523 / 2019-03-19 20:53:55

The Structural Transformation and Properties of Graphdiyne and Its Derivatives under High Pressure

high pressure; graphdiyne; bonding transition

全体主题 > High Pressure Physics and Materials Science

The carbon atoms have various hybrid forms such as sp, sp2 and sp3, and the structure is very rich.The carbon element can form a variety of allotropes, including the well-recognized new carbon materials with excellent properties, such as diamond, graphite, fullerenes, carbon nanotubes and graphene.In recent years, as another new carbon allotrope, the emergence of graphdiyne has once again attracted scientists' attention.Since the concept of graphdiyne was proposed in 1968, until 2010, the Yuliang Li ’s group successfully synthesized a large-area polymer graphdiyne film with a two-dimensional structure.Different from the traditional allotrope, graphdiyne is a conjugated structure composed of sp-carbon and sp2-carbon, and the benzene ring is connected by a acetylene bond to form a two-dimensional planar network.
High pressure is an important means to regulate the hybrid form of carbon atoms.Graphdiyne provides a good reaction site for the construction of three-dimensional carbon materials due to its active carbyne group.Therefore, with graphdiyne as a precursor and high pressure extreme conditions, it is possible to synthesize a more abundant carbon structure.
We used Raman, Infrared spectroscopy, impedance analyzer, X-ray diffraction (XRD) and other in situ characterization methods to characterize the carbon bonding, electrochemical properties and crystal structure of graphene and its derivatives.The spectrum results indicate that the graphdiyne begins to undergo a sp→sp2 bond transition at 4 GPa and completes at 13 GPa.At the same time, the in situ impedance spectrum of graphdiyne at high pressure shows that the low-frequency impedance value decreases significantly from 4GPa.Then,there is an upward trend at 11GPa, and the transition pressure point corresponds to the spectrum.This result may prove that starting from 4GPa, thegraphdiyne molecules begin to undergo the sp→sp2 bond transition.It can be electrically conductive from the layer to between layers.The resistance decreases and the conductivity increases significantly.The results of Raman and Infrared spectroscopy show that 1,3,5-triynylbenzene has a significant color change under the microscope from 4GPa.At the same time, the analysis of the spectral results showed that the acetylene bond began to disappear at 4 GPa, and the bonds between the carbon atoms began to polymerize.This project enriches the study of the bond transition of sp-carbon structures under high pressure.It is a good supplement for the experimental study of graphene and its derivatives under high pressure.It lays the foundation for the potential application of graphene as a design and preparation of three-dimensional carbon materials.