Graphene fever: "Hot" today, we must pay more attention to the future
June 6th is International Graphene Day. On this day, the research and application of graphene has once again become a hot topic of discussion in the scientific community. As a new type of nanomaterial with the thinnest, strongest and highest electrical and thermal conductivity known in the world, the development prospects of graphene are optimistic by many scientists, and graphene is therefore called "black gold". As the Nobel Prize winner Frank Wierzek said, graphene may be the only example from quantum theory to application.
How was graphene discovered? What is the application prospect? From research to application, what obstacles do we have to overcome?
1. The discovery of graphene: subverting the traditional thinking of physics
What is the "graphene" we often talk about?
"Graphene is only one word difference from graphene. In fact, graphene in the strict sense is a single-layer graphite sheet. Block the single-layer graphite sheet until it is thick enough to get graphite. And layer by layer of graphite. The single layer peeled off is graphene.” According to Peng Hailin, a professor at the School of Chemistry and Molecular Engineering of Peking University, graphene is a pure carbon material, 100% carbon material, a representative two-dimensional material. Its shape is expressed as a two-dimensional plane with a honeycomb and hexagonal structure composed of carbon atoms.
Graphene was once considered to be a hypothetical structure and could not exist independently.
According to Zhao Yang, a special researcher at the School of Chemistry and Chemical Engineering, Beijing Institute of Technology, the change occurred in 2004. The physicists Andre Gaim and Konstantin Novoselov of the University of Manchester in the United Kingdom successfully used the micromechanical stripping method for the first time. The separation of graphene from graphite overturned the traditional thinking in physics that “two-dimensional atomic crystals cannot exist stably at a finite temperature”. The two also won 2010 for “the pioneering experiment of two-dimensional graphene materials”. Nobel Prize in Physics.
"Although this discovery is of great significance, the preparation method used is very simple-use transparent tape to stick the highly oriented pyrolytic graphite, fold the sticky side, and then tear off the tape, the graphite flakes will be It is divided into two." Peng Hailin told reporters that by repeating this dissociation process, the graphite flakes will become thinner and thinner, and finally the two-dimensional crystalline material graphene with only one layer of carbon atoms will be obtained.
Of course, there are now more methods for preparing graphene-after several years of development, researchers have discovered more methods for preparing graphene, and this new material has entered the field of industrial production.
2. Exploring graphene: changing human life to a great extent
What can graphene be used for?
"Graphene is the thinnest, hardest, and best conductive nanomaterial currently known in the world. It is almost completely transparent and has great application prospects. It can be applied to various fields such as energy storage, medical treatment, and electronics." Zhao For example, Yang said, graphene is widely used in electrode materials of capacitors and batteries due to its high conductivity, good capacitance performance and heat dissipation performance.
Its high conductivity is also particularly suitable for high-frequency circuits, so graphene is expected to become a substitute for silicon, thereby increasing the operating speed of future computers and reducing energy consumption.
Cai Wei, a professor at the School of Physics of Nankai University, added that graphene can replace activated carbon, etc., to improve the capacity and efficiency of energy storage devices.
"Graphene composite materials are expected to replace traditional carbon fibers and be used to manufacture lighter aircraft and spacecraft. Specifically in the optical field, graphene's current application directions include flexible transparent electrodes, photovoltaic devices, light sources, light detectors, and ultra-fast Lasers, optical frequency converters and terahertz devices, etc."
"What's more worth mentioning is that graphene can be used to make flexible touch screens and touch screens. At present, ITO (Indium Tin Oxide) glass is generally used for touch screens in the market. ITO glass is relatively brittle and cannot be bent back and forth. Graphene The flexible nature of ene determines that it can break back and forth." Peng Hailin said.
Cai Wei said that the wide application of graphene will greatly change our current lives, providing a living environment with smoother information communication, more convenient life, and more environmentally friendly.
3. Research on graphene: not confined to low-end applications, but focus on future core technologies
"At present, our research on graphene is mainly focused on three aspects: one is the preparation and performance of graphene and its composite materials; the other is the study of basic physics based on graphene, such as quantum physics, polariton physics, etc. ; The third is graphene optoelectronic devices and their applications." Cai Wei introduced that at present, graphene research is gradually out of the laboratory. For example, in May 2020, Huawei released the first domestic 5G tablet, Huawei MatePadPro5G, which is equipped with ultra-thick 3D graphene. Heat dissipation technology, the total thickness reaches 400 microns.
But from research to application, graphene has to overcome many obstacles.
Zhao Yang said, “At this stage, there are still some difficulties in applying graphene directly to the actual situation. The main reason is that the production process of graphene is not yet mature, resulting in higher prices, poor quality, and low output. Although many The company's industrialization is in full swing, and some graphene products have also been introduced to the market, but graphene still cannot meet the needs of high-quality production and mass applications."
Starting from the actual situation in China, Peng Hailin listed a series of figures to reporters. According to statistics, since 2011, my country has ranked first in the world in the number of articles on graphene, close to 60,000, far exceeding the second place in the United States. my country’s graphene patents accounted for more than 54% of the world’s total, which is also far ahead.
At present, there are more than 5,000 companies involved in graphene business in my country, and they are showing a trend of rapid increase.
But there is also a crisis behind the numbers.
"China's graphene research and foreign countries are not completely on the same channel." Peng Hailin said frankly, "We pay more attention to products that can make money immediately. We have more than 700 graphene coating companies, as well as numerous graphene electric heaters and Big health companies, as well as more and more graphene underwear, graphene socks, graphene waist protectors, graphene masks, etc. Looking at foreign countries, they are more concerned about the future, the core technology of graphene and the development of tall products , Such as flexible graphene electronic devices, graphene optical communication devices, graphene terahertz detectors and other types of sensors, graphene separation membranes and seawater desalination technology. Obviously, these things cannot be realized immediately and cannot be expected within a few years. There are so big industries, but they may represent the future direction of graphene materials and devices."
This view is worth noting.
Liu Zhongfan, president of the Beijing Institute of Graphene Research and academician of the Chinese Academy of Sciences, has repeatedly pointed out that my country’s graphene research is still on the eve of industrialization, at least in its infancy. The core technology of the future.
Only with these core technologies can we have the future of the graphene industry.
4. Application of graphene: wider applications will bring mankind into the "carbon age"
Where is the way forward for the development of graphene?
"In the future, graphene should develop in the direction of industrialization. Its use can be reflected in battery electrode materials for wearable smart phones, watches, electric vehicles, military body armor, mechanical protection materials for aviation devices, and some flexible electronics. Display screens and electronic components." Zhao Yang thinks.
Cai Wei said that from the perspective of longer-term development, graphene should promote the development of basic physics. At present, graphene has promoted the development of the entire two-dimensional material field in order to explore the basic physics and applications of van der Waals two-dimensional heterogeneous materials. It provides the possibility, such as the corner double-layer graphene can achieve superconductivity, and the elementary excitation energy in graphene can achieve extremely strong light-matter interaction.
"Of course, graphene needs to be applied in new scenarios. For example, graphene-based ultra-sensitive photodetectors can be applied in aerospace, unmanned driving, biological detection and other fields, as well as graphene and other two-dimensional materials or existing Silicon-based nanosystem integration appears in 6G communication devices and the like."
"Academician Liu Zhongfan once outlined three prospects for graphene materials. The first prospect is similar to carbon fiber materials, and it has found indispensable uses in certain fields and has become a "hands-on" application. The second prospect is similar to plastics. People invented plastic a hundred years ago, which greatly facilitated human life and has penetrated into all aspects of daily life. Graphene materials also have this potential, and may enter our daily lives like plastic in the future. The third kind of future is similar to Silicon materials. Without silicon materials, there would be no integrated circuits, and naturally, we would not be able to enter the information age. It can even be said that we are now living in the "silicon age". Perfect graphene materials have far superior optics and electricity than silicon materials. It can be used to make future information devices.” Peng Hailin said, the first thing to be solved is the preparation of graphene materials. In the future, high-quality graphene materials can be combined or integrated with traditional silicon technology to find a “killer”. "Class use, it is possible to replace silicon-based materials to manufacture "carbon-based electronic devices and integrated circuits", thereby bringing mankind into the "carbon age."
(Our reporter Jin Haotian, our correspondent Han Fang)