- 2D Crystals
NUS CA2DM, one of the world leaders in 2D materials research is pushing the boundary in magnetic field detection and looking for industry partners to develop world's most sensitive magnetic sensor and the first one based on 2D hetero-structures. This sensor has broad applications for automation, inspection, biomedical-imaging and other industrial applications.
The active core sensing area of this sensor is made of graphene and boron nitride hetero-structure. It reacts strongly to magnetic field with magneto-resistance change as high as 10^5 % higher than any AMR, GMR and TMR sensors. In addition, it can be used in wide range of magnetic field with extremely low power consumption of 10 nW.
Since the early stage of the graphene production, quality was pointed out as one of the main issues to be solved in the future. Even from the academic point of view the quality of graphene and other 2D materials has not yet reached an unanimity. On the other extreme, many companies popped-up all around the world in recent years, offering all sort of graphene “products”. So how to insure that what you are buying to do your R&D is really graphene?
Taking in consideration our definition of graphene (10 layers or less) we have tested different graphene products (powder and solutions) from more than 30 companies, using academically accepted protocols. In this study we evaluated their quality in terms of number of layers, flake (crystallite) size, spectral quality (Raman), chemical purity, and other characteristics.
Here are some of our findings.
The grey areas represent the average and two standard deviations (m ± 2σ, or 95% of the population in a Gaussian distribution) of the numbers of layers (X axis) and crystallite size (Y axis) found for every tested Graphene product (products with more than 300 layers are not shown).
Also, many institutions, such as The Graphene Council, Graphene Flagship, Graphene-Info, and International Organization for Standardization (ISO), have highlighted the need of Graphene Standards to enable more effective developments in this area.
And yes, you are probably buying Graphite!
At the Centre for Advanced 2D Materials (previously, Graphene Research Centre) we have been working on basic science and the technology of graphene and other 2D Materials. One of our goals is to deliver an industrial definition of graphene that can be used worldwide and will help to guide graphene produces, developers, and researchers.
If you have not heard about graphene it is either because you are not connected to the internet or you live in another planet. Graphene was isolated in 2004 by Geim and Novoselov using a scotch-tape method to exfoliate graphite. In 2010, the Nobel Prize in Physics was awarded to duo in recognition for the amazing feat.Graphene has been called as the new Wonder Material by many, and more than 5 billion US dollars have been invested worldwide in research related to this material in the last few years.
The strict scientific definition of GRAPHENE is that of a pure-carbon mono-layer material, one atom thick (0.34 nm in thickness), with a planar sp²-bonded carbon structure that are densely packed in a honeycomb-shaped crystal, as shown in the figure above on the left. Graphite, on the other hand, is an enormously large number stacked graphene layers forming a three dimensional (3D) structure, as shown in the figure above on the right.
Over the last 12 years, a wide range of definitions have emerged for graphene-based materials due to the large number of production processes that have been developed. The definitions used by the graphene suppliers for different graphene-based materials may vary from a single-layer of carbon atoms to even hundreds of layers in a stack, which is essentially thin graphite.
Much of the noise about Graphene has arouse from the fact that this material has amazing properties including ultimate tensile strength of 130 GPa (hundreds of times stronger than steel), very high electron mobility even at room temperature, thermal conductivity higher than 2,000 W m−1 K−1, and optical transparency around 98% (yes it is transparent). Usually, the higher the number of graphene layers the less outstanding the properties are. However, multi-layered graphene (below 10 layers) still have very interesting properties from the application point of view.
The major current applications of graphene range from composites, coatings, separation membranes, and batteries to high-end products such as touchscreen displays and transistors. But who knows what the future can bring?
Furthermore, graphene is a nanomaterial by ISO definition because it has at least one dimension smaller than 100 nm. New ISO standards have currently been drafted for further clarity on this definition, but also to help the market to have a better understanding on what is real graphene or simply thin graphite (95% of the global suppliers sell thin graphite only!).
Until now, the graphene supply market is still very blur and misleading, which is preventing the application companies to bet on the graphene R&D for future products.
At the Centre for Advanced 2D Materials (previously, Graphene Research Centre) we have been working on basic science and the technology of graphene and other 2D Materials. One of our goals is to deliver an industrial definition of graphene that can be used worldwide and will help to guide graphene produces, developers, and researchers. Furthermore, at CA2DM we are also producing extreme high quality graphene that can be used in graphene applications, not graphite ones. Graphite is not graphene, and these two materials have very different properties and applications.
In the next posts we will show what is the situation of graphene production worldwide and the work done at CA2DM in order to make graphene into a world revolutionizing material.
K 2016, the biggest plastics and rubber trade fair worldwide, held from 19th to 26th October 2016 was a grand success with 230,000 trade visitors from over 160 countries. The plastics and rubber industries presented their entire performance spectrum and a whole diversity of innovative applications. There were 3,285 exhibitors from all continents who introduced their latest development.
Surprisingly, there was not a single product exhibited using graphene, the wonder material. There were only three companies that were selling graphene as a raw material. Most of the companies never even heard about graphene. The important question is why? There are many answers to this question and few of them were put forward by the companies themselves: 1) Bottlenecks in large scale production of graphene 2) Lack of standards in graphene production 3) Low hanging application such as composites and coatings are still at R&D stage 4) Lack of knowledge dissemination about the material etc.
Centre for Advance 2D Materials and Graphene Research Centre at National University of Singapore are working towards solving all the above issues. More on this in the upcoming blog posts.
We hope to joins hands and make graphene a success by K 2019!
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