity, excellent solubility, stable photoluminescence (PL), fine biocompatibility as well as low-cost.^[1] Above these fascinating merits in GQDs distinguish themselves from traditional fluorescent materials, making them perfect alternatives for numerous exciting applications: bioimaging,^[2] fluorescence sensors,^[3[ fuel cells,^[4] photovoltaic devices.^[5]

Doping carbon materials with heteroatoms can effectively tune their intrinsic properties, thus producing new phenomena and unexpected characteristics. Although veriouse heteroatom-doped carbon materials have been reported, doped GQDs have been much less studied. Herein, we report a facile one-pot electrochemical approach for the synthesis of boron(B) doped GQDs (B-GQDs) with B content of 5.24 at %, in which only borax was used as the electrolyte without any other chemical additives. The as obtained water-soluble B-GQDs feature intriguing tunable fluorescence, act as a Al³⁺fluorescent sensor, cellular imaging and electrocatalysts for the oxygen reduction reaction. With the existence of borax, they show strong green luminescence with a quantum yield as high as 13%. Significantly, green fluorescent crystals were obtained from evaporating the aqueous solution in the presence of borax at room temperature.

Acknowledgements

This work is supported by NSFC (21073018), the Major Research Plan of NSFC (21233003), Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, Beijing Normal University.

References

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