Preparation Of Carbon Dots/tungsten Disulfide Quantum Dots By Solvothermal Method And Its Application

Zero-dimensional nanomaterials have extremely high specific surface area,excellent thermal stability and good optical properties.Fluorescent carbon dots(CDs)are a new kind of zero-dimensional carbon nanomaterials with excellent optical properties and broad application prospects.It is worth noting that obtaining high-efficiency long-wavelength multicolor emission CDs and even solid-state fluorescent CDs is still a huge challenge.In this paper,CDs are functionalized by heteroatom doping and surface modification strategies,the fluorescence properties and luminescence mechanism of CDs are studied,and they are applied to the field of analysis and detection and optoelectronic devices.In addition,the new zero-dimensional nanomaterial tungsten disulfide quantum dots(WS₂ QDs)and MnO₂ nanosheets were combined to construct a ratio-type fluorescent probe for GSH detection.The main research contents are as follows:1.Using citric acid and Nile Blue A as precursors,the band gap is systematically controlled by simply changing the solvent in the reaction,thereby successfully obtaining bright three-color fluorescence emission CDs(B-,Y-and RCDs).The selected precursors and different solvents are the key to the formation of three emission CDs.Detailed characterization and density functional theory(DFT)calculations further indicate that the difference in emission color of CDs is related to the size of the sp² conjugated domain.In addition,both BCDs and YCDs have high selectivity and sensitivity to Sudan Red I.Multicolor emitting phosphors,fluorescent films,monochromatic LEDs and WLEDs are also obtained by mixing CDs with other substrates.2.Through the hydrothermal method using phthalic acid and ethylenediamine as precursors,solid fluorescent carbon dots(B-CDs and YG-CDs)with anti-self-quenching properties were obtained at 160°C and 240°C,respectively.The study found that the content of sp² domains in the two CDs is less,which can reduce the?-?interaction between the carbon nuclei,thereby inhibiting the quenching caused by aggregation and promoting solid-state fluorescence.A possible factor affecting the solid-state redshift is the increase in surface defects related to nitrogen.In addition,the red-shifted fluorescence of YG-CDs from aqueous solution to solid state is attributed to resonance energy transfer(RET)or reabsorption.Importantly,B-CDs and YG-CDs powders are further used to manufacture monochromatic LEDs and WLEDs.3.CDs-ABT is obtained by covalently linking carboxyl CDs and benzothiazole derivatives(ABT)through a simple amidation reaction.Studies have found that berberine hydrochloride(BRH)can significantly quench the fluorescence of CDs-ABT through the internal filtration effect(IFE).There is an excellent linear correlation between the BRH concentration in the range of 10–130?M and the fluorescence quenching of CDs-ABT,and the detection limit is as low as 3.5 n M.CDs-ABT-based fluorescence method has been applied to the detection of BRH in actual drug samples and urine.4.Using WS₂ QDs as the fluorescence signal and MnO₂ nanosheets as the second-order scattering(SOS)signal,the combination of fluorescence and scattered light was used to construct a ratiometric sensing platform for GSH detection.After adding MnO₂ nanosheets to the WS₂ QDs solution,IFE caused the fluorescence of WS₂ QDs to gradually weaken,while the SOS of the system gradually increased.After adding GSH to WS₂ QDs-MnO₂,MnO₂ nanosheets are reduced to Mn²⁺,and the weakening of IFE leads to the recovery of fluorescence of WS₂ QDs,and the SOS of the system decreases.Under the best experimental conditions,the value of F₄₀₆/S₆₄₈has a good linear relationship with the GSH concentration in the range of 0–60?M,and the detection limit is 0.12?M.In addition,the system is also used to detect GSH in real water samples and human serum.