Green Carbon Dots from Sustainable Precursors: Advances in Photoluminescent Properties and Forensic Applications

Abstract

Carbon dots (CDs) have rapidly emerged as promising nanomaterials due to their photoluminescent properties, biocompatibility, and wide-ranging applications. This review critically evaluates the advancements in the green synthesis of CDs using plant-derived, animal-based, and waste materials such as neem, rosemary, eggshells, and cigarette butts. These eco-friendly routes offer a sustainable alternative to traditional chemical synthesis, aligning with the goals of green chemistry and waste valorisation. A thorough look at various synthesis methods—like hydrothermal, microwave-assisted, and combustion techniques—is included, focusing on how easy they are to scale up, how much energy they use, and their drawbacks.

The review also looks at how adding elements like N, S, P, and B can change fluorescence, improve sensing abilities, and make them more compatible with living things. The physicochemical and optical properties of CDs—such as size, crystallinity, quantum yield, and stability—are discussed using standard characterization tools.

Special attention is given to forensic applications, particularly in latent fingerprint detection and enhancement, where green CDs show excellent performance across varied surfaces under UV and visible light. Their potential integration with smart detection tools and AI systems represents a major advancement in forensic imaging. Other emerging uses, including bioimaging, anti-counterfeiting, and environmental sensing, are also outlined. Finally, the review identifies existing challenges and future directions for large-scale implementation and regulatory validation.