Properties Adjustment And Applications Of Carbon Quantum Dots

This paper was committed to study preparation, properties, and applicationof N-doped carbon dots. The main research work is listed as follows:（1） N-doped carbon quantum dots have been synthesized through a one-potsolvothermal route for the frst time, employing CCl4as the carbon source andNaNH₂as dechlorination reagent and nitrogen source. The experimental resultsshowed that the emission wavelength of carbon dots could be effciently tunedthrough adjusting the N-doping concentration at a relatively low reactiontemperature. It provides a new idea for tuning the luminescence of carbon-basedmaterials through non-metal doping. The as-obtained N-doped carbon dotsshowed high quantum yield and excellent stability and could be directly appliedin the imaging of peritoneal macrophages of mice without furtherfunctionalization. The strong tunable multicolor emission, upconverted PLproperties, together with the facile synthesis method of these N-doped CDs,could facilitate fundamental studies and more practical applications.（2） NCQDs/rutile TiO₂hierarchical microspheres assembled by rutile TiO₂nanorods and NCQDs were first synthesized through a mild hydrothermal route.As a result, the pseudo-first-order reaction constant for the degradation ofrhodamine B （RhB） on NCQDs/TiO₂(0.11min^-1) is215.7,7.3and1.3timeslarger than that o f NCQDs (0.00051min^-1), TiO₂(0.015min^-1), andCQDs/TiO₂(0.086min^-1), respectively. The functions of NCQDs werediscussed and a new synergistic photosensitized mechanism was proposed forthe degradation of RhB on the as-synthesized NCQDs/TiO₂nanocompositesbased on the experimental results. NCQDs were also applied as metal-freesensitizers in dye-sensitized solar cells （DSSCs） for the first time. A preliminarystudy shows that under one sun illumination （AM1.5）, the open circuit voltage and fill factor values reach0.46V and43%, respectively, achieving a powerconversion efficiency of0.13%in the proof-of-concept TiO₂-based DSSCsdevice. The performance of NCQDs sensitized solar cells surpasses that ofN-free counterpart as well. N-doping lowered the work function of CQDs,which was responsible for enhanced photocatalytic activity of NCQDs/TiO₂andbetter TiO₂-based DSSCs performance.