Green Synthesis of Carbon Dots and Their Application as Photocatalyst in Dye Degradation Studies

摘要

This paper presentswork on green synthesis of the carbon dots from leaves of Elettaria cardamomum (E.C) using simple ultrasonicationtechnique. In X-ray diffraction analysis, peak at 2θ value of 22.9° confirmed the amorphous nature of synthesizedcarbon dots. Furthermore, Raman investigations of the synthesized carbon dots illustrated D and G band at 1365 cm~(−1)and 1575 cm~(−1), respectively, showing graphitic structure of carbon dots. Similarly, Fourier transform infrared spectrumof carbon dots confirmed the presence of different functional groups such as C=O, C=C, OH, C–OH at absorption peaksvalues of 1715 cm~(−1), 1634 cm~(−1), 3257 cm~(−1) and 1027 cm~(−1), respectively. Photoluminescence spectral analysis of carbondots confirms photoluminescent nature by exhibiting two emission peaks at 520 nm and 850 nm, respectively. UV–visiblespectrophotometric investigations confirmed the presence of carbon dots showing two absorption peaks at 220 nm and272 nm. After confirmation and characterization, the synthesized carbon dots were utilized for studying visible light-induceddegradation of congo red and methylene blue dyes. This further investigation showed that the maximum degradation of congored dye was observed in acidic media at pH 4 with a dye concentration of 5 ppm in a time interval of 50 min. For methyleneblue dye, optimum degradation was observed in alkaline medium at a pH value of 8 with 5 ppm dye concentration in a timeinterval of 55 min.