Dr. Andrew Pollard

NPL, UK
Andrew Pollard leads NPL’s research into the structural and chemical characterisation of graphene and related 2D materials, with a focus on enabling industrial commercialisation in this area. This metrology research has allowed the development of several international standards addressing the measurement of 2D materials, either published or in progress within the ISO 'Nanotechnologies' Technical Committee (TC229).

Andrew is a Visiting Lecturer at the University of Manchester, the co-chair of the VAMAS Technical Working Area 'TWA 41: Graphene and Related 2D Materials', Metrologist-in-Residence at the Henry Royce Institute, the Secretary of the 'Materials and Characterisation' Group at the Institute of Physics (IOP) and the recipient of the Royal Society of Chemistry's '2018 Rising Star in Industry Award'.

Talk title: The importance, challenges and solutions for measuring 2D materials
Many different graphene related two-dimensional materials (GR2Ms) from different commercial suppliers are now in real-world products used around the world. However, without an understanding of the properties of the materials available in the supply chain, both these and new applications cannot be efficiently developed and improved. Thus, there is a need for reliable, accurate and precise measurements for material testing, which are standardised across the industry and therefore allow end-users to be able to compare commercially-available materials from around the world.

Over several years a set of international measurement standards have been developed to include the techniques and procedures for measuring the material properties of 2D materials, such as chemical vapour deposition (CVD) produced graphene, graphene nanoplatelets (and different chemically-functionalised versions thereof), reduced graphene oxide and graphene oxide[1].

To ensure the accuracy of these measurement protocols so they can be undertaken with known uncertainties, fundamental metrology studies and international interlaboratory comparisons must be undertaken. These allow an improved understanding of the sources of uncertainty, how to reduce these uncertainties and ultimately the size of the uncertainties that can be expected in these measurements, when comparing products measured the same way, but in different laboratories around the world.

These studies have highlighted many improvements in the techniques included in international measurement standards, such as atomic force microscopy (AFM)[2], Raman spectroscopy [3], X-ray photoelectron spectroscopy (XPS)[4], gas physisorption (using the Brunauer-Emmett-Teller (BET) method)[5], thermogravimetric analysis (TGA)[6] and electron microscopy. Both the challenges encountered, solutions developed and benefits of these techniques will be discussed herein.

[1]          Clifford et al, Nat. Rev. Phys., 3 (2021) 233-235
[2]          Bu et al, Nanotech., 32 (2023) 22
[3]          Turner et al. 2D Mater., 9 (2022) 035010
[4]          Reed et al, Carbon, 211 (2023) 118054
[5]          Marchesini et al, Carbon, 167 (2020) 585-595
[6]          Yap et al, Anal. Chem., 95 (2023) 5176-5186