Microwave bottom-up route for size-tunable and switchable photoluminescent graphene quantum dots using acetylacetone: New platform for enzyme-free detection of hydrogen peroxide

• Published in: Carbon (New York) Vol. 81; pp. 514 - 524
• Main Authors: Umrao, Sima, Jang, Min-Ho, Oh, Jung-Hwan, Kim, Guntae, Sahoo, Sumanta, Cho, Yong-Hoon, Srivastva, Anchal, Oh, Il-Kwon
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2015; Elsevier
• Subjects: Acetylacetone; Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Fluorescence; Graphene; Hydrogen peroxide; Materials science; Microwaves; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Platforms; Quantum dots; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Enzymes; Acetylacetone; Hydrogen peroxide; Graphene; Microwave radiation; Quantum dots; Photoluminescence; Nanostructured materials
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2014.09.084

We report a microwave sequential bottom-up route to produce green and blue luminescent graphene quantum dots (g-GQDs and b-GQDs) with size-tunable and switchable functionalities by tailoring the diameter size and functional groups via microwave carbonization and aromatization processes from acetylacetone as a starting organic solvent. The b-GQDs as the final product show only one emission peak at 433nm and pH-independent blue luminescence, because two-step microwave irradiation could reduce the size and the oxygen-functional groups of the g-GQDs as an intermediate product. Also, the b-GQDs provide an exemplar enzyme-free platform for hydrogen peroxide detection through the electrochemical sensing due to much higher electron density and electron donating properties. In contrast, the g-GQDs show two different switchable photoluminescent emissions at ∼460nm (P1) and ∼500nm (P2): the P1 emission with sky-blue fluorescence originates from randomly conjugated oxygen-functional groups on the basal plane and/or edge of the g-GQDs and the P2 emission with green fluorescence results from quasi-molecular fluorophores formed by the electronic coupling of carboxylic acid groups.