Upconversion and Downconversion Fluorescent Graphene Quantum Dots: Ultrasonic Preparation and Photocatalysis
Shujuan Zhuoa,b, Mingwang Shaoa,*, Shuit-Tong Leec,*
aInstitute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China
bAnhui Key Laboratory of Functional Molecular Solids, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, P. R. China
cCenter of Super-Diamond and Advanced Films and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, P. R. China
A facile ultrasonic route for the fabrication of graphene quantum dots (GQDs) with upconverted emission is presented. The as-prepared GQDs exhibit an excitation-independent downconversion and upconversion photoluminescent (PL) behavior. And the complex photocatalysts (rutile TiO2/GQD and anatase TiO2/GQD systems) were designed to harness the visible spectrum of sunlight. It is interesting that the photocatalytic rate of rutile TiO2/GQD complex system is ca. 9 times larger than that of anatase TiO2/GQD complex under visible light (λ > 420 nm) irradiation in the degradation of methylene blue.