CN-121976203-A - Method and system for preparing graphene oxide based on dynamic gas-liquid interface and pulse electrochemistry

Abstract

The invention discloses a method and a system for preparing graphene oxide based on a dynamic gas-liquid interface and pulse electrochemistry. The method comprises the steps of taking an organic acid aqueous solution as electrolyte, adding a surfactant, taking graphite as an anode, arranging a microporous gas diffusion plate below the anode, introducing ozone-containing oxygen, simultaneously applying ultrasonic and mechanical stirring, and applying pulse voltage with specific parameters by adopting a pulse power supply for reaction. According to the invention, efficient local oxidation and physical stripping of ozone are realized through a dynamic gas-liquid interface, and mild, efficient and controllable stripping of graphite is realized by combining an intermittent oxidation/relaxation mode of a pulse electric field. The method thoroughly avoids the use of traditional strong acid and heavy metal oxidants, is green and safe, has few defects (low Raman ID/IG ratio), high single-layer rate and uniform size of the prepared graphene oxide, and can regulate and control the product structure through multidimensional parameters. The invention provides a new way for green controllable preparation of high-performance graphene oxide.

Inventors

• ZHU WENJIE
• QIN ZHIHONG
• YANG GANG
• LIU ZHAOPING
• ZHOU XUFENG

Assignees

• 宁波石墨烯创新中心有限公司

Dates

Publication Date

20260505

Application Date

20251230

Claims (10)

1. 1. The method for preparing graphene oxide based on dynamic gas-liquid interface and pulse electrochemistry is characterized by comprising the following steps: S1, preparing an electrolyte solution, namely dissolving organic acid in water to prepare an organic acid aqueous solution, then adding a surfactant into the organic acid aqueous solution, and stirring the mixture until the surfactant is completely dispersed and dissolved to form a uniform electrolyte; S2, assembling an electrochemical reaction system, namely taking graphite as an anode, taking an inert electrode as a cathode, and fixing the graphite in parallel in an electrolytic cell; s3, constructing a dynamic interface and carrying out pulse electrochemical stripping, namely continuously introducing an oxygen mixed gas containing ozone into the microporous gas diffusion plate, simultaneously starting an ultrasonic device acting on an electrolytic cell and the magnetic stirrer, and then applying pulse voltage to an electrode to carry out reaction until a graphite anode is completely stripped; and S4, post-processing the product, namely collecting suspension in the electrolytic cell after the reaction is finished, and cleaning to obtain pure graphene oxide.
2. 2. The method of claim 1, wherein in the step S1, the organic acid is one or more of oxalic acid, malonic acid, succinic acid, citric acid and tartaric acid, and the concentration of the prepared organic acid aqueous solution is 0.05-0.5 mol/L.
3. 3. The method according to claim 1, wherein in the step S1, the surfactant is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, polyethylene glycol octyl phenyl ether, polyoxyethylene ether and sulfobetaine, and the mass concentration of the surfactant in the electrolyte is 0.01% -0.1% based on the mass of water.
4. 4. The method according to claim 1, wherein in the step S1, the mass of the graphite is 0.1-1 g.
5. 5. The method according to claim 1, wherein in the step S3, the volume concentration of ozone in the ozone-containing oxygen mixed gas is 1% -10%.
6. 6. The method according to claim 1 or 5, wherein in step S3, the flow rate of the ozone-containing oxygen mixed gas is 20-100 mL/min.
7. 7. The method according to claim 1, wherein in the step S3, the power of the ultrasonic device is 50-200W, and the rotating speed of the magnetic stirrer is 100-300 rpm.
8. 8. The method according to claim 1, wherein in the step S3, the pulse voltage parameter satisfies that the high potential Eh is +2.5V to +5.0V (vs. cathode), the low potential El is 0V to +1.5V (vs. cathode), the pulse frequency f is 1-1000 Hz, and the duty ratio D is 10% -90%.
9. 9. A system for implementing the method of any one of claims 1-8, comprising: an electrolytic cell for containing an electrolyte solution and electrodes; an anode composed of a graphite material; A cathode composed of an inert material; The positive electrode and the negative electrode of the pulse power supply are respectively and electrically connected with the anode and the cathode; the microporous gas diffusion plate is arranged at the bottom of the electrolytic cell below the anode and is used for uniformly dispersing and introducing gas into the anode region; The gas source is used for providing an oxygen mixed gas containing ozone and is connected with the microporous gas diffusion plate through a pipeline; an ultrasonic device, the transducer of which is coupled with the electrolytic cell or is arranged in the electrolytic cell; the magnetic stirrer is arranged below the electrolytic cell.
10. 10. The system of claim 9, wherein the inert material of the cathode is platinum, gold, or carbon felt.

Description

Method and system for preparing graphene oxide based on dynamic gas-liquid interface and pulse electrochemistry Technical Field The invention relates to the technical field of two-dimensional nanomaterial preparation, in particular to an electrochemical preparation method of graphene oxide, and particularly relates to a method and a special system for realizing efficient and controllable stripping and oxidization of graphite by utilizing the synergistic effect of a dynamic gas-liquid interface and a pulse electrochemical technology. Background This section provides only background information related to the present application so as to enable those skilled in the art to more thoroughly and accurately understand the present application, and is not necessarily prior art. Graphene oxide has become a key base material in the fields of composite materials, energy storage, biomedicine, catalysis and the like due to the unique two-dimensional structure, rich surface functional groups and excellent solution dispersibility. The large-scale and high-quality preparation is a precondition for promoting the development of related applications. Currently, the traditional preparation of graphene oxide mainly depends on chemical oxidation methods such as Hummers method, brodie method and Staudenmaier method. These processes generally involve the use of strong acids (e.g. concentrated sulfuric acid, concentrated nitric acid) and strong oxidants (e.g. potassium permanganate, potassium chlorate) and have the inherent disadvantages of (1) violent and dangerous reactions with large amounts of heat and toxic gas emissions, significant explosion risks, and extremely demanding production equipment and safety control requirements. (2) The environmental pollution is serious, a large amount of waste water and waste residue containing heavy metals and strong acid are generated after the reaction, the treatment cost is high, and the environmental burden is heavy. (3) The product has a plurality of structural defects, namely, a great amount of irreversible structural defects (such as holes) can be introduced into the graphene substrate by the violent reaction of strong acid and strong oxidant, and the oxidation degree and the distribution of functional groups are difficult to control accurately. (4) The process flow is long, and the impurity ions are removed by repeated cleaning, centrifuging and dialyzing, so that the process is complicated and water and energy consumption are realized. To overcome the above drawbacks, electrochemical methods have been developed for preparing graphene oxide. The existing electrochemical method generally takes graphite as an anode or simultaneously takes the graphite as a cathode and anode, and performs intercalation, oxidation and stripping in a solution containing electrolyte. However, the existing electrochemical method has a plurality of limitations that (1) the efficiency and the oxidation degree are contradictory, namely the stripping efficiency is low at low voltage, and the efficiency is improved at high voltage but is easy to cause excessive oxidation and even complete degradation into micromolecular carbonaceous fragments, so that the integrity of a carbon skeleton is damaged. (2) Electrolyte limitations in that corrosive acids or high concentrations of salts are still often required to achieve adequate conductivity and intercalation, are not environmentally friendly and equipment friendly, and are complex as electrolysis byproducts. (3) The stripping products are uneven, in the traditional electrolytic cell, bubbles on the surface of the electrode are attached (such as oxygen evolution reaction) to cause uneven current distribution, so that the stripping degree is different, and the size distribution of the product is wide. (4) The graphene oxide structure (such as oxidation degree, layer number and size) is difficult to flexibly regulate and control according to application requirements. Therefore, a novel electrochemical preparation method which can give consideration to high efficiency, green and safety and realize accurate regulation and control on the microstructure of the graphene oxide is developed, and has important scientific and engineering values for promoting high-end application of the graphene oxide. Disclosure of Invention The invention aims to provide a novel green, safe and efficient electrochemical preparation method of graphene oxide, aiming at the problems of environmental pollution, poor safety, multiple product defects, uncontrollable structure and the like existing in the existing chemical oxidation method and the traditional electrochemical method for preparing graphene oxide. It is another object of the present invention to provide a dedicated system for carrying out the above method which is capable of constructing a unique dynamic gas-liquid interface reaction environment. In order to achieve the aim of the invention, the invention adopts the following technical sch