IEC TS 62607-6-21:2022

IEC TS 62607-6-21
®

Edition 1.0 2022-09
TECHNICAL
SPECIFICATION

colour
inside


Nanomanufacturing – Key control characteristics –
Part 6-21: Graphene-based material – Elemental composition, C/O ratio: X-ray
photoelectron spectroscopy
IEC TS 62607-6-21:2022-09(en)

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IEC TS 62607-6-21

®


Edition 1.0 2022-09




TECHNICAL



SPECIFICATION









colour

inside










Nanomanufacturing – Key control characteristics –

Part 6-21: Graphene-based material – Elemental composition, C/O ratio: X-ray

photoelectron spectroscopy


























INTERNATIONAL

ELECTROTECHNICAL


COMMISSION





ICS 07.120; 07.030 ISBN 978-2-8322-5700-5




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® Registered trademark of the International Electrotechnical Commission

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– 2 – IEC TS 62607-6-21:2022  IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 General terms . 7
3.2 Key control characteristics measured in accordance with this document . 9
4 General . 10
4.1 Measurement instrument . 10
4.2 Calibration of measurement instrument . 10
4.3 Charge control . 10
4.4 Quantitative analysis . 11
5 Measurement procedure . 12
5.1 Sample preparation . 12
5.2 Measurement conditions . 12
5.3 Measurement procedure . 12
6 Data analysis . 13
7 Uncertainty estimation . 13
8 Measurement report . 13
8.1 General . 13
8.2 Test sample identification . 13
8.3 Ambient conditions. 13
8.4 Instrumental information . 14
8.5 Measurement specific information . 14
8.6 Measurement results . 14
Annex A (informative) Relative sensitivity factors . 15
A.1 Overview. 15
A.2 Elemental relative sensitivity factors . 16
A.2.1 General . 16
A.2.2 Pure-element relative sensitivity factors . 16
A.2.3 Elemental relative sensitivity factors from measurements with
compounds . 16
A.2.4 Set of elemental relative sensitivity factors . 16
Annex B (informative) Discussion about the influence of surface contamination . 17
B.1 Sampling depth . 17
B.2 Test study of surface contamination . 18
Annex C (informative) Case study for GNP . 20
C.1 Test sample . 20
C.2 Measurement results using XPS . 20
Annex D (informative) Case study for GO . 24
D.1 Test sample . 24
D.2 Measurement results . 24
Bibliography . 26

Figure 1 – Illustration of XPS peak measured . 11

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IEC TS 62607-6-21:2022  IEC 2022 – 3 –
Figure 2 – Digital photos of test samples as pressed pellet of graphene powder on
different substrates . 12
Figure B.1 – Schematic diagram of sampling depth and XPS spectra . 17
Figure B.2 – Data distribution of relative abundance of C 1s at five test positions
through long-time vacuum desorption treatment . 18
Figure B.3 – XPS spectra of C 1s through thermal desorption of different temperatures
for 1 h . 19
Figure C.1 – Morphologies of GNP sample . 20
Figure C.2 – Survey spectrum of GNP test sample . 21
Figure C.3 – XPS spectra of the main elements of C 1s, O 1s, N 1s, Cl 2p and S 2p
peaks in GNP test sample . 22
Figure C.4 – Data distribution of relative abundance of C, O, and N elements and C/O
ratio of eleven test positions in GNP test sample . 23
Figure D.1 – Data distribution of relative abundance of C, O, S and N elements and
C/O ratio of twelve test positions in GO test sample . 25

Table 1 – Reference values for the peak positions on the binding-energy scale, E . 10
ref n
Table B.1 – Relative abundance of C 1s at different times of vacuum desorption . 19
Table B.2 – Relative abundance of C 1s through vacuum desorption under different
temperatures for 1 h . 19
Table C.1 – Relative abundance of main elements and C/O ratio in GNP test sample . 23
Table D.1 – Relative abundance of main elements and C/O ratio in GO test sample . 24

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– 4 – IEC TS 62607-6-21:2022  IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

NANOMANUFACTURING – KEY CONTROL CHARACTERISTICS –

Part 6-21: Graphene-based material – Elemental composition,
C/O ratio: X-ray photoelectron spectroscopy

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 62607-6-21 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/607/DTS 113/630/RVDTS

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

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IEC TS 62607-6-21:2022  IEC 2022 – 5 –
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts of the IEC TS 62607 series, published under the general title
Nanomanufacturing – Key control characteristics, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
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contents. Users should therefore print this document using a colour printer.

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– 6 – IEC TS 62607-6-21:2022  IEC 2022
INTRODUCTION
Graphene has unique electrical, thermal and mechanical properties and has wide potential
industrial application, especially in the electronics industry: batteries, integrated circuits, high-
1
frequency electronics, displays, etc. [1], [2], [3], [4], [5] . The content of main elements,
especially oxygen element and the ratio of carbon to oxygen are the significant parameters
influencing the electronic and thermal application performance of graphene materials [3]. The
main elements in graphene materials include carbon (C), oxygen (O), nitrogen (N), sulfur (S),
chloride (Cl), and silicon (Si). The C/O ratio is a key parameter to identify the type of graphene
or graphene-oxide (GO), and reflects directly the degree of reduction and product quality of
reduced graphene oxide (rGO). Because of multiple different production processes and
manufacturers for graphene powder, the main elemental composition and C/O ratio are also
different. For the development of industrial application, a standard measurement method with
reliability, accuracy and reproducibility needs to be established. The X-ray photoelectron
spectroscopy (XPS) technique can measure multiple elements simultaneously and obtain
accurately the relative abundance of each element in a test sample [6], [7].
The purpose of this document is to provide an optimized preparation, measurement and
analysis procedure for graphene powder, to enable accurate and quantitative determination of
the C, O, N, S, Cl, Si elements and C/O ratio using the XPS technique.
This document has been developed based on study in VAMAS Technical Working Area 41 (TWA
41).


_____________
1
 Numbers in square brackets refer to the Bibliography.

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IEC TS 62607-6-21:2022  IEC 2022 – 7 –
NANOMANUFACTURING – KEY CONTROL CHARACTERISTICS –

Part 6-21: Graphene-based material – Elemental composition,
C/O ratio: X-ray photoelectron spectroscopy



1 Scope
This part of IEC TS 62607 establishes a standardized method to determine the chemical key
control characteristics
– elemental composition, and
– C/O ratio
for powders of graphene-based materials by
– X-ray photoelectron spectroscopy (XPS).
The elemental composition (species and relative abundance) is derived by the elemental
binding energy and integral peak area at corresponding portion of XPS spectrum.
– The elemental composition refers to main elements in graphene powders, typically including
carbon (C), oxygen (O), nitrogen (N), sulfur (S) , chloride (Cl) and silicon (Si).
– This document is applicable to graphene powders consisting of graphene, bilayer
graphene (2LG), trilayer graphene (3LG), few-layer graphene (FLG), graphene
nanoplate (GNP), reduced graphene oxide (rGO), graphene oxide (GO), and functionalized
graphene powders.
– Typical application areas are the microelectronics and thermal management industries, e.g.
batteries, integrated circuits, high-frequency electronics. This document can be used by
manufacturers in research and development and by downstream users for product selection.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 General terms
3.1.1
graphene
graphene layer
single-layer graphene
monolayer graphene
single layer of carbon atoms with each atom bound to three neighbours in a honeycomb
structure

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– 8 – IEC TS 62607-6-21:2022  IEC 2022
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) and few-layer graphene (FLG).
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 [8], 3.1.2.1]
3.1.2
graphene-based material
GBM
graphene material
grouping of carbon-based 2D materials that include one or more of graphene, bilayer graphene,
few-layer graphene, graphene nanoplate and functionalized variations thereof as well as
graphene oxide and reduced graphene oxide
Note 1 to entry: "Graphene material" is a short name for graphene-based material.
3.1.3
bilayer graphene
2LG
two-dimensional material consisting of two well-defined stacked graphene layers
Note 1 to entry: If the stacking registry is known, it can be specified separately, for example, as "Bernal stacked
bilayer graphene".
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.6]
3.1.4
trilayer graphene
3LG
two-dimensional material consisting of three well-defined stacked graphene layers
Note 1 to entry: If the stacking registry is known, it can be specified separately, for example, as "twisted trilayer
graphene".
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.9 ]
3.1.5
few-layer graphene
FLG
two-dimensional material consisting of three to ten well-defined stacked graphene layers
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.10 ]
3.1.6
graphene oxide
GO
chemically modified graphene prepared by oxidation and exfoliation of graphite, causing
extensive oxidative modification of the basal plane
Note 1 to entry: Graphene oxide is a single-layer material with a high oxygen content, typically characterized by
C/O atomic ratios of approximately 2,0 depending on the method of synthesis.
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.13 ]
3.1.7
reduced graphene oxide
rGO
reduced oxygen content form of graphene oxide

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IEC TS 62607-6-21:2022  IEC 2022 – 9 –
Note 1 to entry: rGO can be produced by chemical, thermal, microwave, photo-chemical, photo-thermal, microbial
or bacterial methods, or by exfoliating reduced graphite oxide.
Note 2 to entry: If graphene oxide was fully reduced, then graphene would be the product. However, in practice,
3 2
some oxygen containing functional groups will remain and not all sp bonds will return back to sp configuration.
Different reducing agents will lead to different carbon to oxygen ratios and different chemical compositions in reduced
graphene oxide.
Note 3 to entry: It can take the form of several morphological variations such as platelets and worm-like structures.
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.14 ]
3.1.8
graphene nanoplate
graphene nanoplatelet
GNP
nanoplate consisting of graphene layers
Note 1 to entry: GNPs typically have thickness of between 1 nm to 3 nm and lateral dimensions ranging from
approximately 100 nm to 100 µm.
[SOURCE: ISO/TS 80004-13:2017 [8], 3.1.2.11 ]
3.1.9
X-ray photoelectron spectroscopy
XPS
method in which an electron spectrometer is used to measure the energy distribution of
photoelectrons and Auger electrons emitted from a surface irradiated by X-ray photons
Note 1 to entry: X-ray sources in common use are unmonochromated Al Kα and Mg Kα X-rays at 1 486,6 eV and
1 253,6 eV, respectively. Modern instruments also use monochromated Al Kα X-rays. Some instruments make use
of various X-ray sources with other anodes or of synchrotron radiation.
[SOURCE: ISO/TS 80004-6:2021 [9], 5.19]
3.1.10
relative elemental sensitivity factor
coefficient proportional to the absolute elemental sensitivity factor, where the constant of
proportionality is chosen such that the value for a selected element and transition is unity
Note 1 to entry: Elements and transitions commonly used are C 1s or F 1s for XPS and Ag M VV for Auger electron
4,5
spectroscopy.
Note 2 to entry: The type of sensitivity factor used should be appropriate for the analysis, for example, of
homogeneous samples or segregated layers.
Note 3 to entry: The source of the sensitivity factors should be given in order that the correct matrix factors or other
parameters have been used.
Note 4 to entry: Sensitivity factors depend on parameters of the excitation source, the spectrometer, and the
orientation of the sample to these parts of the instrument. Sensitivity factors also depend on the matrix being analysed
and in secondary-ion mass spectrometry, this has a dominating influence.
[SOURCE: ISO 18118:2015 [10], 3.2]
3.2 Key control characteristics measured in accordance with this document
3.2.1
elemental composition
species and relative abundance of main elements in the test sample of graphene powder

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– 10 – IEC TS 62607-6-21:2022  IEC 2022
3.2.2
C/O ratio
carbon to oxygen ratio
ratio of relative abundance (atomic fraction) of carbon element to oxygen element in the test
sample of graphene powder
4 General
4.1 Measurement instrument
A modern XPS instrument equipped with monochromated X-rays is required, in order to
measure the relative abundance of each element detected on the surface of a solid test sample.
The sampling depth, D (normal to the surface of the test sample, D = 3λ), is decided by
s s
inelastic mean free path, IMFP(λ). The actual values for the IMFP of electrons in matter are a
function of the energy of the electrons and nature of the sample through which they travel [11].
For organics and polymers, IMFP of C 1s is about 4 nm to 10 nm. Annex B provides a detailed
discussion.
4.2 Calibration of measurement instrument
The XPS instrument should be calibrated prior to measurement. For the calibration of X-ray
photoelectron spectrometers with monochromated Al X-ray sources, use reference materials
(RMs) of Cu, of Au and of Ag. The RMs shall be polycrystalline and of at least 99,8 % purity
metals which, for convenience, are usually in the form of foils typically of an area 10 mm by
10 mm, and 0,1 mm to 0,2 mm thick. The test samples of RMs for instrumental calibration shall
be clean.
The energy resolution of the system should be specified by use of the full width at half maximum
(FWHM) of the silver Ag 3d peak, and the accuracy of the binding energy scale calibration
5/2
as a function of time should also be specified at the energy for the Cu 2p 3/2 or Au 4f 7/2 peaks
from RMs [12], shown in Table 1.
Table 1 – Reference values for the peak positions on the binding-energy scale, E
ref n
E (eV)
ref n
Peak number, n Assignment
Al Kα Mg Kα Monochromatic Al Kα
1 Au 4f 83,95 83,95 83,96
7/2
2 Ag 3d (368,22) (368,22) 368,21
5/2
3 Cu L VV 567,93 334,90 /
3
4 Cu 2p 932,63 932,62 932,63
3/2
NOTE The Ag data included in parentheses are not normally used for calibrations.

4.3 Charge control
In some cases, charge control (the effort to control the buildup of charge at a surface or to
minimize its effect) is needed [13]. The amount and distribution of surface and near-surface
charge for a specific experimental system are determined by many factors, including specimen
composition, homogeneity, magnitude of bulk and surface conductivities, photo-ionization
cross-section, surface topography, spatial distribution of the exciting X-rays, and availability of
neutralizing electrons. Charge buildup occurs along the specimen surface and into the material.
The presence of particles on or different phases in the specimen surface can result in an uneven
distribution of charge across the surface, a phenomenon known as differential charging. Charge
buildup can also occur at phase boundaries of interface regions within the specimen that is

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IEC TS 62607-6-21:2022  IEC 2022 – 11 –
irradiated by X-ray. Some specimens undergo time-dependent changes in the amount of
charging because of chemical and physical changes induced by electrons, X-rays or heat.
For charge control, peak shape is one of the most important parameters to consider in assessing
the effectiveness of the method used. For the measurement of graphene powder defined in this
document, if initial spectrum without any charge control treatment shows peak shift and
broadening, the charge compensation shall be done using an electron flood gun. Low electron
energies (usually 10 eV or less) are used to maximize the neutralization effect and reduce the
number of electron-bombardment-induced reactions.
4.4 Quantitative analysis
The quantitative mass fraction can be analysed from peak area of each element using relative
sensitivity factor (RSF), S. Take the RSF of C 1s as reference, equal to 1, RSFs of other
elements can be calculated in accordance with Annex A. Usually, RSFs of many elements are
readily available within most XPS analysis software packages or from the literature [14], [15].
The peak area of each element can be obtained from integration of the peak defined by the end
points and fitting the peak with an appropriate analytical function after the subtraction of
inelastic background to a measured spectrum by computer software, as in Figure 1.
NOTE The fitting method of C 1s peak on XPS spectrum can be selected appropriately in accordance with test
purpose and test conditions.[7]



a) b)
In a) the vertical lines indicate suitable limits for the construction of a Shirley backgro
...