ISO TS 21356-1:2021

TECHNICAL ISO/TS
SPECIFICATION 21356-1
First edition
2021-03
Nanotechnologies — Structural
characterization of graphene —
Part 1:
Graphene from powders and
dispersions
Nanotechnologies — Caractérisation structurelle du graphène —
Partie 1: Graphène issu de poudres et de dispersions
Reference number
ISO/TS 21356-1:2021(E)
©
ISO 2021
ISO/TS 21356-1:2021(E)
© ISO 2021
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ii © ISO 2021 – All rights reserved

ISO/TS 21356-1:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Sequence of measurement methods . 3
6 Rapid test for graphitic material using Raman spectroscopy . 5
7 Preparing a liquid dispersion . 7
7.1 General . 7
7.2 Preparing a dispersion of the correct concentration . 7
7.2.1 Powder samples . 7
7.2.2 Samples already in a dispersion . 8
8 Determination of methods . 8
9 Structural characterization using optical microscopy, SEM, AFM and Raman spectroscopy 8
10 Structural characterization using TEM . 9
11 Surface area determination using the BET method .10
12 Graphene lateral size and number fraction calculation .10
Annex A (informative) Rapid test for graphitic material using Raman spectroscopy .11
Annex B (informative) Structural characterization protocol using SEM, AFM and Raman
spectroscopy .14
Annex C (informative) Structural characterization using TEM .29
Annex D (informative) Lateral size and number fraction calculation .36
Annex E (informative) Brunauer–Emmett–Teller method .43
Annex F (informative) Additional sample preparation protocols — Silicon dioxide on
silicon wafer preparation and cleaning .47
Bibliography .48
ISO/TS 21356-1:2021(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that
are members of ISO or IEC participate in the development of International Standards through
technical committees established by the respective organization to deal with particular fields of
technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives or www .iec .ch/ members
_experts/ refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC
list of patent declarations received (see patents.iec.ch).
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
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World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html. In the IEC, see www .iec .ch/ understanding -standards.
This document was prepared jointly by Technical Committee ISO/TC 229, Nanotechnologies, and
Technical Committee IEC/TC 113, Nanotechnology for electrotechnical products and systems.
A list of all parts in the ISO/IEC 21356 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html and www .iec .ch/ national
-committees.
iv © ISO 2021 – All rights reserved

ISO/TS 21356-1:2021(E)
Introduction
Due to the many superlative properties of graphene and related 2D materials, there are many
application areas where these nanomaterials could be disruptive, areas such as flexible electronics,
nanocomposites, sensing, filtration membranes and energy storage.
There are barriers to commercialisation that are impeding the progress of products containing
graphene, which need to be overcome. One of these crucial barriers is answering the question “What
is my material?”. End-users of the raw materials containing graphene should be able to rely on the
advertised properties of the commercial graphene on the global market, instilling trust and allowing
worldwide trade. Reliable and repeatable measurement protocols are required to address this challenge.
This document provides a set of flow-charts for analysts to follow in order to determine the structural
properties of graphene from powders and liquid dispersions (suspensions). Initially, a quick check
should be undertaken to determine if graphene and/or graphitic material is present. If it is, then further
detailed analysis is required to determine if the samples contain a mixture of single-layer graphene,
bilayer graphene, few-layer graphene, graphene nanoplatelets and graphite particles. Depending on
the methods used, the samples are typically analysed after deposition on a substrate. The document
describes how to assess what measurements are required depending on the type of sample and includes
decision trees and flow diagrams to aid the user. This document describes a selected set of measurands
that are needed, namely:
a) the number of layers/thickness of the flakes;
b) the lateral dimensions of flakes;
c) layer alignment;
d) the level of disorder;
e) the estimated number fraction of graphene or few-layer graphene;
f) the specific surface area of the powder containing graphene.
The above physical properties of the material can change during its processing and lifetime, for example,
the samples can become more agglomerated, obtain different surface functionalities. The above
measurand list for the initial material defines their inherent characteristics that, along with the chosen
manufacturing processes, will determine the performance of real-world products. Generally, different
material properties can be important in different application areas, depending on the functional role of
the material.
The document provides methods for structural characterization of individual flakes of graphene,
bilayer graphene, graphene nanoplatelets and graphite particles isolated from powders and/or liquid
dispersions. It does not provide methods for determination of whether the powders and/or dispersions
are composed solely of these materials. No recommendation is provided as to when or how often to
measure samples, although it is not expected this would be for every batch of the same material. It is up
to the user to determine when, how often and which characterization routes described in this document
to take. As with all microscopical investigations, care is needed in drawing statistical conclusions
dependant on representative sampling.
A set of annexes provide example protocols on how to prepare and analyse the samples, sources of
uncertainty and how to analyse the data. The methods used are Raman spectroscopy, scanning electron
microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and the
BET (Brunauer–Emmett–Teller) method.
TECHNICAL SPECIFICATION ISO/TS 21356-1:2021(E)
Nanotechnologies — Structural characterization of
graphene —
Part 1:
Graphene from powders and dispersions
1 Scope
This document specifies the sequence of methods for characterizing the structural properties of
graphene, bilayer graphene and graphene nanoplatelets from powders and liquid dispersions using a
range of measurement techniques typically after the isolation of individual flakes on a substrate. The
properties covered are the number of layers/thickness, the lateral flake size, the level of disorder, layer
alignment and the specific surface area. Suggested measurement protocols, sample preparation routines
and data analysis for the characterization of graphene from powders and dispersions are given.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 80004-1:2015, Nanotechnologies — Vocabulary — Part 1: Core terms
ISO/TS 80004-2:2015, Nanotechnologies — Vocabulary — Part 2: Nano-objects
ISO/TS 80004-6:2021, Nanotechnologies — Vocabulary — Part 6: Nano-object characterization
ISO/TS 80004-13:2017, Nanotechnologies — Vocabulary — Part 13: Graphene and related two-dimensional
(2D) materials
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TS 80004-1:2015,
ISO/TS 80004-2:2015, ISO/TS 80004-6:2021, ISO/TS 80004-13:2017 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
graphene
graphene layer
single-layer graphene
monolayer graphene
single layer of carbon atoms with each atom bound to three neighbours in a honeycomb structure
Note 1 to entry: It is an important building block of many carbon nano-objects.
Note 2 to entry: As graphene is a single layer, it is also sometimes called monolayer graphene or single-layer
graphene and abbreviated as 1LG to distinguish it from bilayer graphene (2LG) (3.3) and few-layer graphene
(FLG) (3.4).
ISO/TS 21356-1:2021(E)
Note 3 to entry: Graphene has edges and can have defects and grain boundaries where the bonding is disrupted.
[SOURCE: ISO/TS 80004-13:2017, 3.1.2.1]
3.2
graphite
allotropic form of the element carb
...