Abstract Graphene is a new type of material that has been valued by all countries in recent years. It has a variety of special physical properties and has broad application prospects in the military and civilian fields. However, large-scale industrial preparation of graphene has been a worldwide problem. Recently, the Polymer Science Laboratory of Zhejiang University has achieved this aspect...
Graphene is a new type of material that has been valued by countries in recent years. It has a variety of special physical properties and has broad application prospects in the military and civilian fields. However, large-scale industrial preparation of graphene has been a worldwide problem. Recently, the Polymer Science Laboratory of Zhejiang University has made an important breakthrough in this respect. By using a new type of iron-based oxidant instead of the traditional oxidant, a new technology for preparing graphene with fast, low-cost and pollution-free is realized, and it is expected to solve this material. Large-scale industrial production problems. It is reported that the prospects of graphene in the fields of electronics and optics are extremely broad. "Production experiment data shows that such a single layer of graphene oxide can be produced within one hour by a new method, and it is expected to be applied in large scale in the industrial field in the future." Recently, the polymer department at Zhejiang University was full. In the laboratory of bottles and cans, Professor Gao Chao of the department showed reporters a brown powder similar to coffee powder, and told reporters.
"Natural-Communication" magazine recently published a research report on the preparation of graphene completed by the superb research group. This achievement avoids many defects of the existing graphene preparation method, breaks through the traditional method of preparing graphene oxide, and finds a "green" route for preparing single-layer graphene at low cost.
Graphene is a "honeycomb" sheet resembling a regular hexagon composed of a single layer of carbon atoms. "200,000 pieces of graphene are added together, which is equivalent to the thickness of a human hair." Gao Chao told reporters that the two-dimensional structure of carbon has always existed in scientists' conjectures, but it has been difficult to achieve. The key challenge is how to layer graphite into extremely thin sheets.
In 2004, Heim and Novoselov of the University of Manchester in the United Kingdom finally produced graphene with a thickness of only 0.335 nm. This is the first time in the world to obtain single-layer graphene, and the two have obtained Nobel Physics in 2010. Scholarship. At present, the mechanical peeling method evolved from the tape paper sticking method proposed by the two has become a common method for preparing graphene in the laboratory. However, the limitations of this method are very obvious, and a graphene mixture of different layers is produced, making it difficult to prepare a single layer of graphene on a large scale.
In the view of Gao Chao, if graphene is to be truly applied, there are three key issues that need to be addressed: raw materials, materials and devices. The raw material is graphene, especially single-layer graphene; the material is a macroscopic material assembled from graphene raw materials; the device is to make the material into functional equipment. “The macro material problem has been basically solved, and the most fundamental raw material problem is still under exploration,†he said.
After years of exploration, the research team finally discovered a new, cheap, non-toxic iron-based oxidant, replacing the chlorine-based and manganese-based oxidants that have been used for more than half a century, making the graphene preparation process fast, low-cost, and non-polluting. For industrial large-scale preparation. Reviewer of Nature-Communication commented: "This method is of great significance for the further application of graphene in the future."
With regard to the new graphene generation technology, Gao Chao explained that the iron oxidant molecules “run†very fast and can be quickly inserted into the graphite like a wedge to quickly stratify. “In the process, oxygen is also produced, which helps the 'top' layer of graphite, making the preparation faster,†he said.
The reason why this preparation method is "green" is that it has no explosion hazard, does not produce harmful substances, and is an environmentally friendly technology. At the same time, production experiment data shows that the method can prepare single-layer graphene within one hour, and is expected to realize large-scale industrial applications. In addition, after being prepared in an iron-based oxidizing agent solution, it can be dried and reduced to a graphene powder; when the material is produced, it can be "instantly dissolved" in a solvent. This feature allows graphene materials to be easily stored and transported.
The success of this study was not achieved overnight. It is understood that the research team has previously used graphene to produce various forms of macro materials and supercapacitors, lithium batteries and other devices.
The superb laboratory environment also shows their research history. There, the reporter saw large and small glass bottles containing various forms of graphene materials; there were laboratory-graphed graphene knotting pictures selected in the "Nature" magazine 2011 picture; even the laboratory slender bamboo leaves It also "floats" the graphene elastic aerogel that was selected as the world's lightest solid material record in 2013; as well as continuous graphene film that can be "spun" 10 meters per minute like film film... On this basis, they began to consider how to break through existing problems at the raw material level and promote the scale and low-cost preparation of single-layer graphene.
Possible future uses of graphene:
The material "graphene" in which the carbon atoms are hexagonally network-bonded has many excellent electrical, thermal and mechanical properties. Specifically, it has a carrier mobility of up to 200,000 cm 2 /Vs or more at room temperature, and far exceeds the resistance of copper to a large current density. For this reason, graphene has a transparent conductive film for a high-speed transistor, a touch panel, and a solar cell, and an electric wire having a lower cost than copper but capable of passing a large current compared with copper.
Recently, according to foreign media reports, graphene has a very strong light absorption capacity, and can also quickly convert the absorbed light into a laser with a shorter wavelength and higher frequency for a few femtoseconds. Scientists say that with this new discovery, they can invent laser-resistant emitters (graphene super-high temperature) that are more resistant to high temperatures in the future.
Of course, this discovery is currently only in the laboratory, and if scientists build a solid model, it will increase the lifetime and transmit power of the laser emitter.
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