Talking graphene standardization with NPL's Andrew J. Pollard

Dr. Andrew J. Pollard (NPL)In November 2017, after years of work, the International Organization for Standardization (ISO) released its first graphene standard, the ISO/TS 80004-13:2017. The effort was led by the UK's National Physical Laboratory (NPL).

We recently discussed this interesting and important development with the NPL's Dr. Andrew J. Pollard. Dr. Andrew leads the NPL Surface and Nanoanalysis Group's research into the structural and chemical characterization of graphene and related 2D materials, and he is also a member of the ISO working group 'Measurement and Characterization' within the 'Nanotechnologies' Technical Committee (TC229), and a UK nominated expert for the international graphene standards.

Hello Andy, and thank you for this interview. We know that NPL pioneered the effort in the new ISO standard, can you tell us why do you believe such standards are of vital importance?

As a new material that has spawned an emerging industry, graphene has the potential to improve many of the products we all use every day. However, for industry around the world to be able to develop innovative products with this two-dimensional material, they need to know what the properties actually are of the materials they are using.

This is especially important for instilling trust in the supply chain, as you have companies producing ‘graphene’ and selling them to other companies developing products or intermediates. This product may then be used by yet another company in a well-regulated industry, such as the aerospace sector. This is where international standards come in. By producing international standards within ISO that have been agreed by the international community, companies around the world can use the language and processes within these standards, so that the whole supply chain knows exactly what they are purchasing or providing to other companies. This accelerates commercialization, increases efficiency, decreases costs and ultimately reduces issues between companies.

Q: The new standard lists terms and definitions for graphene and related 2D materials. Can you detail in short the most important naming for production methods and properties of graphene?

This first ISO standard for graphene addresses the issues in the terminology used both for graphene itself and related two-dimensional (2D) materials, by defining commonly used terms within industry and academia.

Firstly, the term ‘graphene’ itself, which is commonly used to describe black powders with graphite flakes of nanoscale dimensions. In this international standard, graphene is defined as a single layer of graphene, as has actually been the case within ISO since 2010, but also defines terms such as few-layer graphene, which is 3-10 layers of graphene. Furthermore, it defines the abbreviations for graphene (1LG), bilayer graphene (2LG), few-layer graphene (FLG), graphene oxide (GO) and graphene nanoplatelet (GNP). The latter term is also defined as 1 to 3 nm (corresponding to few-layer graphene), to distinguish it from graphite nanoplatelets (less than 100 nm in thickness).

The term 2D material is also defined. Furthermore, many different production methods are included, such as CVD-grown graphene and epitaxial graphene, as are material properties, such as flake size, and techniques used to measure these materials.

Q: Most people will be interested in the definition of when a graphene-based material should be called graphene, few-layer graphene, or graphite. The new standard details these distinctions. Do you believe the industry at large will adopt this new naming conventions?

We have already seen both academics and industry start to adopt these naming conventions in countries such as the UK, US and China and I believe the use of this standard will continue to grow as more companies become aware of this standard. Importantly, end-users will want to see material data sheets referencing this terminology standard, so they can trust the claims of producers, meaning that more and more producers will need to state that they are using the terms within ISO/TS 80004-13:2017.

Q: Different production method naming is also of interest, especially as each company claims to have a proprietary and unique production method. How does the new standard handle these methods?

There are 19 production methods for graphene and related 2D materials detailed in the standard itself, with a further 6 defined for production of graphene nanoribbons. The typical terms used in industry have been included, however, not every single term coined for each of the processes used by the hundreds of companies now producing graphene are necessarily included. Part of determining more niche production methods terms used would be down to which companies chose to input into the ISO standard itself, during the development process. This is done through involvement in the national standards bodies of each country.

Q: Do you see this standard or at least parts of it being adopted by more standard bodies all over the world?

This standard is already in use by both the ISO and IEC, which means that the 161 national standards bodies will automatically use this international standard, so I think other international standard bodies will also follow the lead of this document, as they are not developing a standard on graphene terminology themselves.

Q: What are the next steps for ISO's graphene standards initiative?

Terminology and nomenclature is an extremely important first step for any industry. However, it is extremely important that end-users of graphene who know what properties they require (whether it is a property such as flake size, number of layers or the chemical functional groups present), can look at the data sheet of a material from a graphene producer and directly compare it with another product from another producer.

To do this we need internationally standardized measurement methods for the material properties that will ultimately affect any real-world product. These measurement standards are currently being developed in ISO. Of course, these standardized measurements need to be based on accurate, precise and comparable methods, which requires detailed measurement science investigations. To this end, international interlaboratory comparisons have now started for several techniques within the Versailles Project on Advanced Materials and Standards (VAMAS), the results of which will feed directly into ISO standards under-development, with hopefully more studies to follow.

Q: Finally, we'll be happy to hear your personal thoughts of this standards process - it's been years in the making, we are sure it feels great to finally see it published!

As the international community needs to reach consensus and does not necessarily have the same starting positions, it does take time to develop these kind of standards before they are published. At the same time, this amount of time taken is because of the voluntary nature of leading a standard and the experts who contribute to its development, coupled with the level of rigour required to produce international standards that are fit-for-purpose.

All of that said, it was extremely satisfying to see the standard published and different people around the world now referring to it!

Thanks Dr. Andrew, we wish you good luck in the future, and we hope to hear of advances in graphene standardization efforts soon!

Posted: May 22,2018 by Ron Mertens