Shungite (Mineralized Carbon) as a Promising Electrode Material for Electroanalysis

Area of Science:

• Electrochemistry
• Materials Science
• Geochemistry

Background:

• Amorphous carbonaceous rocks offer potential as natural electrode materials.
• Shungite, a Precambrian rock, exists in various forms with differing compositions.
• Evaluating natural materials for electrochemical applications can lead to cost-effective alternatives.

Purpose of the Study:

• To assess the suitability of noble elite shungite and black raw shungite as electrode materials.
• To compare the electrochemical properties of shungite-based electrodes with a standard glassy carbon electrode (GCE).
• To investigate the influence of shungite's composition and morphology on electrode performance.

Main Methods:

• Physicochemical and electrochemical characterization of noble elite shungite and black raw shungite.
• Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) for morphological and compositional analysis.
• Electrochemical testing using ferro/ferricyanide redox couple to determine electron-transfer kinetics, potential range, and capacitance.

Main Results:

• Noble elite shungite electrodes (EShE) exhibited satisfactory performance, with a high carbon content (~94%) and electrochemical properties similar to GCE.
• Black raw shungite electrodes (BShE) showed poorer performance, with lower carbon content (~63%) and significantly higher double-layer capacitance, attributed to impurities.
• EShE demonstrated a heterogeneous electron-transfer rate constant of 7.8 × 10⁻³ cm s⁻¹, a potential range of ~2.1 V, and low capacitance (~50 μF).

Conclusions:

• Noble elite shungite is a suitable material for fabricating electrodes with performance comparable to commercial glassy carbon electrodes.
• The presence of impurities in black raw shungite negatively impacts its electrochemical properties.
• Shungite-based electrodes, particularly from noble elite shungite, represent a cost-effective and viable alternative for electroanalytical applications.