The Influence of Functional Group on Photoluminescence Properties of Carbon Dots

Abstract

Two types of carbon dots (CDs) with different surface functional groups were prepared by using citric acid (CA) and glucose as carbon sources, which were named as CDs-CA and CDs-Glu. The differences of excitation wavelength dependent photoluminescence (PL) behavior and pH sensitivity were studied, which is caused by the differences of structure between CDs-CA and CDs-Glu. Detailed material characterization reveals that CDs-CA possesses higher PL intensity due to their rich surface functional groups (especially -NH2 with passivation effect). The variation trend of emission peak position to excitation wavelength for CDs-CA is also different from that for CDs-Glu. Emission peak position of maximum PL intensity of CDs-Glu is red-shifted compared to CDs-CA, which is ascribed to the higher graphitization degree. Besides, CDs-CA has higher pH sensitivity due to their more abundant functional groups on its surface. It is of great significance to understand the fluorescence mechanism of CDs.

Dual Photoluminescence Emission Carbon Dots for Ratiometric Fluorescent GSH Sensing and Cancer Cell Recognition

“…Moreover, the effects of pH on the sensing platform were further studied (Figure S9). The ratio of the probe (CDs–GSH) remains high and steady in the pH range of 3–7 and decreases gradually with the increase of pH, which is due to the deprotonation of carboxyl groups on the CDs and GSH surface. , …”

“…The ratio of the probe (CDs−GSH) remains high and steady in the pH range of 3−7 and decreases gradually with the increase of pH, which is due to the deprotonation of carboxyl groups on the CDs and GSH surface. 35,36 3.4. Possible Sensing Mechanism.…”

Synthesis and characterization nitrogen-doped carbon dots from candlenut shells using hydrothermal and solvothermal methods

“…Several functional groups, including -COOH, -OH, and -NH2, are present on the surface of CDs (Kou et al, 2020). Specifically, it has been shown that a higher concentration of functional groups on the surface of CDs increases the intensity of their luminescence (Liang et al, 2019). The emission of CDs is also affected by passivation agents.…”