Size Controlled Synthesis Of Nitrogen Doped Carbon Quantum Dots And Its Applicatios

Carbon quantum dots(CDs) have become a research focus in the field of nanomaterials due to its good water solubility, superior fluorescence properties, excellent photostability, tunable emission wavelength, low toxicity and favorable biocompatibility. However, the difficult synthetic steps such as harsh reaction conditions, cumbersome procedures and difficulties in size control limitted the development and application of CDs. In the current work, the size tunable nitrogen doped carbon quantum dots(N-CDs) were synthesized by a simple solvothermal approach. The compositions, structures and fluorescent performances were investigated by the corresponding characterizations. In addition, the as-prepared N-CDs could also be applied in the field of cell imaging and photocatalysis. The main results are following:1. The synthesis of size tunable N-CDs and the fluorescence properties: The size tunable N-CDs were successfully fabricated by a facile one-step solvothermal method with triisopropanolamine(TIPA) as the carbon source and nitrogen source. The N-CDs possessed an essentially crystalline nature which exhibitted excellent down- and up-conversion photoluminescence(PL) properties and even could convert NIR light(650~1000 nm) to visible light. The particle sizes of N-doped CDs were successfuly controlled by changing the nitric acid amount. It revealed that the higher amount of nitric acid could contributed to a slightly larger particle size and a relatively wider size distribution.2. The application of N-CDs in cell imaging: N-CDs were applied to bioimaging of Hela cells. The cytotoxicity of N-CDs was measured by MTT method. The results showed that the N-CDs had low cytotoxicity and the cell survival rate is up to 80% even treated with N-CDs at ultrahigh concentrations of 400 μg/mL. Cell imaging experiments showed that the whole cells had been successfully marked by N-CDs. The bright green and red fluorescence could be observed under the monochromater light of 488 nm and 543 nm irradiation, respectively.3. Preparation and properties of N-CDs/BiOBr composite photocatalyst: NCDs/BiOBr composites were synthesized by a one-step solventthermal method with ethanol as the solvent and TIPA as the carbon source and surfactant. The light reponse range and photocatalytic performance on MO of N-CDs/Bi OBr have been enhanced after the introduction of N-CDs. The photocatalytic activity of NCDs/BiOBr was higher than BiOBr 1.75 times on MO degradation with the molar ratio of TIPA and BiOBr of 2:1. The enhanced photocatalytic performance could ascribed to the strong light absorption capacity and large specific surface area.