The carbon battle characterization of screen-printed carbon electrodes with SPELEC RAMAN

Importance of the Topic

Carbon materials serve as highly attractive electrode surfaces due to their low cost, chemical inertness, low background currents and wide electrochemical potential windows. Characterizing their sp2/sp3 bond distribution and structural order is vital for tailoring electrodes to specific analytical and sensing applications.

Objectives and Study Overview

This application note demonstrates how Raman spectroscopy can be used to differentiate and evaluate the structural properties of various DropSens screen-printed carbon electrodes (SPEs), including unmodified graphite and electrodes modified with single-walled nanotubes, multi-walled nanotubes, ordered mesoporous carbon and carbon nanofibers.

Methodology

Raman spectra were acquired under standardized conditions to analyze the D, G and G′ bands that reflect bond hybridization and material disorder.

• Excitation wavelength: 785 nm laser
• Spectral range: 0–2850 cm⁻¹
• Integration time: 20 s per measurement
• Use of a dedicated Raman cell and probe to position SPEs at optimal focal distance

Instrumentation

• SPELEC RAMAN: integrated spectroelectrochemical system combining a Class 3B 785 nm laser, spectrometer and bipotentiostat/galvanostat
• RAMANPROBE: 785 nm reflection probe for precise light collection from SPE surfaces
• RAMANCELL: black Teflon cell designed for stable placement of screen-printed electrodes
• Screen-Printed Electrodes (DRP-110, DRP-110SWCNT, DRP-110CNT, DRP-110OMC, DRP-110CNF)

Main Results and Discussion

Raman analysis revealed distinct spectral signatures for each electrode type:

• Graphite SPE: strong G band (~1580 cm⁻¹) and minimal D band (~1300 cm⁻¹), indicating a high fraction of sp2 bonds and low disorder
• SWCNT-modified SPE: characteristic radial breathing modes and prominent G band, confirming tubular carbon structure
• MWCNT-modified SPE: elevated D/G intensity ratio reflecting increased defect sites and edge disorder
• Ordered Mesoporous Carbon SPE: broad D and G bands plus a G′ band (~2600 cm⁻¹), indicative of layered pore networks
• Carbon Nanofiber SPE: intermediate D/G ratio and spectral features consistent with graphitized fibers

The relative intensities of D and G bands provided quantitative insight into sp2/sp3 ratios and structural disorder across materials.

Benefits and Practical Applications of the Method

• Fast quality control of carbon electrode surfaces
• Informed selection of nanomaterials for electrochemical sensors
• Monitoring of surface modifications during sensor fabrication
• Screening and optimization of SPE production batches

Future Trends and Potential Applications

• Real-time spectroelectrochemical monitoring of electrode reactions
• High-throughput Raman mapping of electrode arrays
• Development of novel carbon composites and doped graphene structures
• Portable Raman-electrochemical platforms for on-site analysis

Conclusion

Raman spectroscopy, particularly when integrated into compact systems like SPELEC RAMAN, offers a powerful, non-destructive approach to characterize and compare a range of carbon-based screen-printed electrodes. This facilitates optimized material selection and reliable performance in electrochemical sensing applications.