A review of the standardized measurement of the characteristics of graphene-based materials

Abstract

Standardization is necessary for the early industrialization of the new materials and technology. It is achieved by having agreed practices for the measurement of properties and other characteristics. The promising use of graphene-based materials in fields like electronics, energy, and composites has resulted in standards for their nomenclature, the measurement of key characteristics, and their specification, etc. Among these, standards for measuring the key characteristics are crucial. The critical parameters are the number of layers, the type and concentration of defects and functional groups, elemental composition, sheet resistance, and carrier mobility. Standards for characterizing these have been analyzed by the International Organization for Standardization Technical Committee in ISO/TC229 and the International Electrotechnical Commission Technical Committee in IEC/TC113. These give details of applicable or preferred samples, the fundamental principles of the techniques, specific precautions, and points for attention in the relevant standards. The pivotal role of the ISO/TC229 and IEC/TC113 standards is considered and challenges and future trends are outlined.

1. Introduction

Graphene has revolutionized materials science by driving breakthroughs and promising applications across different areas because of its extraordinary properties[1–3]. Electronics and wearable device, photonics, biomedical, and energy storage are examples of important graphene-base materials (GBMs) applications[4–5]. Interests in its commercialization increased explosively. Intensive efforts have been made to use graphene in commercial products. It is estimated that the production of GBMs in 2023 was as high as 1.6×109 kg. However, a global survey of 60 graphene samples by adopting well-defined protocol as benchmark revealed critical quality issues[6]. Significantly disparate data in all the measured characteristics indicate information solely provided by the supplier is not convincing or potentially misleading. On one hand, confusion and misinformation are caused by lack of comparability of data originated from different laboratories and producers[6–7]. On the other hand, inconsistency arises from different techniques and/or parameters may adopted for measuring the same characteristic. To facilitate market acceptance, clear and widely accepted standards including detailed measurement protocols for characterizing various graphene-based materials is highly desired. Boggild emphasized that standards are essential for GBMs to leave the starting block in dozens of applications[8]. As a matter of fact, quality metrics and assurance system are imperative for any new materials to be accepted by the market and adopted to industry. It is especially true for GBMs because they are plentiful in physical forms, structure, properties and applications.

Extensive reviews have been published centered on the graphene synthesis, characterization methodologies, and application scenarios[9–11]. However, comprehensive reviews addressing graphene research from the perspective of measurement standardization are notably scarce. Alves et al. reviewed techniques, such as ultraviolet–visible spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, etc., for characterizing graphene, based on what have been reported by literature and standards[12]. Pollard described the advances in the structural and chemical characterization of graphene, and highlighted that standardization will significantly aid global graphene applications[13].

Standards are good practices based on scientifically accepted techniques reported in the literature and industry practices. Measurement standards include specified characteristics and measurands, as well as the applicable measurement methods and procedures. They provide unified crit