ProQuest LLC, ProQuest Dissertations Publishing
2013
YUCHEN WANG
Carbon nanodots | Chemistry | Electronics | Fluorescence | Glass | Sensors | Sol-gel
Abstract
Carbon nanodots were synthesized from JEFFAMINE® T3000 and T5000 as carbon source and with no passivation agent. The transparent organic compound changed to dark brown solution, followed by 15 heating-cooling cycles in a 300 W microwave for 45 min. 1 mL deionized water was added to the cool down dark brown solution before centrifugation to extract C-dots from the solution. Finally, Cdots particles were well dispersed in the golden-yellow colored aqueous
supernatant. The possible mechanism of C-dots formation may include four steps: dehydration, polymerization, pyrolysis and self-passivation. Without post surface passivation process, we have demonstrated that the one-step microwave assisted method is a simple, rapid and green synthetic route for the production of watersoluble C-dots with highly intense photoluminescence (PL).
C-dots prepared through microwave pyrolysis were exhibited as uniform, spherical particles with small dimension and mono-dispersing in the solution in the TEM.
The prepared two types of C-dots displayed blue fluorescence under a UV-lamp
excitation and exhibited emission peaks centered at 448 nm and 439 nm
respectively. Moreover, our study showed that JEFFAMINE® T3000 and T5000 Cdots have the feature of 𝜆𝑒𝑥 dependent emission. The resulting photoluminescence of excited C-dots was spectrally broad in visible spectrum, with
peak intensity wavelength ranging from 400 nm to 500 nm with a dependence on the excitation wavelength from 325 to 405 nm.
The non-passivated JEFFAMINE® T3000 and T5000 C-dots synthesized by the one-step microwave assisted route were also demonstrated to be useful as a fluorescence sensor with their remarkably selectivity and sensitivity of Fe (III) ions over other interfere metal ions in water. In this metal ions quenching study, the observed perfect linear relationship between the relative fluorescence intensity respond to the addition of Fe (III) ions (up to 500 μM) suggests that the
JEFFAMINE® T3000 and T5000 C-dots could potentially be applied as excellent sensor materials for the detection of Fe (III) with high sensitivity and selectivity.
Meanwhile, the sol-gel thin film immobilization of the JEFFAMINE® T3000 and
T5000 C-dots was studied, however more intensive research effort to generate an
applicable sol-gel immobilization of C-dots sensor is still required in the future.
Due to the advantages of low cost, easy preparation, high sensitivity and selectivity,
T3000 and T5000 C-dots can be developed as a promising eco-friendly sensing probe for the detection of Fe (III) ions in a real sample in the near future.