Surficial Functionalization of Monolithic Carbon Electrode via Femtosecond Laser Treatment

A scalable, binder-free carbon disc electrode of desired size and shape has been developed. Laser treatment preserves its conductivity and crystallinity while functionalizing the surface with active groups. These functional groups enable the deposition of metal species and impart superhydrophilic and oleophilic properties, making the electrode suitable for use with various electrolytes. This method enables the mass production of high-performance carbon electrodes.

Carbon materials are promising to fulfill the worldwide need for advanced materials in many areas, particularly in electrochemical applications. However, achieving both high conductivity and surface functionalization in carbon electrodes remains a significant challenge. Herein, a scalable, sustainable, binder-free carbon disc electrode is developed in the desired size and shape. Subsequent femtosecond laser treatment introduces surface functionalization with pyrrolic and pyridinic nitrogen species (up to 12.6 at%, as determined by X-ray photoelectron spectroscopy) while preserving the bulk crystallinity and conductivity of the electrode. The laser-treated surfaces exhibit superhydrophilicity (water contact angle of 0°) and oleophilicity (0° for n-heptane, 25° for n-heptadecane), enabling enhanced interaction with electrolytes and anchoring of metal species like iron ions. Electrochemical impedance spectroscopy confirms minimal resistance (≤10 Ω) in 0.1M KOH, even after functionalization. The functionalized electrodes demonstrate improved stability in oxygen evolution reaction tests, with laser-treated samples showing 300–500 mV higher activity than untreated counterparts when Fe-impregnated. This work establishes a simple, industrial-scale method for creating multifunctional carbon electrodes with tailored surface properties, bridging the gap between material sustainability and electrochemical performance.

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