Synthesis of nitrogen-doping carbon dots with different photoluminescence properties by controlling the surface states

Abstract

Surface states of carbon dots (CDs) are critical to the photoemission properties of CDs. By carefully adjusting the reaction conditions in a hydrothermal synthesis route, we have prepared a series of CDs with excitation-dependent emission (EDE) and excitation-independent emission (EIE) properties by controlling the content of nitrogen elements, confirming that the characteristic optical properties of CDs originate from their energy levels. It has been found that surface-passivation of the as-prepared CDs by nitrogen doping can improve the emission efficiency and be beneficial to EIE features due to the single electron transition resulting from the single functional groups. And the as-prepared CDs can specifically bind with Hg(2+) with the emission quenched because of the electron transfer from the LUMO levels of CDs to Hg(2+).

Miscanthus grass-derived carbon dots to selectively detect Fe3+ ions

“…42 All the doped MCDs (N-doped, P-doped, and dual-doped) possessed two absorption peaks. The presence of a secondary peak was also found in N-doped samples prepared by Yuan et al 44 The second peak most likely resulted from samples trapping energy in the excited states via the surface states; 45 which was previously reported in the literature and assigned to the n-p* transition of electrons in the carbogenic core. 46 FTIR spectra were recorded to conrm the presence of specic functionality in the MCDs and doped MCDs (Fig.…”

Near-infrared emissive carbon dots with 33.96% emission in aqueous solution for cellular sensing and light-emitting diodes

“…S11 online). When mixed with the CDs we prepared before [29], we successfully designed the white LEDs (Fig. 6c, d) with CIE of (0.34, 0.37) ( Fig.…”

“…Red fluorescence emitting materials are favorable for many applications, particularly in the biomedical fields, because blue light and ultraviolet light usually cause damage to biological tissues [22,23]. Since the discovery of CDs, researchers have explored a variety of synthesis pathways to prepare CDs from a variety of carbon sources, such as arc discharge, laser ablation [24,25], electrochemical synthesis [26,27], microwave [28,29], acidic oxidation, solvothermal methods [30,31], and hydrothermal methods [32][33][34][35]. Among these, hydrothermal and solvothermal methods are environmentally friendly and economical synthesis methods because the as-prepared CDs do not require further passivation.…”

Fe3+-Sensitive Carbon Dots for Detection of Fe3+ in Aqueous Solution and Intracellular Imaging of Fe3+ Inside Fungal Cells

“…But fluorescence intensity of the carbon dots was independent on pH in the ranges of 2-4 and 7-9. Protonation-deprotonation occurring on the surface of the carbon dots with pH variation induced the changes in the surface charges, resulting in pHdependence (Hu et al, 2014;Yuan et al, 2016;Liu et al, 2017). Therefore, if the carbon dots are used as bioimaging agents under the physiological pH condition, fluorescence intensity will hardly suffer from the pH variation.…”