Pei Lay Yap

Folic acid-derived carbon quantum dots enable dual-mode optical sensing, binary-mixture analysis, and matrix-effect correction for reliable detection of toxic heavy metals in diverse real-water matrices using a green, scalable sensing platform.

Converting dissipated triboelectric mechanical energy into useful chemical work offers an emerging pathway for energy-efficient environmental remediation, yet their integration with continuous chemical processes is still not demonstrated. Here, we present a flow-activated triboelectric catalytic system that converts hydrodynamic mechanical energy into interfacial charge to drive continuous pollutant degradation without external catalysts or chemical oxidants. Polytetrafluoroethylene (PTFE) microparticles are introduced into a coiled flow inverter (CFI), where hydrodynamic shear, particle–wall collisions, and secondary flows continuously generate triboelectric charge and promote interfacial electron transfer. The resulting charge separation activates dissolved oxygen to produce reactive oxygen species (ROS), enabling methylene blue (MB) degradation through a mechanically driven catalytic pathway. Results showed 90% MB degradation during 30 h of continuous operation, preserving 73% of its initial activity after six regeneration cycles and achieved 80% pollutant removal in real river water, demonstrating robust operation under complex aqueous conditions. Kinetic analysis revealed biphasic degradation behavior, while radical-scavenging experiments identified hydroxyl and superoxide radicals as the dominant reactive species that is supported by density functional theory calculations. The presented flow-enabled mechanochemical approach where hydrodynamic mechanical energy is directly converted into interfacial electrical and chemical activity, provides a catalyst and oxidant-free approach for continuous environmental remediation

Reliable characterization and quality control of manufactured graphene-related 2D materials are essential for defining structure-property relationships and enabling their broader industrial adoption. However, the robust identification and quantification of chemical functional groups in functionalized graphene remain significant analytical challenges. Conventional spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX), primarily provide qualitative or elemental information and generally lack the sensitivity and quantitative capability required for metrologically robust assessment of functionalization. Here, we systematically evaluate thermogravimetric analysis (TGA) as a complementary analytical method for probing chemical functional groups in functionalized graphene materials. A series of graphene samples functionalized with oxygen-, sulfur-, and nitrogen-containing groups was investigated, revealing distinct and reproducible mass-loss profiles associated with the thermal decomposition and oxidation of specific functional moieties bound to the graphene framework. Correlation of these thermal signatures with comprehensive structural and chemical characterization enables the assignment, differentiation, and quantification of functional groups with improved reliability. This TGA-based approach offers a cost-effective, scalable, and high-throughput pathway toward quantitative functional group analysis, supporting improved comparability, quality control, and standardization of graphene materials. The methodology provides new insights into graphene functionalization and supports its deployment in biomedical, energy storage, catalysis, sensors, coatings, and nanocomposite applications.

Graphene-related materials (GRMs) possess exceptional electrical, mechanical, thermal, and surface properties, offering significant potential across broad sectors and applications in electronics, energy storage, composites, and environmental technologies. Despite extensive investment in academic research and translation, large-scale industrial adoption of GRMs remains slower than projected. This review systematically analyzes the global graphene manufacturing landscape using available data from 100 commercial producers, with a focused evaluation of manufacturing technology, types and forms of produced GRMs, raw material sources, product forms, industrial quality control and characterization practices. Graphite-based production routes, particularly graphene oxide (GO) and reduced graphene oxide (rGO), dominate in the market due to their scalability and cost advantages. However, substantial inconsistencies in the quality of produced GRMs, characterization and standardization depth, analytical evidence, and technical data sheets (TDSs) remain widespread. A SWOT (strengths, weaknesses, opportunities and threats) analysis of emerging graphene in the industry highlights technological maturity and expanding market demand but reveals critical weaknesses and challenges in quality, standardization and cost–performance alignment. Overall, quality of manufactured materials, quality control transparency, and standardization rather than material manufacturing limitations emerge as the primary barriers to the widespread commercial realization of graphene.

Standardisation of data collection and analysis is essential to enable commercialisation of 2D materials in a wide range of technologies. Selected area electron diffraction (SAED) in the transmission electron microscope (TEM) is one of the key methods for distinguishing monolayer from bilayer and few-layer graphene by comparing the 1st and 2nd order diffraction spot intensities. Yet there are many factors that can affect the reliability of data collection and interpretation, causing the measurement of monolayer samples to deviate from the literature boundary condition of I{-2110}/I{1-100}<1 for monolayer graphene. Here we present the results of a large interlaboratory SAED comparison study, where 15 international laboratories measured and analysed nominally identical samples of chemical vapour deposited (CVD) graphene. Large variations were observed in the measured ratios of diffraction spot intensities, with the largest variance associated with poor quality SAED data resulting from poor specimen handling and storage. To inform the reliable determination of monolayer thickness from SAED patterns we provide a description of best practice for specimen handling, TEM operation, data collection and analysis. This work was undertaken within VAMAS Technical Working Area (TWA) 41: Graphene and related 2D materials - Project 9, the results of which have been directly incorporated into ISO/TS 21356-2 for the characterisation of graphene sheets. We find that when this methodology is followed, monolayer graphene can be distinguished from bilayer or thicker material with high confidence where analysis of a single SAED pattern gives I{-2110}/I{1-100}<1.2, even in the absence of precise specimen tilting.

Graphene oxide (GO), having diverse oxygen functional groups, including carboxyl, hydroxyl, carbonyl, and epoxy groups, is a significant graphene-related 2D material (GR2M) essential for various applications. The quantification of these functional groups traditionally utilizes Boehm acid titration, which, however, does not account for epoxy groups crucial for these applications. Presently, there exists no analytical method enabling quantitative assessment of the concentration of epoxy groups in GO available in the market in different forms such as powders, pastes, and dispersions. This paper presents a new approach employing catalyst-assisted acid-water-based titration to quantify epoxy groups in GO materials. The method's efficacy was validated using a well-characterized reference GO sample and tested on commercially produced GO powders, yielding epoxy group concentrations ranging from 1.15 ± 0.047 to 1.37 ± 0.051 mmol/g with high precision and reproducibility. The method introduces two new quality parameters, including the epoxide index (EI) and the equivalent epoxide weight (EEW) not implemented for GO before. Control measurements with a commercial epoxide material of known epoxide content demonstrated excellent agreement by using the proposed approach. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used for comparative characterizations of epoxide groups in GO samples during titrations.

Graphene-related two-dimensional materials available on the global market are manufactured using various production methods, with significant variations in properties and qualities causing serious concerns for the emerging multi-billion graphene industry. To address the limitations of conventional characterization methods probing the properties of individual graphene particles which may overlook the presence of non-graphene carbon impurities at a large (bulk) scale, this paper presents the refining thermogravimetric analysis as a complementary method for the reliable chemical characterization and quality control of graphene powders. A systematic parametric investigation of key experimental conditions such as sample mass and loading, heating rate, and gas environment and flow rate is performed to identify optimized settings for reliable thermal gravimetric measurements. These optimized conditions are evaluated through a series of comparative characterizations using industrially produced graphene, graphene oxide, and reduced graphene oxide powders, including their common carbon impurities. The ability of this method to provide both qualitative and quantitative analyses for characterizing graphene-related materials is confirmed. The optimized method is finally validated through an International Laboratory Comparison study and subsequently incorporated into a new standard. This low-cost, industry-affordable, and complementary characterization method is expected to enhance the quality control of manufactured graphene materials and make a valuable contribution to the growing graphene industry.