A Facile Microwave Avenue to Electrochemiluminescent Two-Color Graphene Quantum Dots

With the assistance of microwave irradiation, greenish‐yellow luminescent graphene quantum dots (gGQDs) with a quantum yield (QY) up to 11.7% are successfully prepared via cleaving graphene oxide (GO) under acid conditions. The cleaving and reduction processes are accomplished simultaneously using microwave treatment without additional reducing agent. When the gGQDs are further reduced with NaBH4, bright blue luminescent graphene quantum dots (bGQDs) are obtained with a QY as high as 22.9%. Both GQDs show well‐known excitation‐dependent PL behavior, which could be ascribed to the transition from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) with a carbene‐like triplet ground state. Electrochemiluminescence (ECL) is observed from the graphene quantum dots for the first time, suggesting promising applications in ECL biosensing and imaging. The ECL mechanism is investigated in detail. Furthermore, a novel sensor for Cd2+ is proposed based on Cd2+ induced ECL quenching with cysteine (Cys) as the masking agent. Two‐color graphene quantum dots are prepared using a facile microwave‐assisted approach to have fluorescent quantum yields as high as 22.9%. The graphene quantum dots are demonstrated to be electrochemiluminescent. A novel electrochemiluminescence sensor for Cd2+ is proposed based on the competitive coordination between cysteine and graphene quantum dots for metal ions.