Carbon materials have a fantastic behavior as electrode surfaces because they are cost-effective, chemically inert, have a low background current and a wide potential window. Although the carbon era seemed to come to an end, the development of new carbon nanomaterials has provided novel applications for carbon in the 21^st century. Physical and chemical properties of these materials depend mainly on their structure, so their characterization is essential to choose the right material for the appropriate applications.

Raman spectroscopy is a very attractive technique for material characterization and allows to know in an effortless way some information about the structure of carbon materials in terms of the sp² and sp³ bonds, and, therefore, about their possible properties. In general, the G band of the Raman spectra (around 1580 cm^-1) could provide information on the fraction of sp² bonds and the D band (around 1300 cm^-1) could provide information on the fraction of sp³ bonds (and some disorder in the structure). In some cases, a G’ band also appears around 2600 cm^-1 that could provide some knowledge on the layered structure of some of these materials.

DropSens screen-printed electrodes (SPEs) are low-cost, disposable devices, which are available with working electrodes fabricated in several carbon materials. Their properties can be studied by Raman spectroscopy as described in this Application Note.

The fabulous, compact and integrated instrument for Raman Spectroelectrochemistry, SPELEC-RAMAN, was used for this Application Note. This instrument integrates in only one box: a spectrometer, a laser source (785 nm) and a bipotentiostat/galvanostat.

Screen-printed electrodes (refs. DRP-110, DRP- 110SWCNT, DRP-110CNT, DRP-110OMC, DRP- 110GPH, DRP-110CNF) were placed in a specific cell for this type of devices (DRP-RAMANCELL) coupled with the DRP-RAMANPROBE, which allows to perform

the Raman measurements of the electrode surface at optimal focal distance. Integration time was 20 s.