Study On The Assembly Of Carbon Quantum Dots And Its Composite With Zinc Phthalocyanine

Carbon quantum dots(CQDs) as an impotant new class of carbon nanomaterials. Theyare attracting considerable attention as good water solubility and chemical inertness,particularly for their non-toxic, and favorable biocompatibility. Carbon quantum dotsdispersed in the liquid media showed excellent flurescence emission properties, but effort toexract CQDs from the solution phase typically result in the disruption of their surface stateand the fluorescence quenching, thus will limit its application in solid functional devices. Onthe other hand, carbon quantum dots are usually has strong absorption in the ultraviolet band,and the weak absorption in the visible regin, which led to the utilization of the sunlight is nothigh. In order to solve the problems above, this dissertation has undertaken the followingstudies:1,The amine-functionalized carbon quantum dots (N-CQDs) were synthesized by thesolvent-thermal method. The rod-like structure of solid carbon quantum dots were preparedby the Schiff bases reaction of N,N-dimethylformamide (DMF) and N-CQDs. Fluorescencespectrophotometer, UV spectrophotometer, transmission electron microscopy (TEM) andscanning electron microscopy (SEM) were used to characterize the fluorescence, morphologyand structure of the solid carbon nano-powders. The results indicated that: the formation ofsolid carbon quantum dot powders which exhibit Photoluminescence (PL) properties, similarto their solution based counterparts. The Schiff base formation on the surface of N-CQDscould protect the individual PL properties of N-CQDs during their self-assembly. Furthermore,the solid carbon quantum dot powders can be re-dispersed into aqueous solution with theDMF and the N-CQDs.2,The amine-functionalized carbon quantum dots (N-CQDs) and Zinc phthalocyaine(PcZn) were combined by electrostatic bonding under the mechanical stirring, resulting in anew composite, i.e. N-CQDs/PcZn. The photoinduced excited electron transfer via theinterface between N-CQDs and PcZn was determined through Fluorescence spectra, UV-Vis absorption spectra, Infrared spectra and Cyclic voltammetry. The excited electrons weretransferred on the PcZn molecules and then relaxed by radiative recombination, causing theenhanced fluorescence emission from PcZn. On the other hand, the separation ofelectron-hole pair was realized on N-CQDs and thus limited the possibility of radiativecombination on N-CQDs. Therefore, the composite of N-CQDs/PcZn showed a highphotocatalytic activity. Moreover, the stability and the photon conversion ability fromN-CQDs/PcZn composites depended on the reaction temperature. Our experimental resultssuggested that the room temperature was the optimum to obtain their good performance.3, The chlorine-functionalized carbon quantum dots (Cl-CQDs) were synthesized by thesolvent-thermal method. Cl-CQDs and Zinc phthalocyaine (PcZn) were combined byelectrostatic bonding under the mechanical stirring, resulting in a new composite, i.e.Cl-CQDs/PcZn. The photocatalytic activity of Cl-CQDs/PcZn was investigated and the resultsillustrate that the surface states chlorine of carbon quantum dots can catalyze degradation ofzine phthalocyanine.