Two recent discoveries, carbyne and stanene, show how these paths can combine to yield a material that’s more than double the strength of graphene and more than three times as tensile as diamond.
Often, breakthroughs in materials science follow one of three paths. They can occur through the discovery of a new compound, a design principle that guides the work, or through serendipitous discoveries.
What is Graphene?
Graphene is a new class of material that is only one atom thick. It is incredibly strong and conductive. Graphene is also very transparent, which allows for incredible light-emitting abilities. It can withstand many different liquids and gases, and is very resistant to corrosion.
The unique properties of graphene have made it an exciting new area of research, but there are still a number of barriers to widespread use. It currently costs between US$60,000 and $200,000 per ton.
However, this is a small price to pay for a material that could be extremely useful in a wide range of applications and industries. Companies are starting to take notice of graphene’s potential, with several large-scale projects underway. Some, like the electric car maker Daimler-Benz and tennis racket company Head, are already using graphene in their products.
Another promising development is a new technique called flash joule heating. This uses a powerful electrical current to reorganize carbon-carbon bonds into the graphene structure. It has the potential to turn any carbon-containing material into graphene for a very low cost.
As a result, there is a growing possibility that graphene will revolutionise the world of material science. It is likely to find many, many uses, from advanced electronic devices and insulators to fuel cells for electric cars.
Graphene Doping
Doping of graphene has received much attention in recent years due to the interest in using it in electronics. However, these methods have their drawbacks such as lack of environmental stability and industrial scalability.
A new approach to graphene doping has been reported in a paper from researchers at Rice University. It combines surface-adsorbate doping with an electrochemical redox reaction to increase the total Gibbs free energy of graphene and boost its performance as an electrode in batteries or catalytic devices like fuel cells.
In order to do this, the authors introduced a nitrogen molecule on top of a single-crystal graphene monolayer grown on silicon by CVD. The molecule is able to increase the Fermi level of it in a sizeable range near Van Hove filling, which makes it a better conductor for electronics and enhances its photovoltaic properties.
As a result, the electrical conductivity of the doped graphene increases and its resistance decreases with increasing doping concentration. In addition, the doped graphene is stable with time and temperature.
The electronic doping of graphene can occur through direct charge transfer between the adsorbate and the graphene surface, or through a change in the Fermi level of the adsorbate. The amount of electronic doping depends on the adsorbate LUMO and HOMO molecular orbitals.
Graphene Electrochemistry
Nitrogen doping is a powerful technique to tailor the properties of carbon materials and can be used to create new materials for various applications. This includes supercapacitors, solar fuels, batteries, molecular sensors, and metal-free electrocatalysts for oxygen reduction reactions (ORR)2,3,6,8,9,10,12,14,15,16,17,18,19.
This is especially important for the synthesis of high-quality, where the doping process may affect the crystalline quality and the chemical and electrical properties.
N-doped graphene is currently attracting interest because of its increased properties in physics, chemistry, biology and material science as compared to pristine. However, its formation mechanism still remains unclear.
As a result, graphitic-Ns quasi-adjacently occupy the same sublattice of it with a doping configuration of 12. This is due to the rotation of a C-C bond 90deg from a corresponding position in pristine.
Graphene Biosensing
As, Nitrogen doped graphene is an interesting new material to create new devices for sensing, we have studied the effect of N-doping on the electronic properties of graphene by analyzing dI/dV spectroscopy of pristine and doped graphene sub-lattices. The dI/dV spectra measured near a N2AA dopant (red curve) show a drastic change in the local density of states, with a pronounced dI/dV peak located at the Fermi level.
In addition, we have also compared Raman spectra of NG and pristine graphene sheets on SiO2 / Si substrates. The N-doped NG sheets also exhibit significant increases in Raman intensity for the same peaks as the undoped sheets, which indicate that the doping improves the vibrational properties of the substrate.
We have also examined the influence of N-doping on the surface chemistry of the NG sheet by performing XPS C1s line scans using a Microlab 310-F spectrometer. We found that the XPS C1s peaks of pristine and N-doped graphene sheets on SiO2 stoichiometrically correspond to different carbon atom arrangements within the honeycomb lattice.
Another potential benefit of nitrogen doping for graphene is that it is an efficient way to increase the electrical conductivity of a material. This is due to the fact that N has five valence electrons in its 2s and 2p atomic orbitals. This means that it is able to form bonds with the C atoms of graphene and thus enhance the electrical conductivity.
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