Garlic was used as a green source to synthesize carbon dots (CDs) with a systematic study of the optical and structure properties. Ethylenediamine was added into the synthesis to improve the photoluminescence quantum yield (PL QY) of the CDs. Detailed structural and composition studies demonstrated that the content of N and the formation of C-N and C=N were critical to improve the PL QY. The as-synthesized CDs exhibited excellent stability in a wide pH range and high NaCl concentrations, rendering them applicable in complicated and harsh conditions. Quenching the fluorescence of the CDs in the presence of Fe(3+) ion made these CDs a luminescent probe for selective detection of Fe(3+) ion.

Department of Engineering Science and Mechanics The Pennsylvania State University University Park Pennsylvania 16802 USA

Department of Physical Chemistry Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University in Olomouc Šlechtitelů 27 783 71 Olomouc Czech Republic

State Key Laboratory of Superhard Materials and College of Physics Jilin University Changchun 130012 China

State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering Jilin University Changchun 130012 China

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