Skip to main content
. 2019 Dec 4;4(25):21223–21229. doi: 10.1021/acsomega.9b02686

Figure 1.

Figure 1

(a) Schematic for synthesis process of carbon dots (CDs). Initially, the solution is clear. Gradually, with the increase in reaction temperature and time, nucleation followed by growth (steps 1, 2) takes place with a change in color of the solution from pale yellow to brown. Surface functionalization will take place for SFCDs in step 3. (b) The corresponding meaning of steps 1, 2, and 3 in the reaction mechanism is explained. Carbon dots are formed by pyrolysis and then carbonization of citric acid. ODE acts as a high-boiling-point solvent. For SFCDs, HDA acts as a surface-functionalizing agent. (c) The synthesized bare CDs under UV light show white-light emission. SFCDs under UV light show blue (452 nm) to green (541 nm) color emissions at different HDA/citric acid molar concentrations. Blue light for sample with molar concentration ratio HDA/citric acid = 0.3, and green color for samples with molar concentration ratios HDA/citric acid = 0.6, 1.0, and 1.3 (from left to right).