Effect of Synthesis Process, Synthesis Temperature, and Reaction Time on Chemical, Morphological, and Quantum Properties of Carbon Dots Derived from Loblolly Pine

Abstract

In this study, carbon dots are synthesized hydrothermally from loblolly pine using top-down and bottom-up processes. The bottom-up process dialyzed carbon dots from hydrothermally treated process liquid. Meanwhile, hydrochar was oxidized into carbon dots in the top-down method. Carbon dots from top-down and bottom-up processes were compared for their yield, size, functionality, and quantum properties. Furthermore, hydrothermal treatment temperature and residence time were evaluated on the aforementioned properties of carbon dots. The results indicate that the top-down method yields higher carbon dots than bottom-up in any given hydrothermal treatment temperature and residence time. The size of the carbon dots decreases with the increase in reaction time; however, the size remains similar with the increase in hydrothermal treatment temperature. Regarding quantum yield, the carbon dots from the top-down method exhibit higher quantum yields than bottom-up carbon dots where the quantum yield reaches as high as 48%. The only exception of the bottom-up method is the carbon dots prepared at a high hydrothermal treatment temperature (i.e., 260 °C), where relatively higher quantum yield (up to 18.1%) was observed for the shorter reaction time. Overall, this study reveals that the properties of lignocellulosic biomass-derived carbon dots differ with the synthesis process as well as the processing parameters.

Development of Carbon Dots Synthesized from Green Tea and Alpha‐hydroxyl Acids with Enhanced Antioxidant Activity, Photostability and UV Protection Properties

“…The top‐down route can produce large CDs more effectively than the bottom‐up route because it starts with the larger size of raw materials whereas the bottom‐up route begins with small precursors. Consequently, U‐CDs are larger than T‐CDs, C‐CDs, and G‐CDs [39] …”

“…Consequently, U-CDs are larger than T-CDs, C-CDs, and G-CDs. [39] The surface structures and chemical compositions of the CDs were characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). As presented in Figure 3a, the broad bands at 3250-3400 cm À 1 were attributed to the OÀ H and NÀ H stretching vibrations, which were more prominent for the G-CDs than other CDs.…”

Biomass Derived Biofluorescent Carbon Dots for Energy Applications: Current Progress and Prospects

“…[125] Lignin depolymerizes above 260 °Cat hydrothermal conditions but the monomers do not cleave until 275-280 °C. [126] According to Quaid et al, (2022), [127] higher temperatures can encourage the development of sp 2 hybridized carbon structures inside C-dots. A reduced band gap as a result of the electrons' delocalization affects the emission wavelength and may increase the fluorescence intensity.…”

Carbon-Based Fluorescent Nano-Biosensors for the Detection of Cell-Free Circulating MicroRNAs

“…CNDs synthesized from biological sources play a significant role in biomedical and environmental applications, including bioimaging, biosensing, metal ions detection and electrocatalytic oxidations [52]. Green synthesis has attracted the interest of scientists because it is cost-effective, less hazardous, eco-friendly, less time-consuming, and requires lower temperatures (Table 1) [53].…”