According to reports, researchers at the University of Colorado in the United States have successfully synthesized graphdiyne, which may open up a new way for the study of electronic, optical and semiconductor materials. In fact, the research on the synthesis of graphyne has always been the goal of scientists. As early as 2010, the team of academician Li Yuliang in my country synthesized graphyne for the first time in the world.
Many of us have heard of graphene and know that the 2010 Nobel Prize in Physics was awarded to the developer of graphene materials. Graphyne and graphene are just one word apart. Is there any connection between them? Is graphdiyne comparable to graphene? Here we invite Sun Yixuan, a Ph.D. from the Institute of Chemistry, Chinese Academy of Sciences, to give some popular science introductions.
Scientists have confirmed that graphene is the strongest known material in the world, harder than diamond and more than 100 times stronger than the world's hardest steel. When the Royal Swedish Academy of Sciences awarded the Nobel Prize in Physics in 2010, it was like this: "A hammock made of single-layer graphene can carry a 4-kilogram rabbit." The light transmittance is as high as 97.7%, so if there is such a hammock, it is not only invisible to the naked eye, but even to many instruments. What we see will be a rabbit hovering in the air. There are also estimates that if graphene sheets are stacked so that they are the same thickness as food wrap, they can carry a 2-ton car.
In terms of thermoelectric properties, in the "two-dimensional world" of graphene, the motion of electrons has a very peculiar property, that is, the mass of electrons seems to be non-existent, and its conduction speed can reach 1/300 of the speed of light, far exceeding The speed of movement of electrons in a general conductor. Coupled with the high degree of perfection of the graphene structure at room temperature, the transmission of electrons and the response to external fields are super fast, which makes graphene have extraordinary electrical and thermal conductivity.
And more importantly, graphene can also be used to make transistors. Due to the high stability of the graphene structure, such transistors can still work stably on a scale close to a single atom. If graphene were used to replace silicon in a supercomputer, the computer would run hundreds of times faster than it does today. Therefore, many people believe that graphene will become the successor of silicon, ushering in a new era of miniaturization in the field of technology.
In addition to its ultra-high strength and toughness, graphene is almost completely transparent, and even the smallest single-molecule atoms (helium atoms) cannot pass through, only absorbing about 2.3% of light, and it is also impermeable to water, air and air. The ability to resist strong acids and alkalis makes it an ideal material for making protective films. Graphene is both conductive and highly transparent, making it very suitable as a raw material for transparent electronic products, such as touch screens, solar panels, etc.
The researchers developed a new type of energy storage device, the tiny graphene supercapacitor, by taking advantage of the rapid and massive shuttle motion of lithium ions between the graphene surface and electrodes. The device charges or discharges 100 to 1,000 times faster than conventional batteries, and can fully charge a phone or even a car in under a minute.
Because of this, some people say that if the 20th century was the century of silicon, then the 21st century was the century of graphene.
Graphene is already so amazing, so what about graphdiyne? Is there anything magical about it?
Like graphene, graphdiyne is only composed of carbon atoms, and it is also a two-dimensional crystal with only one atomic thickness. The difference is that the plane atomic structure of graphene is hexagonal, also known as the honeycomb lattice structure; while the plane atomic structure of graphyne can have several different two-dimensional structures, which can theoretically be in countless forms. exist, and at least 6 graphdiyne isomers have been reported so far.
It is precisely because of its isomeric structure that graphdiyne has some unique electronic conduction, mechanical and optical properties. In addition, graphdiyne also inherently has charge carriers, unlike graphene, which requires additional doping, so it can be used as a semiconductor material for electronic components.
As early as 1968, theoretical chemist Bowman confirmed the existence of the graphdiyne structure through theoretical calculations. However, in order to synthesize graphdiyne in practice, there are still many huge difficulties. We can understand that the planar carbon atomic structure of graphene and the single-layer planar carbon atomic structure of graphite are the same after all, so graphene can also be synthesized with graphite as the handle, while the difficulty of synthesizing graphyne is obviously greater. .
The growing production of graphene has made graphene and related 2D materials more accessible and cheaper for industry and research.
The spray deposition machine - developed for the Graphene Flagship - can coat any material with graphene for use in the supercapacitor and battery industries.
Scientists have been working tirelessly on this. In 2010, the team of Academician Li Yuliang of the Institute of Chemistry of the Chinese Academy of Sciences made an important breakthrough in the research of graphyne, and synthesized graphyne for the first time in the world, opening up a new field of carbon materials. Li Yuliang and his team have been exploring synthetic chemistry of planar carbon since the mid-1990s. In the synthesis of graphyne, they start from the molecular design of the source, and gradually try to synthesize some molecular fragments. Until one day in the process of reading the literature, researcher Li Yuliang suddenly thought of a chemical method that may form a large-scale graphene film. They chemically synthesized graphdiyne in situ on the surface of copper sheets and successfully obtained a new allotrope of large-area (3.61 cm2) carbon—graphyne thin film for the first time. In this process, the copper foil not only acts as a catalyst for the cross-coupling reaction, a growth substrate, but also provides a large planar substrate for the directional polymerization required for the growth of graphdiyne thin films.
The research paper published in "Nature Synthesis" on May 9 this year provides a new way for the synthesis and preparation of graphdiyne. Corresponding author Wei Zhang, a professor of chemistry at the University of Colorado at Boulder, and his team, by using an organic reaction process known as an alkyne transposition reaction, refragmentation or cleavage and recombination under thermodynamic and kinetic control Alkyl chemical bonds, also successfully produced graphdiyne.
Graphyne is known as the most stable synthetic diacetylenic carbon allotrope. Due to its special electronic structure and excellent semiconductor properties similar to silicon, graphdiyne is expected to be widely used in electronics and semiconductor fields.
The diffusion mode of lithium in graphite is in-plane diffusion, that is, interlayer diffusion. Different from graphite, graphdiyne has both a two-dimensional planar structure and a three-dimensional pore structure, in which lithium has two diffusion modes, in-plane and out-of-plane, which makes graphdiyne have good application potential in lithium-ion batteries. Graphdiyne is an ideal lithium storage material and can be used as a negative electrode material for high energy density storage in lithium-ion batteries. Scientists also predict that it will have an extraordinary impact in the field of new energy.
Graphyne may also have some unexpected magical properties. According to a report published in Science and Technology Daily in 2020, the low-dimensional optoelectronic materials and devices team of Shandong University of Technology found that graphdiyne has excellent ultraviolet nonlinear properties and can absorb ultraviolet light "just right". The related results were published in the internationally renowned journal Nanoscale. The so-called ultraviolet nonlinear material is able to allow the passage of ultraviolet rays when the intensity of ultraviolet rays is relatively low, but if the intensity of ultraviolet rays is higher than a certain threshold, the material will magically block the excess ultraviolet rays and form the protection of biological cells. , making it an ideal UV protection material.
The British magazine "Nanotechnology" once commented: "Graphyne is one of the materials with the most potential and commercial value in the future, and it will be widely used in many fields."
In the field of synthesizing graphyne, Chinese scientists have made pioneering achievements . In order to obtain a method for large-scale industrial preparation of graphdiyne, more arduous efforts from scientists around the world are needed, and the prospect is promising.
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