Exploring the Potential of Rare Earth Doped Carbon Dots: Concepts and Applications

Carbon dots (CDs) are nanostructures containing mainly carbon atoms and abundant functional groups. With remarkable and adjustable physicochemical properties, CDs have excellent hydrophilicity, photoluminescence (PL), biocompatibility, and low toxicity. Although the numerous advantages make CDs a research target for synthesizing advanced materials, some limitations are pertinent and must be corrected. Rare earth elements (RE) are excellent candidates for doping CDs, obtaining hybrid materials called RE-CDs to optimize luminescence properties, applicability, and quantum yields. Hybrids allow the combination of the advantageous characteristics of both CDs and RE, drastically improving their luminous and magneto-optical imaging performance and opening the door to numerous practical and technological applications. To date, no studies in the literature have provided in-depth analyses of the methods used to prepare RE-CDs, the characterization techniques used, the challenges, and a critical analysis of what could be improved in the synthesis by proposing practical solutions. To fill this gap, this review initially presents a detailed survey of CDs and RE separately. Subsequently, RE-CDs hybrid materials are addressed, as well as their obtainment, commonly used characterizations, and recent applications, from analyte detection to their functionality in medical nanodevices. Finally, criticisms and suggestions for future work are also discussed to inspire new research and discoveries about the technological potential of hybrid materials derived from the doping of RE-CDs.