Observing Carbon Dots in Putative Boron Nitride Quantum\nDots

Boron\nnitride quantum dots (BNQDs) have garnered a significant\namount of attention in recent years due to their attractive optical\nproperties, high stability, low toxicity, and good biocompatibility.\nHowever, our study reveals a critical mischaracterization in this\nfield, demonstrating that some so-called BNQDs are, in fact, carbon\ndots (CDs) formed through the unintended carbonization of organic\nsolvents during synthesis. Herein, we investigate the widely used\ncombination of sonication and solvothermal conversion for BNQD preparation,\nusing ethanol and <i>N</i>-methyl-2-pyrrolidone as solvents.\nParallel syntheses are performed with and without BN bulk to produce\nthe putative BNQDs and their corresponding CDs, respectively. Comprehensive\ncharacterizations, including optical properties and chemical compositions,\nreveal striking similarities between the BNQDs and the corresponding\nCDs. These similarities indicate that the presumed BNQDs are essentially\nCDs. This finding challenges the validity of numerous studies on BNQDs\nand calls for a critical re-evaluation of the synthesis–structure–property\nrelationship in BN-based nanomaterials.