Carbon Dots for Carbon Dummies: The Quantum and The Molecular Questions Among Some Others

Abstract

Carbon Dots (CDs) are carbon nanoparticles which were discovered in 2004. Despite two decades of intensive work from the scientific community and a colossal amount of gathered experimental data, no definitive consensus exists to date on several key aspects such as the actual definition of CDs and the origin of their emissive properties. This review proposes a critical evaluation of these fundamental questions. Lay persons will also find here an alternative introduction to the CDs domain, including synthetic strategies, photophysical properties, as well as challenges and outlook of this exciting new area.

Tailoring the Chemical Structure of Nitrogen‐Doped Carbon Dots for Nano‐Aminocatalysis in Aqueous Media

“…Moreover, if we compare the value of the acid/base sites in the initial mixture of precursors, it is possible to quantify retained sites on NCDs surfaces. In fact, some of the initial starting material acid/base moieties are lost during the synthesis due to decarboxylation reactions, dehydration, formation of amide bonds and appearance of molecular side‐products that are removed from NCDs during the purification step [5,38,39] . Specifically, up to 50 %±4% of sites are retained for NCDs‐ 2 compared to just 20 %±4% for NCDs‐ 1 , showing a steep increase in the bi‐component synthesis with respect to the mono‐component approach (Figure 3f).…”

“…In fact, some of the initial starting material acid/base moieties are lost during the synthesis due to decarboxylation reactions, dehydration, formation of amide bonds and appearance of molecular side-products that are removed from NCDs during the purification step. [5,38,39] Specifically, up to 50 % � 4% of sites are retained for NCDs-2 compared to just 20 % � 4% for NCDs-1, showing a steep increase in the bicomponent synthesis with respect to the mono-component approach (Figure 3f). Interestingly, a clear correlation can be observed between the total number of acid/base sites, the percentage of retained sites, and the length of the DA used (see Section B.2.3 of the Supporting Information).…”

“…Carbon dots (CDs) are an emerging class of quasi‐spherical carbon‐based nanoparticles with dimensions below 10 nm [1–4] . In recent years, these nanomaterials have gained popularity thanks to their excellent luminescence and optical features, considerable solubility in aqueous and polar solvents, high chemical and photostability, as well as their low toxicity and excellent biocompatibility [3,5,6] . Moreover, CDs can be readily produced from inexpensive and abundant molecular precursors through straightforward and robust bottom‐up synthetic protocols [7,8] .…”

“…[1][2][3][4] In recent years, these nanomaterials have gained popularity thanks to their excellent luminescence and optical features, considerable solubility in aqueous and polar solvents, high chemical and photostability, as well as their low toxicity and excellent biocompatibility. [3,5,6] Moreover, CDs can be readily produced from inexpensive and abundant molecular precursors through straightforward and robust bottom-up synthetic protocols. [7,8] Interestingly, when molecules are used as precursors, the structure of the resulting CDs may reflect the molecular features of the starting materials.…”

Chiral Carbon Nanodots Can Act as Molecular Catalysts in Chemical and Photochemical Reactions

“…In recent times, the commonly employed synthetic strategy for the preparation of these materials has relied on the solvothermal treatment of small organic molecules. Indeed, the appropriate selection of starting materials, doping agents, and synthetic conditions affords CNDs with tailored structural and optical properties [3–5] . Among other possible applications, CNDs can be considered as a new generation of nano‐catalysts.…”