Carbon Dots Derived from Citric Acid as the Primary Carbon Source: Synthesis, Optical Properties, and Applications

Carbon dots (CDs) derived from citric acid (CA) as the primary carbon source have garnered significant attention in various research fields in recent years, attributed to their remarkable biocompatibility, negligible toxicity, low cost, environmental friendliness, abundant functional groups, high stability, and excellent tunable photoluminescence (PL) characteristics. In this review, we systematically summarize the synthesis methods of CDs using CA as the primary carbon source and provide a detailed elaboration of their optical properties, encompassing ultraviolet-visible (UV-vis) absorption, fluorescence (FL), delayed fluorescence (DF), and room-temperature phosphorescence (RTP). Furthermore, we introduce the diverse optical applications of this category of CDs, such as sensing, information encryption, light-emitting diodes (LEDs), bioimaging, and anti-tumor therapy. Ultimately, we discuss the challenges encountered by CDs derived from CA as the primary carbon source, future research directions, and the development prospects of this field.