Graphene is a two-dimensional carbon nanomaterial with hexagonal honeycomb lattice composed of carbon atoms with sp² hybrid orbitals.
Graphene has excellent optical, electrical, and mechanical properties, and has important application prospects in materials science, micro / nano processing, energy, biomedicine, and drug delivery. It is considered to be a revolutionary material in the future.
Andrei Gem and Konstantin Novoselov, physicists at the University of Manchester, UK, successfully isolated graphene from graphite by micromechanical exfoliation, so they won the 2010 Nobel Prize in Physics . The common powder production methods of graphene are mechanical peeling method, redox method, SiC epitaxial growth method, and the thin film production method –chemical vapor deposition (CVD).
Recently, Professor Liu Chunsheng's group at Nanjing University of Posts and Telecommunications has theoretically studied the effects of superconjugation on the energy bands, mechanical and electrical properties of two-dimensional materials. Drawing on the "bottom-up" method of assembling graphene, the authors assembled methyl ether molecules with a super-conjugation effect into a new two-dimensional oxycarbon compound, and named it "graphether".
The research result was published in the journal Nanoscale, titled "Graphether: a two-dimensional oxocarbon as a direct wide-band-gap semiconductor with high mechanical and electrical performances" DOI: 10.1039 / C9NR08071F.
Simply put, it comes from the hydrogenation of graphene, and a hydrogen atom is introduced next to each carbon atom. Graphane is similar to graphene, a two-dimensional alkane. Its name is also based on the nomenclature of organic chemistry, which means saturated carbon Hydrogen compounds. Researchers said that although pure graphene is extremely stable in chemical properties, they found that hydrogen atoms can react with it, turning highly conductive graphene materials into new graphane materials with insulating properties. This experiment proved that the properties of graphene can be changed by chemical methods, which paved the way for the preparation of other graphene-based chemical derivatives. Similar to graphane, fluorine and nitrogen hybrids can also be introduced to produce other graphene derivatives.
In addition, corresponding to the complete hydrogenation of graphane, when the hydrogenation on graphene is incomplete, it is called hydrogenated graphene (including reduction of graphene oxide for hydrogenation). Hydrogenated graphene can exhibit a certain ferromagnetism and a band structure that can be adjusted according to the degree of hydrogenation. In addition, the material is also considered as a promising hydrogen storage material because reversible hydrogenation and dehydrogenation can occur.
In 2010, researchers from the academician Li Yuliang of the Chinese Academy of Sciences Key Laboratory of Mechano-Solids have synthesized graphyne for the first time, opening up a new field of carbon materials. Graphyne is a full-carbon molecule with benzene rings conjugated by a 1,3-diyne bond to form a two-dimensional planar network structure. It has rich carbon chemical bonds, a large conjugate system, wide interplanar spacing, excellent chemical stability, and Semiconductor performance is expected to be widely used in electronics, semiconductors and new energy fields.
Graphite ether has excellent dynamic and thermodynamic stability, is a direct band gap wide band gap semiconductor (energy gap 2.39 eV), and has good response in the ultraviolet region. In addition, it can maintain direct band gap characteristics under uniaxial or biaxial strain of -10% -10%. Due to the super-conjugation effect, the in-plane stiffness (459.8 N m-1) in the direction of the graphene armchair exceeds that of graphene (342 N m-1). Compared with the lower carrier mobility of hydrogenated and fluorinated graphene (101-2550px2V-1s-1), the electron mobility of graphene ether reached 2575px2V-1s-1 in both chair and zigzag directions. The above-mentioned superior properties make graphite ether materials expected to be used in nanoelectronic and photovoltaic devices.
Graphite ether is not only a direct band gap wide band gap semiconductor, but also has high in-plane stiffness and electron mobility. In addition, Pt (100) proved to be a potential substrate for the synthesis of graphene from the bottom up. These results are expected to provide new ideas for the design and preparation of graphene-like materials with superconjugation effects, and promote their innovative applications in next-generation electronic and optoelectronic devices.