Recently, Chinese scientists succeeded in increasing the production speed of single-crystal graphene films by 150 times by continuously supplying oxygen.

On August 8, Nature Nanotechnology, one of the top international academic journals, published an online Chinese scientist's paper "Continuous Ultraviolet Growth of single-crystal Graphene with Continuous Oxygen Supply" crystal graphene assisted by a continuous oxygen supply).

Research teams from Peking University, Wuhan University, Nanfang University of Science and Technology and Hong Kong Polytechnic University in China said they placed an oxide at 15 microns below the copper foil of the catalyst when preparing a single-crystal graphene film using chemical vapor deposition (CVD) Substrate materials, which provide continuous oxygen supply for the synthesis of graphene films, greatly reduce the energy barrier of decomposition of carbon materials (the minimum energy that activators can participate in the chemical reaction), and average the chemical vapor deposition A production speed of less than 0.4 μm / sec was increased 150-fold to 60 μm / sec and a single-crystal graphene film with a lateral size of 0.3 mm was successfully fabricated in 5 seconds. The researchers said that this is more efficient than previous fabrication The method is two orders of magnitude higher.

According to the "Terms, Definitions and Codes of Graphene Materials" promulgated by the State Standardization Administration in April this year, graphene is defined as carbon consisting of one carbon atom combined with three neighboring neighboring carbon atoms to form a honeycomb structure Monolayer; Graphene film refers to the growth of a certain substrate on the single-layer graphene, double-graphene or multilayer graphene, and can be transferred from the growth of the substrate to other substrates.

Graphene powders and graphene films are currently two major forms of graphene materials. The former is more doped in other materials used, and more applications in the field of coatings and lithium-ion batteries; graphene films in the fields of electronics, photonics and optoelectronic devices is widely used, with great prospects for development.

At present, several common preparation methods of graphene materials are mechanical stripping method, chemical vapor deposition method, redox method, liquid phase stripping method, pyrolysis method and intercalation stripping method. Among them, the liquid phase stripping method and the redox method are mainly used for preparing graphene powder, and the chemical vapor deposition method has become the most common method for preparing large-size graphene films due to its simplicity of operation and cost-effectiveness. Chemical vapor deposition refers to a method of decomposing and depositing a carbon atom-containing gas on a surface of a substrate (such as a metal or a nonmetal) at a high temperature to form a graphene material.

The United States "IEEE" magazine reported August 9 reported that the Chinese scientific research team in the experimental chemical vapor deposition method, the oxide substrate material placed in 800 degrees Celsius above the high temperature environment, so that it can continue to release oxygen. Electron spectroscopy measurements showed that the oxide backing material did release oxygen. Although the amount of oxygen produced is rather limited, the small space between the oxide substrate material and the copper foil creates a trap effect (the effect of a certain type of non-equilibrium charge carriers accumulating in the non-equilibrium charge carriers) ), Thus expanding the effectiveness of oxygen play.

The researchers believe that if this speeding synthetic chemical vapor deposition and rolling manufacturing technology combined, it will be possible to achieve high-quality single-crystal graphene film production.

Graphene was discovered in 2004 by British scientists André Gem and Konstantin Novoselov, and graphene has potential in many fields due to its excellent physical properties of electrical conductivity, thermal conductivity, light transmission and strength The value of its application has quickly become one of the new materials for the development of major powers in the world.

The Outline of the Thirteenth Five-Year Plan adopted by the "NPC and CPPCC" this year clearly states that nano-functional materials such as graphene should be vigorously developed. At the end of July, the "13th Five-Year Plan for National Science and Technology Innovation" clearly states that it is necessary to give play to the role of graphite Ene and other leading role in the development of new materials industry.

In September last year, the National Strategic Advisory Committee on Constructing Powerful Countries announced the "2015-2010 Technology Roadmap for Key Areas of Made in China" (2015 version), putting forward that the overall goal of China's graphene industry is "to form 10 billion industrial scale in 2020 and 2025 in overall industry Size exceeded one hundred billion. " According to China's graphene industry technology innovation strategic alliance released in June this year, "2016 Global Graphene Industry Research Report" shows that the current annual global graphene production capacity reached 100 tons, the next 5-10 years will reach thousands of tons. And it is estimated that by 2020, the global graphene industry will form a complete industrial chain, and the market scale will reach 100 billion yuan, of which China will account for 50% -80%.

At present, there are three main graphene film production lines in China. The graphene film production line in Changzhou, Jiangsu Province, with an annual output of 30,000 square meters put into operation in May 2013, is also the first graphene film production line in China. The graphene film production line opened in Chongqing in October 2013 has been put into operation recently and the annual output Reached 1 million square meters, becoming the world's largest graphene film production line; July 2016, the first continuous production line of graphene film is also built in Changzhou, Jiangsu.

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