Fabrication, characterization and electrochemical response of pitch-derived open-pore carbon foams as electrodes

Abstract

Macroporous carbon foams (Cfoams) were synthesized by the replication process from mesophase pitch precursor and then characterized for electrochemical sensing and electrosynthetic applications. Scanning electron and optical microscopies revealed a uniform macropore size distribution, replicating the characteristics of the leachable NaCl particles used as templating agent. Nitrogen adsorption/desorption isotherms revealed the absence of meso- or microporosity, and the specific surface area was measured to be 0.38 m2 g−1. Mercury intrusion porosimetry offered similar results for the specific surface area, and the pore size distribution was deduced to be in the interval of 80 nm–200 µm. X-ray photoelectron spectroscopy allowed concluding that the pore surface exhibited poor oxygenated functionalization. Cyclic voltammetry depicted a wide potential window for the oxidation and reduction of water, with small pseudo-capacitive process. The electrochemical behaviour of outer-sphere reversible redox couples provided a standard rate constant k° of ca. 0.7 cm s−1, which is slightly superior to that shown using a conventional glassy carbon electrode. Biomolecules such as ascorbic acid, uric acid and dopamine were also examined to shed some light on sensing applications. The viability of regenerating the coenzyme nicotinamide adenine dinucleotide using a rhodium redox complex has also been addressed in order to explore electrosynthetic potentialities.