Graphene Raman Analyzer: Carbon Nanomaterials Characterization

Importance of the Topic

Carbon nanomaterials such as graphene, carbon nanotubes, and carbon nanofibers offer exceptional electrical, thermal, and mechanical properties that drive innovation in electronics, energy storage, catalysis, water treatment, and composite materials. Reliable, rapid quality assessment of these materials is crucial to support scalable manufacturing, ensure product consistency, and optimize performance in industrial applications.

Study Objectives and Overview

This study evaluates a high-throughput portable Raman analyzer for at-line and on-line characterization of graphene powder coatings, carbon nanofibers, and carbon black. The primary goals are to demonstrate fast detection of structural features, quantify disorder and layer count in graphene, and identify impurities such as iron oxide in carbon nanofibers.

Methodology and Used Instrumentation

Measurements were performed using B&W Tek’s i-Raman® Pro HT with 532 nm laser excitation delivered via a fiber-optic probe. The spectrometer’s back-thinned, TE-cooled CCD ensured low noise and high throughput. Samples—graphene-coated sheets, carbon nanofiber powders, and carbon black powders—were placed in an aluminum pan under an adjustable probe holder for optimal focus. BWSpec software automated data acquisition, baseline correction (airPLS), Savitzky–Golay smoothing, and calculation of peak intensities, full width at half maximum (FWHM), and intensity ratios (I_D/I_G).

Main Results and Discussion

• Graphene Powders: Six coated sheets exhibit clear D, G, and asymmetric 2D bands. Sample-to-sample variation in I_D/I_G (0.0635–0.4665) and G-band FWHM (14.5–15.7 cm^–1) revealed differences in defect density and crystallinity. Sample #6 displayed the highest disorder (I_D/I_G ≈ 0.47) and a distinct D' shoulder at 1620 cm^–1, indicating extensive defects and multilayer content.
• Carbon Nanofibers and Carbon Black: Four carbon black samples showed typical broad D and G bands without a 2D band, with I_D/I_G between 0.56 and 0.77, reflecting highly disordered structure. Two nanofiber samples exhibited pronounced D-band splitting and G-band asymmetry; average I_D/I_G values were 1.37 and 0.47. Raman peaks at ~213 cm^–1 and ~280 cm^–1 confirmed residual Fe₂O₃ impurity from the synthesis process.

Benefits and Practical Applications

The portable i-Raman Pro HT enables rapid, non-destructive at-line or on-line monitoring of structural quality and impurity content in carbon nanomaterials. Automated BWSpec analyses allow real-time process control, batch consistency checks, and early detection of deviations, reducing waste and improving product reliability in graphene production, composite manufacturing, and catalyst development.

Future Trends and Opportunities

Advances in machine-learning–assisted spectral interpretation and integration of compact Raman probes into continuous production lines will further enhance throughput and predictive maintenance. Combining Raman with complementary techniques (e.g., infrared spectroscopy, X-ray methods) could yield multidimensional process analytics. Expansion into real-time feedback loops will accelerate the industrial adoption of next-generation carbon materials.

Conclusion

This work demonstrates that a portable, high-throughput Raman analyzer can effectively characterize key quality attributes of graphene, carbon nanofibers, and carbon black. The approach provides a cost-effective, user-friendly solution for process monitoring and quality control in large-scale carbon nanomaterial manufacturing.

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