A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 μM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling.

MXene‐derived quantum dots (MQDs) have begun to attract much attention recently, but their most attractive features (i.e., optical properties) are still explored less than expected. In the present work, Ti3C2Tx MQDs with solvent‐determined optical characteristics and size distributions are prepared through solvothermal treatment of Ti3C2Tx nanosheets in various solvents. White‐emitting photoluminescence (PL) under 365 nm UV irradiation is obtained in dimethyl sulfoxide (DMSO), while blue in dimethylformamide (DMF) and ethanol, respectively. Moreover, the average diameters and quantum yields of the MQDs are 3.3 ± 0.2 nm and 10.7%; 2.5 ± 0.2 nm and 6.9%; as well as 1.8 ± 0.1 nm and 4.1% in DMF, ethanol, and DMSO, respectively. Interestingly, among a variety of metal ions, Fe3+ shows specific quenching effect toward the PL of the MQDs in DMF rather than in the other two. Moreover, electrochemiluminescence of the MQDs is observed using persulfate as coreactant for the first time. The possible mechanisms are discussed based on the combined influences of polarity, oxidation effect, and boiling point of the different solvents and the various characterizations.

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