Graphene Raman Analyzer: Carbon Nanomaterials Characterization

Importance of the Topic

Graphene and related carbon nanomaterials such as carbon nanotubes, nanofibers, graphite and carbon black exhibit exceptional electrical conductivity, thermal transport and mechanical strength due to their unique two-dimensional and tubular structures. Rapid, non-destructive characterization of these materials is essential for quality assurance and process control in research and large-scale manufacturing.

Aims and Overview of the Study

This application note evaluates the performance of a high-throughput portable Raman analyzer for characterizing various carbon nanomaterials. The goals are to demonstrate rapid detection of structural order, defects and impurities, and to assess suitability for at-line and on-line monitoring of production processes.

Methodology and Instrumentation

Instrumentation Used:

• i-Raman Pro HT portable Raman spectrometer with 532 nm excitation and fiber-optic sampling probe
• Back-thinned CCD detector cooled to –25 °C
• BWSpec software for data acquisition, airPLS background correction, Savitzky–Golay smoothing and automated parameter calculation

Measurement Protocol:

• Graphene-coated sheets: 35 mW laser power, 60 s integration, single acquisition
• Carbon nanofibers and carbon black powders: ~21 mW laser power, 90 s integration, three replicates

Main Results and Discussion

Key Raman features (D, G and 2D bands) were used to evaluate crystallinity, defect density and layer characteristics:

• Graphene powders showed ID/IG ratios ranging from ~0.06 to 0.47. Higher ratios and the presence of a D′ band (∼1620 cm⁻¹) indicated increased disorder and defects. Variations in G-band width and 2D-band asymmetry correlated with layer number and crystallinity.
• Carbon nanofibers exhibited prominent D bands (ID/IG up to ~1.37), reflecting high defect density; asymmetry in the G-band indicated contributions from curved graphene layers within nanotubes.
• Carbon black samples lacked a 2D band and showed high ID/IG ratios (0.55–0.77), confirming their amorphous structure.
• Detection of Raman peaks at ~213 and 280 cm⁻¹ revealed residual Fe₂O₃ hematite in nanofiber samples, highlighting the method’s sensitivity to impurities.

Benefits and Practical Applications of the Method

The portable Raman approach enables fast, reproducible at-line or on-line analysis without complex sample preparation. Automated data processing supports real-time monitoring of material quality, defect levels and impurity detection, facilitating process optimization and consistent product specification.

Future Trends and Applications

Advances in portable Raman instrumentation, integration with manufacturing execution systems and machine-learning-based spectral interpretation will expand capabilities for continuous process control, spatial mapping of defects and multi-parameter quality assessment in emerging carbon-based technologies.

Conclusion

A high-throughput portable Raman analyzer effectively characterizes a range of carbon nanomaterials by extracting critical spectral parameters such as ID/IG ratios, band widths and impurity signatures. This method supports rapid, non-destructive quality control and process monitoring in graphene and carbon nanomaterial production.

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