阅读说明：本技术 一种co2电化学转化制石墨烯的方法 (CO (carbon monoxide)2Method for preparing graphene through electrochemical conversion ) 是由 任志博 张畅 余智勇 郜时旺 刘练波 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种CO<Sub>2</Sub>电化学转化制石墨烯的方法,包括以下步骤：1)向电解装置中通入CO<Sub>2</Sub>气体,其中,电解装置中的电解质为熔融碳酸盐,在电解装置中发生电化学解离反应,并在电解装置的阴极上生成碳纳米片,其中,所述碳纳米片包裹于阴极上；2)将包裹有碳纳米片的阴极作为剥离阳极插入剥离电解装置的电解液中,同时插入于剥离阴极,并接通剥离电源,在电场的作用下电解液中的离子进入到碳纳米片内部,内部水电解产生气体,以电化学剥离碳纳米片,获得石墨烯悬浊液；3)将石墨烯悬浊液进行离心分离,并洗涤去除可溶性杂质,得固体产物；4)将固体产物进行冷冻干燥脱除水分,得石墨烯,该方法能够制备得到石墨烯,且具有高效、绿色环保且成本低的特点。(The invention discloses CO 2 The method for preparing graphene through electrochemical conversion comprises the following steps: 1) introducing CO into the electrolysis device 2 Gas, wherein an electrolyte in the electrolysis device is molten carbonate, electrochemical dissociation reaction is carried out in the electrolysis device, and carbon nano sheets are generated on a cathode of the electrolysis device, wherein the carbon nano sheets are wrapped on the cathode; 2) inserting the cathode wrapped with the carbon nanosheets into electrolyte of a stripping electrolysis device as a stripping anode, simultaneously inserting the stripping cathode, switching on a stripping power supply, allowing ions in the electrolyte to enter the carbon nanosheets under the action of an electric field, electrolyzing the internal water to generate gas, and electrochemically stripping the carbon nanosheets to obtain a graphene suspension; 3) carrying out centrifugal separation on the graphene suspension, and washing to remove soluble impurities to obtain a solid product; 4) freeze drying the solid product to remove water to obtain graphene, and the method can prepare graphiteAlkene, and have high-efficient, green and characteristics with low costs.)

1. CO (carbon monoxide)₂The method for preparing graphene through electrochemical conversion is characterized by comprising the following steps:

1) introducing CO into the electrolysis device₂Gas, wherein the electrolyte in the electrolysis device is molten carbonate, and the electrolysis power supply is connected with the electrolysis device, and electrochemical decomposition occurs in the electrolysis devicePerforming dissociation reaction, and generating carbon nano sheets on a cathode of an electrolytic device, wherein the carbon nano sheets are wrapped on the cathode;

2) inserting the cathode wrapped with the carbon nanosheets into electrolyte of a stripping electrolysis device as a stripping anode, simultaneously inserting the stripping cathode, switching on a stripping power supply, allowing ions in the electrolyte to enter the carbon nanosheets under the action of an electric field in the stripping electrolysis device, electrolyzing the water in the interior to generate gas, and electrochemically stripping the carbon nanosheets to obtain a graphene suspension;

3) carrying out centrifugal separation on the graphene turbid liquid obtained in the step 2), and washing to remove soluble impurities to obtain a solid product;

4) and 3) carrying out freeze drying on the solid product obtained in the step 3) to remove moisture, so as to obtain the graphene.

2. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that in the step 1), the molten carbonate is Li₂CO₃、Na₂CO₃And K₂CO₃The reaction temperature in the electrochemical dissociation reaction process is 650-850 ℃.

3. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that a cathode in an electrolysis device is a stainless steel wire mesh, an anode in the electrolysis device is a stainless steel plate or a nickel-chromium-iron alloy plate, the surface of the stainless steel wire mesh is plated with Zn, Ni or Cr, the surface of the anode in the electrolysis device is plated with Pt or Ir, and the distance between the adjacent anode and the cathode in the electrolysis device is 1cm-3 cm.

4. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that the electrochemical dissociation reaction generated in the electrolysis device is of an intermittent operation type, and CO is continuously introduced in the reaction process₂A gas.

5. CO according to claim 1₂Electrochemical deviceThe method for preparing graphene by chemical conversion is characterized in that in the process of electrochemical dissociation reaction in an electrolysis device, the output current of an electrolysis power supply is divided into three continuous stages, wherein the current density of the first stage is 0.5A/m²-2A/m²The duration is 5min-15 min; the current density of the second section is 4A/m²-5A/m²The duration is 3min-6 min; the current density of the third section is 15A/m²-30A/m²The duration is 200min-400 min.

6. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that a stripping cathode is a stainless steel electrode plated with Pt, and the stripping cathode and the stripping anode are isolated through a regenerated cellulose-based dialysis membrane or a modified cellulose-based dialysis membrane.

7. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that the electrolyte in the stripping electrolysis device is (NH) with the concentration of 0.2-2 mol/L₄)₂SO₄Solution, Na₂SO₄Solutions or K₂SO₄And (3) solution.

8. CO according to claim 1₂The method for preparing graphene through electrochemical conversion is characterized in that the density of the output current of the stripping power supply is 10-20A/m²The duration is 6-12 h.

Technical Field

The invention belongs to electrochemical technology and CO₂The field of resource utilization, and relates to CO₂A method for preparing graphene through electrochemical conversion.

Background

With the increasing global warming effect, the survival and development of human beings are threatened by derived problems such as climate abnormity, frequent natural disasters, sea level rise and the like. CO2₂Is the most important greenhouse gas, and the key point for inhibiting the greenhouse effect is to control the emission of carbon dioxide. The thermal power plant using fossil fuel as main energy source is the largest centralized emission source, and CO in flue gas of the power plant₂Accounting for 37.5% of the total carbon emissions. For China, at present, electric power is still mainly supplied by coal-fired power plants, and the pressure of carbon emission reduction is huge. CO2₂The capture and sequestration utilization (CCUS) is an important technical choice for practicing the strategy of low carbon development in China. After years of development, domestic and foreign CO₂The trapping technology is developed and mature, and the commercialized CO of early development, project demonstration and commercialization is completed₂The trap has already started operating. However, CO₂The resource utilization technology development is relatively lagged and is still in the starting stage. Introducing CO₂The conversion into energy, chemical raw materials and fine chemicals with more additional values can obviously reduce the cost of the CCUS full process, so that the CCUS full process has wide application value. By using CO₂The technologies of methanol, formic acid, synthesis gas, methane and the like are proposed one after another, but the additional values of the products are not enough to obviously improve CO₂The utilization value of (2).

Due to the unique microstructure characteristics of the graphene, the graphene has excellent characteristics of high light transmittance, excellent electrical conductivity, high thermal conductivity, strong mechanical properties, large specific surface area and the like, and has wide application prospects in the fields of new energy, energy storage, electronic devices and the like. It is known that graphite sheets are bonded by weak van der waals force, and effective separation between the sheets can be realized by using a mechanical, physical or chemical method, and graphene products are obtained by stripping. So far, the preparation technology of graphene is still one of the bottlenecks restricting the wide application thereof, and has low cost and large batchThe technology for preparing high-quality and high-purity graphene needs to be continuously explored. The electrochemical stripping method is a novel method, has the advantages of rapidness, high efficiency, environmental protection, low cost and the like compared with the traditional method, and provides a new path for preparing the graphene. CO2₂The carbon material in various forms can be prepared by cracking, and the carbon material is further converted into graphene with high added value by an electrochemical stripping method, so that the method has important significance for the popularization of CCUS.

Therefore, there is a need in the art to develop a CO₂A system and a method for preparing graphene by electrochemical conversion take graphene with high added value as a target product, and CO is added₂Realizing deep resource utilization on the basis of trapping.

Disclosure of Invention

The object of the present invention is to overcome the disadvantages of the prior art mentioned above and to provide a CO₂The method for preparing the graphene through electrochemical conversion can be used for preparing the graphene and has the characteristics of high efficiency, environmental friendliness and low cost.

To achieve the above object, the CO of the present invention₂The method for preparing graphene through electrochemical conversion comprises the following steps:

1) introducing CO into the electrolysis device₂The gas, wherein the electrolyte in the electrolysis device is molten carbonate, an electrolysis power supply is connected with the electrolysis device, electrochemical dissociation reaction occurs in the electrolysis device, and carbon nano sheets are generated on a cathode of the electrolysis device, wherein the carbon nano sheets are wrapped on the cathode;

2) inserting the cathode wrapped with the carbon nanosheets into electrolyte of a stripping electrolysis device as a stripping anode, simultaneously inserting the stripping cathode, switching on a stripping power supply, allowing ions in the electrolyte to enter the carbon nanosheets under the action of an electric field in the stripping electrolysis device, electrolyzing the water in the interior to generate gas, and electrochemically stripping the carbon nanosheets to obtain a graphene suspension;

3) carrying out centrifugal separation on the graphene turbid liquid obtained in the step 2), and washing to remove soluble impurities to obtain a solid product;

4) and 3) carrying out freeze drying on the solid product obtained in the step 3) to remove moisture, so as to obtain the graphene.

In step 1), the molten carbonate is Li₂CO₃、Na₂CO₃And K₂CO₃The reaction temperature in the electrochemical dissociation reaction process is 650-850 ℃.

The cathode in the electrolysis device is a stainless steel wire mesh, the anode in the electrolysis device is a stainless steel plate or a nickel-chromium-iron alloy plate, the surface of the stainless steel wire mesh is plated with Zn, Ni or Cr, the surface of the anode in the electrolysis device is plated with Pt or Ir, and the distance between the adjacent anode and the cathode in the electrolysis device is 1cm-3 cm.

The electrochemical dissociation reaction in the electrolyzer is intermittent operation type, and CO is continuously introduced in the reaction process₂A gas.

In the process of electrochemical dissociation reaction in the electrolysis device, the output current of the electrolysis power supply is divided into three continuous stages, wherein the current density of the first stage is 0.5A/m²-2A/m²The duration is 5min-15 min; the current density of the second section is 4A/m²-5A/m²The duration is 3min-6 min; the current density of the third section is 15A/m²-30A/m²The duration is 200min-400 min.

The stripping cathode is a stainless steel electrode plated with Pt, and the stripping cathode and the stripping anode are separated by a regenerated cellulose-based dialysis membrane or a modified cellulose-based dialysis membrane.

The electrolyte in the stripping electrolysis device is (NH) with the concentration of 0.2mol/L-2mol/L₄)₂SO₄Solution, Na₂SO₄Solutions or K₂SO₄And (3) solution.

The density of the output current of the stripping power supply is 10-20A/m²The duration is 6-12 h.

The invention has the following beneficial effects:

CO according to the invention₂In the specific operation of the method for preparing graphene by electrochemical conversion, CO is adopted₂The preparation of graphene by combining electrochemical dissociation and electrochemical stripping technology specifically comprises introducing CO into an electrolysis device₂The method is characterized in that the electrolyte in the electrolytic device is molten carbonate, carbon nanosheets are generated on the cathode in an electrochemical dissociation mode, then the cathode wrapped with the carbon nanosheets is used as a stripping anode, and the graphene is prepared by electrochemical stripping.

Drawings

FIG. 1 is a schematic view of the structure of an electrolyzer;

FIG. 2 is a schematic view of the stripping electrolyzer.

Detailed Description

The present invention is described in further detail below with reference to examples:

referring to FIGS. 1 and 2, the CO of the present invention₂The method for preparing graphene through electrochemical conversion comprises the following steps:

1) introducing CO into the electrolysis device₂The gas, wherein the electrolyte in the electrolysis device is molten carbonate, an electrolysis power supply is connected with the electrolysis device, electrochemical dissociation reaction occurs in the electrolysis device, and carbon nano sheets are generated on a cathode of the electrolysis device, wherein the carbon nano sheets are wrapped on the cathode;

wherein the molten carbonate is Li₂CO₃、Na₂CO₃And K₂CO₃The reaction temperature in the electrochemical dissociation reaction process is 650-850 ℃; the cathode in the electrolysis device is a stainless steel wire mesh, the anode in the electrolysis device is a stainless steel plate or a nickel-chromium-iron alloy plate, the surface of the stainless steel wire mesh is plated with Zn, Ni or Cr, the surface of the anode in the electrolysis device is plated with Pt or Ir, and the distance between the adjacent anode and the cathode in the electrolysis device is 1cm-3 cm.

The electrochemical dissociation reaction in the electrolyzer is intermittent operation type, and CO is continuously introduced in the reaction process₂The output current of the electrolysis power supply is divided into three continuous stages in the process of electrochemical dissociation reaction in the gas and electrolysis deviceWherein the current density of the first stage is 0.5A/m²-2A/m²The duration is 5min-15 min; the current density of the second section is 4A/m²-5A/m²The duration is 3min-6 min; the current density of the third section is 15A/m²-30A/m²The duration is 200min-400 min.

CO₂During dissociation, taking Li2CO3 as an example, the reaction occurring at the cathode is:

LiCO₃+4e→LiO+C_nano-sheet+2O^2-

The reaction occurring at the anode was:

2O^2-→O₂+4e

continuously supplementing CO2 into electrolyte in the electrolytic device during the reaction:

LiO+CO₂→LiCO₃；

2) inserting the cathode wrapped with the carbon nanosheets into electrolyte of a stripping electrolysis device as a stripping anode, simultaneously inserting the stripping cathode, switching on a stripping power supply, allowing ions in the electrolyte to enter the carbon nanosheets under the action of an electric field in the stripping electrolysis device, electrolyzing the water in the interior to generate gas, and electrochemically stripping the carbon nanosheets to obtain a graphene suspension;

the stripping cathode is a stainless steel electrode plated with Pt, and the stripping cathode and the stripping anode are separated by a regenerated cellulose-based dialysis membrane or a modified cellulose-based dialysis membrane.

The electrolyte in the stripping electrolysis device is (NH) with the concentration of 0.2mol/L-2mol/L₄)₂SO₄Solution, Na₂SO₄Solutions or K₂SO₄And (3) solution.

The density of the output current of the stripping power supply is 10-20A/m²The duration is 6-12 h.

3) Carrying out centrifugal separation on the graphene turbid liquid obtained in the step 2), and washing to remove soluble impurities to obtain a solid product;

4) and 3) carrying out freeze drying on the solid product obtained in the step 3) to remove moisture, so as to obtain the graphene.