Not much gossip, let’s take a look at the structural differences between the two first:
Graphene with perfect lattice structure
Graphene, did you choose the right one?
Graphene defects are formed due to various causes, and the positions of formation are mostly random and uncontrollable. This makes it difficult to quantify the relationship between graphene defects and properties, but no matter which type of defect it is, it will seriously affect the following aspects of Graphene properties:
Defects cause graphene conductivity to decrease
The appearance of graphene defects changes the bond length of the valence bonds between atoms, and at the same time changes the types of hybrid orbitals of some carbon atoms. The changes in bond lengths and orbitals make the electrical properties of the graphene defect regions change. Graphene point defects and single-hole defects form electron wave scattering centers on the surface of graphene. Such centers affect the transfer of electrons and ultimately reduce the conductivity of graphene.
The mechanical properties of graphene are severely affected
The influence of introducing defects outside of graphene on its mechanical properties is also developing. Studies have found that Young's modulus of graphene with C-O-C heteroatom defects is 42.4% lower than that of defect-free graphene.
Intrinsic defects of graphene, especially hole defects, have a greater impact on the tensile strength of graphene than external defects, and external defects more only affect the deformation modulus of graphene.
The thermal conductivity of graphene is greatly reduced
Graphene itself has great thermal conductivity, about 5000 W/m·K. The existence of defects will change the thermal conductivity. For example, if there are point defects or single-hole defects in graphene, the thermal conductivity of graphene will rapidly decrease to 20% of the defect-free condition as the defect concentration increases. The study found that when some carbon atoms on graphene become sp-hybridized, assuming that such a carbon atom still remains connected to the other three carbon atoms, and another valence bond is connected to a hydrogen atom, the out-of-plane caused by this hydrogen atom The introduction of defects by heteroatoms will reduce the thermal conductivity of graphene. Even if such defects are introduced to 2.5% of the carbon atoms in graphene, the thermal conductivity of graphene will be reduced by 40%. Further research has also shown that randomly distributed hydrogen atom defects are more effective than those concentrated in a certain area. The thermal conductivity of graphene is very harmful.
Significantly reduced chemical stability
Defects in the graphene lattice will generate a large number of reaction sites, resulting in a significant decrease in the stability of graphene. In addition, when hydrophilic groups such as hydroxyl and carboxyl groups are introduced, the hydrophilicity of graphene will also change, which will further damage the stability of graphene.
Therefore, as a scientific researcher, you must be careful in the selection of experimental materials. Only high-quality graphene can make your experiments meet expectations. Conversely, materials with more serious defects not only fail to bring the expected results to the experiment, but the final performance may not be as good as the original.