Nitrogen and Sulfur Co‐Doped Carbon Quantum Dots for Sensing Applications: A Review

Carbon quantum dots (CQDs) have emerged in the last decade, outperforming other members of the carbon family due to remarkable properties such as fluorescence, cytocompatibility, photostability, and other chemical properties, which have led to an increasing number of applications in bioimaging, sensing, photovoltaic, and medicine. Nature is a treasure trove of exciting precursors, which inspires constant persuasion of safe synthetic routes. Doped CQDs, in particular, exhibit excellent luminous characteristics and have been effectively used in various applications. Among the different doping methods used to tune the properties of CQDs, nitrogen (N) and sulfur (S) are the most commonly used elements with comparable atomic sizes, strong valence bonds, and similar electronegativity. As a result, the last lustrum has seen a significant increase in several synthetic approaches to NSCQDs. This is an attempt to review the journey of NSCQDs through green and chemical sources of synthesis and their sensing applications.