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

Abstract

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.

Colloidal Quantum Dots: Synthesis, Composition, Structure, and Emerging Optoelectronic Applications

“…In addition to the earliest core/ligands shell structure, scientists have successively developed doping, [140,144] alloy, [145] coreshell [146] structures (Figure 8, all represented by common spherical structures). Different structures have their own characteristics.…”

“…Due to their green synthesis, low toxicity and stable photoluminescence, CDs are undoubtedly the most successful of all quantum dots for biomedical applications. [ 11b,24b,140 ] Based on their strong UV–vis absorption, downconversion capability, and narrow emission, CDs are also gradually assuming an important role in the preparation of LED, PD, LD, and PC devices (Figure 7b). [ 13b,22,141 ] However, the drawback of CDs are the relatively poor conductivity and low PLQY.…”

Fluorimetric determination of Vonoprazan via quenching of nitrogen and sulfur co‐doped carbon quantum dots: A rapid and sustainable analytical approach

“…Nitrogen (N) and sulfur (S) are commonly employed as doping elements in CQDs due to their comparable atomic sizes (the radius of C: 0.77, N: 0.75, S: 1.09), strong valence bonds, and greater electronegativities than carbon (electronegativity of C:2.55, N:3.4, S:2.58). Doping with N and S atoms generates extra electron pairs and defect sites, enhancing the number of active sites on the surface of CQDs, resulting in improved photoluminescent properties [29][30][31][32][33].…”