Abstract
Carbon dots (CDs) are a new class of nanomaterial discovered at the beginning of the 21st century. They have been extensively researched since then due to their promising properties and potential applications. However, there remains a great deal which is unknown about CDs, including their physical structure and the mechanism by which they emit light. This lack of clarity hinders the future applications of CDs in promising areas such as nanomedicine and photocatalysis, so a detailed study is compelled. Herein contains such an examination. First, a comprehensive structural characterization of CDs is undertaken to develop structural models for three different preparations of CDs. Next, a detailed investigation of CDs’ optical properties is undertaken before and after oxidation and reduction. This data, in conjunction with the structural model, is used to propose a mechanism for CDs’ photoluminescence. The potential to prepare red emissive CDs through various methods is also explored. Finally, some of CDs promising applications are highlighted through a fundamental investigation of CDs’ ability to sense metal cations, development of an immunoassay, and the preparation of self-targeting CDs to cross the blood-brain barrier. It is hoped that these fundamental and applied studies will enable the use of CDs in diverse future applications.