CN113086973A

CN113086973A - Method for preparing graphene quantum dots by taking citric acid as raw material

Info

Publication number: CN113086973A
Application number: CN202110293234.XA
Authority: CN
Inventors: 阮红; 李裕琪; 梁建林; 庞斌友; 刘豪杰; 周立
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2021-07-09

Abstract

The invention discloses a method for preparing graphene quantum dots by taking citric acid as a raw material. Firstly, citric acid is taken as a carbon source, a certain amount of citric acid is uniformly dispersed in ionic liquid, a proper amount of deionized water is added into a mixed solution for ultrasonic dispersion, then the mixed solution is transferred into a reaction kettle with a polytetrafluoroethylene lining, the reaction kettle is heated in a drying oven, the mixed solution after the reaction is poured out, and the required graphene quantum dots can be obtained through centrifugation and dialysis treatment. The influence of factors such as the proportion of reaction raw materials and the reaction time on the performance of the graphene quantum dots is researched. The method is simple to operate and easy to popularize and apply on a large scale, and the prepared graphene quantum dots are uniform in size, good in water solubility and stable in fluorescence property.

Description

Method for preparing graphene quantum dots by taking citric acid as raw material

Technical Field

The invention belongs to the technical field of novel graphene materials, and relates to a method for preparing graphene quantum dots by taking citric acid as a raw material.

Background

The graphene quantum dots are carbon-based zero-dimensional materials. Compared with traditional fluorescent materials such as organic fluorescent dye, semiconductor quantum dots and rare earth fluorescent nanoparticles, the graphene quantum dots have a plurality of excellent performances such as good water solubility, biocompatibility, low toxicity, low cost, environmental friendliness, wide raw material sources and the like. The graphene quantum dots are generally synthesized by a laser ablation method, a chemical oxidation method, a combustion method, an electrochemical synthesis method, an arc discharge method, a hydrothermal synthesis method, a microwave synthesis method and other preparation processes. Due to the excellent performance and the simple preparation method, the graphene quantum dots have good application prospects in various fields such as medical imaging technology, biological detection and sensors, environmental monitoring, chemical analysis, catalysis, energy development and the like.

In 2004, Xu et al reported a method for preparing single-walled carbon nanotubes (SWCNTs) using arc discharge, and discovered for the first time graphene quantum dots that can emit bright fluorescence during the process of purifying the product by electrophoresis. Zhu et al prepare graphene quantum by taking graphite oxide as a raw material and a hydrothermal method. Shen et al developed graphene quanta with surfaces passivated by polyethylene glycol, and observed up-conversion fluorescence imaging under a 808nm fluorescence microscope. Testsuka et al reported a simple chemical process for the preparation of GQDs rich in amino groups on their surface.

With the more intensive research on graphene quantum dots, people make great progress on the synthesis, performance and application aspects of the graphene quantum dots. Meanwhile, the graphene quantum dots are wide in raw material source and low in preparation cost, have great advantages in the field of material preparation, and have good application prospects in wide fields of medical imaging equipment, tiny light-emitting diodes, chemical sensors, photocatalytic reactions and the like. But its greatest limitation is the low autofluorescence quantum yield (< 10%). In addition, an effective functional modification and fluorescence regulation mode is lacked, the light-emitting mechanism is still unclear so far, and the factors limit the development of the graphene quantum dots to different degrees. Therefore, how to obtain graphene quantum dots with high quality, high fluorescence efficiency and adjustable fluorescence, and simultaneously reveal the fluorescence emission mechanism thereof, remains an important and urgent subject for the scientists of chemistry and materials.

According to the method, citric acid is used as a carbon source, and the graphene quantum dots are prepared by a hydrothermal method, so that the method has the advantages of low cost, convenience in operation, simple equipment used, easiness in industrial production and the like. The influence of factors such as raw material ratio and heating time on various performances of the graphene quantum dots is intensively researched. The graphene quantum dots prepared by the method have uniform size, good water solubility and stable fluorescence property, and a simple method is provided for preparing high-quality graphene quantum dots by taking citric acid as a raw material.

Disclosure of Invention

The invention aims to provide a method for preparing graphene quantum dots by taking citric acid as a raw material.

The method comprises the following specific steps:

(1) 0.768g of citric acid solution is uniformly dispersed in 0-26.388g of ionic liquid.

(2) And (2) adding 10ml of deionized water into the dispersion liquid obtained in the step (1), carrying out ultrasonic treatment for 15-30min, and transferring the mixture into a reaction kettle with a polytetrafluoroethylene lining.

(3) And (3) placing the reaction kettle in an oven, and reacting for 3-24 h at 110 ℃.

(4) Pouring out the mixed solution after the reaction in the step (3), and centrifuging and dialyzing at 9000-12000rpm to obtain the graphene quantum dots.

The method is simple to operate, and the prepared graphene quantum dots are uniform in size, good in water solubility and stable in fluorescence property.

Drawings

Fig. 1 is a graph of the ultraviolet-visible absorption spectrum of the graphene quantum dot prepared in example 2.

Fig. 2 is a fluorescence spectrum of the graphene quantum dot prepared in example 2 under different excitation wavelengths.

Detailed Description

Example 1:

(1) 0.768g of citric acid is uniformly dispersed in 10ml of deionized water, and the mixture is transferred into a reaction kettle with a polytetrafluoroethylene lining after being subjected to ultrasonic dispersion for 15 min.

(2) The reaction kettle is placed in an oven and reacts for 12 hours at the temperature of 110 ℃.

(3) Pouring out the mixed solution after the reaction in the step (2), and centrifuging and dialyzing at 9000rpm to obtain the graphene quantum dots.

Example 2:

(1) 0.768g of citric acid was homogeneously dispersed in 0.8796g of ionic liquid.

(2) And (2) adding 10ml of deionized water into the dispersion liquid obtained in the step (1), carrying out ultrasonic dispersion for 15min, and transferring to a reaction kettle with a polytetrafluoroethylene lining.

(3) The reaction kettle is placed in an oven and reacts for 12 hours at the temperature of 110 ℃.

(4) Pouring out the mixed solution after the reaction in the step (3), and centrifuging and dialyzing at 9000rpm to obtain the graphene quantum dots.

Example 3:

(1) 0.768g of citric acid was homogeneously dispersed in 8.796g of ionic liquid.

Example 4:

(1) 0.768g of citric acid was uniformly dispersed in 26.388g of ionic liquid.

Example 5:

(1) 0.8796g of ionic liquid is dispersed in 10ml of deionized water, and the mixture is transferred to a reaction kettle with a polytetrafluoroethylene lining after being subjected to ultrasonic treatment for 15 min.

(3) Pouring out the mixed liquid after the reaction in the step (2), centrifuging at 9000rpm, and dialyzing to obtain the graphene quantum dots.

Example 6:

(2) And (2) ultrasonically dispersing the dispersion liquid obtained in the step (1) for 15min, and then transferring the dispersion liquid into a reaction kettle with a polytetrafluoroethylene lining.

(3) The reaction kettle is placed in an oven and reacts for 3 hours at the temperature of 110 ℃.

(4) Pouring out the mixed solution after the reaction in the step (3), and centrifuging at 9000rpm, dialyzing and filtering to obtain the graphene quantum dots.

Example 7:

(3) The reaction kettle is placed in an oven and reacts for 24 hours at the temperature of 110 ℃.

Claims

1. A method for preparing graphene quantum dots by taking citric acid as a raw material is characterized by comprising the following steps:

step one, dispersing citric acid with certain mass in 0-26.388g of ionic liquid at room temperature;

step two, adding 10-30ml of deionized water into the dispersion liquid obtained in the step one, performing ultrasonic dispersion for 10-30min, and transferring the dispersion liquid into a reaction kettle;

step three, placing the reaction kettle in an oven, and controlling the oven to react for 3-24 h at 100-180 ℃;

and step four, pouring out the mixed solution obtained after the reaction in the step three, centrifuging at 10000-20000 rpm, transferring into a dialysis bag, and dialyzing for 3-10 days to obtain the graphene quantum dots.