Highly Facile Strategy for the Ultrasensitive Differentiation of D₂O and H₂O by Red-Emitting Carbon Dots

Distinguishing between D₂O and H₂O is crucial for the utilization of high-purity D₂O in the nuclear industry, chemical analysis, biological pathway tracing, and other fields, as well as for ensuring the integrity of water quality and safeguarding human health, but challenging due to their highly analogous physical and chemical properties. On the basis of the fact that D₂O exhibits superior hydrogen bond strength and deprotonation capacity for phenolic OH group compared to H₂O, the red-emitting carbon dots (RCDs) with excellent optical properties, salt tolerance, photobleaching resistance, long-term storage stability, and biocompatibility were synthesized via a one-step strategy at room temperature. The RCDs demonstrated sensitivity for detecting D₂O content in H₂O and H₂O content in D₂O was found to be 0.060% and 0.15%, respectively. Collectively, this research expanded the potential applications of carbon nanomaterials and introduced a highly facile strategy for analyzing the isotopic purity of D₂O.