Multicolor Functional Carbon Dots via One-Step Refluxing Synthesis

Abstract

Carbon dots are admirable fluorescent nanomaterials due to their low cost, high photostability, excellent biocompatibility, and environmental friendliness. Most conventional carbon dot fabrication approaches produce single-colored fluorescent material in the preparation process; different methods are therefore required to synthesize distinct carbon dots for specific optical applications. In this study, carbon dots carrying different emission colors are prepared through a one-step refluxing process. The emission of these materials can be well-tuned by sodium hydroxide content in the precursor solution. The carbon dots produced are used as sensing probes based on the spectrofluorometric inner filter effect for target molecule detection. Three sensing categories that combine carbon dots and inner filter effect are demonstrated, including direct, metal nanoparticle-assisted, and enzymatic reaction-supported detection. Caffeine, melamine, and fenitrothion are selected as targets to demonstrate the strategies, respectively. These multifunctional carbon dot-based sensors achieve comparable sensitivity toward analytes with a much more convenient preparation route.

Recent Developments in Synthesis and Photocatalytic Applications of Carbon Dots

“…In addition, reflux methods are widely used for CD production. Wang et al [20] synthesized multicolor CDs by a one-step reaction of L-cysteine and D-galactose upon reflux, showing that multicolor properties could be controlled by varying the concentration of NaOH. Yellow (10.4 ± 1.2 nm), green (6.1 ± 0.6 nm), and blue (3.3 ± 0.5 nm) CDs were produced in the presence of 0.1, 0.2, and 0.4 M NaOH, respectively, i.e., CD size decreased with increasing NaOH concentration, which was ascribed to the concomitant slowdown of isotropic growth.…”

A Facile, Effective Synthesis of Excellent Fluorescent Carbon Dots with Optical Properties

“…However, different characteristics can be observed in the lower‐energy absorption bands. Again, as shown in Figure it clearly seen that the absorption edges of c‐CDs show red shifts compares with a‐CDs and b‐CDs samples, indicating that the optical absorption in visible light is enhanced . The first absorption band, from λ=270 nm to 300 nm, is due to the π‐π* transition of C=O bond.…”

“…In most of the cases, hydrothermal approach is popular in preparation of nanomaterials. Such approach was carried out under high temperature and high pressure, thus, some organic molecules such as citric acid, glucose, and chitosan can be carbonized to obtain carbon dots …”

Hydrochromic carbon dots as smart sensors for water sensing in organic solvents

“…Specic synthetic strategies that can take advantage of these two types of emission are used for the formation of multiple color emitting carbon dots. [32][33][34][43][44][45][46] Nevertheless, few studies report the systematic optimization of such carbon dots developed through carbonization. 43,[47][48][49][50][51][52][53][54][55][56][57] Additionally, signicant research reports have shown the solvent-dependent emission of carbon dots.…”