The industrial mass production of graphene is not a problem today.

In fact, graphite oxide reduction method, micromechanical exfoliation method, chemical vapor deposition method, epitaxial growth and other methods have been able to achieve a certain degree of mass production.

However, the graphene produced by these methods is not of high quality on the one hand, and the graphene produced by these methods is highly polluted on the other hand.

For example, in the graphene oxide reduction method, the prepared graphene needs to be reduced at high temperature, and in this process, incomplete reduction will lead to the coexistence of graphene and graphene oxide, and will also lead to the doping of other impurities in graphene.

And if you use a vacuum furnace for restoration, the cost is too high.

As a result, this method can only produce some low-quality graphene at present.

This type of graphene can not be used in high-performance electronic devices, energy storage, medicine and other fields, generally speaking, this kind of graphene doped with impurities and pollution, mainly in construction, adsorbents, desalination, composite materials and other basic fields.

However, the demand for graphene in these fields is actually not large, after all, even if graphene is of low quality, it is still graphene, and the price is much more expensive than the technology and materials used in the original industry.

High-quality graphene is the field with high demand.

Whether it is electronics, photosensitive devices or aerospace and other fields, there has always been a gap for high-quality graphene.

However, the industrial mass production of high-quality graphene is an extremely difficult field to solve.

No way, the high-quality graphene production process is too complicated.

To first manufacture high-quality graphene, it is necessary to prepare high-quality single-layer graphene first.

At present, high-quality single-layer graphene is almost limited by the cavity size of CVD equipment, and the existing CVD methods cannot realize the continuous preparation of single-layer graphene.

Although a country that has begun to secretly discharge nuclear sewage into the sea has demonstrated the 'so-called' 100-meter-long graphene in this field, the surface of the material is full of holes and is completely unusable.

Moreover, the continuous preparation technology of CVD graphene and the product yield problem have not been solved at present.

Secondly, the high-quality graphene transfer method is a difficult problem to solve, and the commonly used wet etching transfer often brings problems such as wrinkles, impurities, and damage, and it is difficult to achieve large-scale transfer.

Finally, it's a combination of the first two.

That is, the continuous preparation and transfer of CVD graphene are realized, and the two are matched and docked to form an automated production technology.

When the first two difficulties are not solved, there is no way out of high-quality graphene manufacturing.

In fact, how to evaluate a new technology, especially the technology of materials science, is not easy in itself.

It requires a lot of supporting conditions.

In fact, many materials science and technology achievements need to spend half of their energy on pure application testing later.

And this studio needs a lot of investment, and it is basically useless without sufficient capital support and downstream application support.

Although graphene is supported by downstream manufacturers, its manufacturing and application is a very difficult problem.

Therefore, Xu Chuancai is very interested in the mass production of high-quality graphene researched by the Chuanhai Materials Research Institute.

"Go to my office and say, the results of the experiment here will not be available until about three o'clock in the afternoon, but I have roughly sorted out the relevant production methods and steps yesterday."

Fan Pengyue took off his experimental gloves and took Xu Chuan to his office.

Turn on the computer, unlock it, he pulled up a data file from the computer, clicked on it and said: "The data hasn't had time to print out yet, you will use the computer to see it first." ”

Xu Chuan didn't care, took the position and sat down, carefully flipping through the information in front of him.

From the data point of view, this method of preparing high-quality graphene is expanded from the method of recovering graphene from the LIBs battery accidentally discovered in the second half of 19.

In 19 years, a researcher named 'Yan Liu' in the lithium-sulfur battery laboratory of the research institute used hydrazine hydrate, molten salt hydroxide, cathode waste current collector aluminum foil and other materials as reducing agents when further optimizing lithium batteries, trying to modify the LiFePO4 cathode and improve the electrochemical performance and cycling stability of lithium batteries.

However, the expected optimization was not achieved, but unexpectedly, when the product failed in the experiment, Yan Liu found a layer of carbon film attached to the negative electrode.

After testing, it was confirmed that this is a layer of graphene film material with high purity.

In this new chemical synthesis method, the graphite anode is chemically oxidized after electrochemical cycle to obtain uniformly dispersed graphene oxide.

Then, through the use of oxidants and reducing agents, graphene oxide is reduced to graphene.

The graphene synthesized in this way has high purity, and it is relatively pure and pollution-free.

Of course, it also has its drawbacks.

For example, the reduction of graphene oxide will involve the use of environmentally unfriendly and expensive oxidants and reducing agents, and at the same time, chemical reactions will also destroy the integrity of the structure of graphene film materials.

In addition, the transfer of graphene is also extremely difficult.

There are many shortcomings, but it is still a direction worth exploring.

This incident attracted Xu Chuan's attention at that time, but at that time, because he was busy with the controllable nuclear fusion project, he couldn't find time for in-depth research, so he could only hand over this matter to the Chuanhai Materials Research Institute himself.

More than a year and a half have passed, and combined with the institute's computational material model, this method of synthesizing high-purity graphene thin film materials has been greatly improved.

As we all know, there are three difficulties in the synthesis of high-quality graphene.

From the continuous synthesis of high-purity single-atom layer graphene layers, to the transfer of thin films, and the continuous industrialization are extremely difficult things.

After a year and a half of exploration, the materials laboratory has improved this new electrochemical synthesis method.

The first is to optimize the high purity of graphene, the anode material of the original LiFePO4 battery.

High-purity synthetic graphite with a purity of more than 99.999 percent is used to replace the original battery anode graphite material.

After all, although graphite is used for the negative electrode of LiFePO4 batteries, in order to improve the performance of the battery, it is not high-purity graphite, and there are impurities.

Although the number of these impurities is not large, they will also affect the quality of graphene in the process of synthesizing graphene.

Of course, that's not the point.

The key problem with this electrochemical synthesis of graphene is the need for redox and the transfer of synthetic graphene.

The latter is easy to solve, whether it is microwave transfer from the outside world, or liquid phase stripping method can be realized, but the efficiency is not high, and there will be problems such as defective products.

The former, for the reduction of graphene oxide, has always been a problem in the industry.

Although there are many options for reducing agents for graphene oxide, from hydrazine and hydrazine derivatives, to metal hydrides such as sodium borohydride, strong acids, strong bases, alcohols, phenols, vitamin C, reducing sugars (glucose, chitosan, etc.).

But either one has its own shortcomings.

For example, the use of some acid-reduced graphene will lead to the agglomeration and accumulation of the single-layer graphene structure due to the π-π interaction, resulting in a decrease in specific surface area, an increase in resistance, and a significant reduction in performance.

This limits its application prospects.

Or use hydrazine or hydrazine derivatives for reduction, although the obtained graphene solves the agglomeration phenomenon of the product, but also makes the reduced graphene introduce C-N bonds, causing pollution.

Moreover, hydrazine hydrate used is very toxic and is not suitable for use in large-scale production, industry, and biomedicine.

Therefore, Xu Chuan is very curious about how the Chuanhai Materials Research Institute solves this problem.

Following the documents, Xu Chuan continued to look down.

In the summary of the reduction method of graphene oxide, he saw the way in which graphene oxide was reduced by the Chuanhai Materials Research Institute.

Graphene oxide is modified on a specific electrode substrate by different thin film assembly methods to obtain a graphene oxide-modified electrode, and then the modified electrode is used as the working electrode of the classical three-electrode electrolysis system to undergo electrolytic reaction in a specific electrolyte solution, so as to reduce the graphene oxide film."

"Electrochemical reduction?"

Seeing this way, Xu Chuan was stunned for a moment.

He originally thought that the laboratory had found a new type of reducing agent, but he didn't expect that they would directly break away from the limitations of reducing agents and use alternative electrochemical methods.

[Graphene oxide was sonicated in deionized water for 1h, then modified on a conductive glass substrate, and electrochemically reacted with Hg/Hg2SO4 and Pt electrodes as reference electrodes and comparison electrodes in a standard three-electrode battery with Hg/Hg2SO4 electrodes as reference electrodes and contrast electrodes by extended cyclic voltammetry (CV, -1.0~1.0 V, relative to reversible hydrogen electrodes) in 0.1 mol/L Na2SO4 solution. 】

[X-ray photoelectron spectroscopy (XPS) was used to detect and control the reduction peak and specific capacitance values at -0.75 V.] 】

[Further combined with the electrochemical deposition method, graphene oxide was modified on a conductive glass substrate, and then paired with a glassy carbon electrode in a 0.1 mol/L solution for 0~-0.1 V intensity scanning, and a thin film located on the substrate was obtained.] 】

【. 】

The information is not very detailed, and there is not even any of those electron microscope structure diagrams, but it is enough for Xu Chuan to understand how they did it.

I have to say, this is a very ingenious way to find a different way.

Nowadays, the material industry has been considering the reduction of graphene oxide and the preparation of graphene by reducing agents or catalysts.

Although microwave reduction, hydrothermal reduction, catalytic reduction and other methods have been studied, these are not actually free from the limitations of reducing agents and catalysts.

This method of electrochemical reduction directly bypasses the influence of reducing agent and catalyst.

Not to mention its efficiency, but without the additives of reducing agents and catalysts, the purity of the reduced graphene is undoubtedly quite high.

After all, in the process of reduction, he has no influence from other foreign additives.

PS: There is another chapter in the evening, asking for a monthly pass. It's the end of the month, vote for the monthly tickets in the hands of the bigwigs! ~o(=∩ω∩=)m meow!

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