Characterization and electrochemical applications of a carbon with high density of surface functional groups produced from beer yeast

Carbon materials enriched with nitrogen and oxygen surface functional groups were obtained by pyrolyzing strained beer yeast at 750 °C under an inert atmosphere. Physical and surface properties of the carbon obtained were characterized by X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectrometry, and X-ray photoelectron spectroscopy. Results show that the carbon possesses an amorphous structure, a spherical morphology, and a high density of surface functional groups. Electrochemical properties were evaluated by cyclic voltammetry, a galvanostatic charge–discharge technique, and electrochemical impedance spectroscopy. The carbon has 989.65 mAh·g−1 of initial discharge capacity and a stable cycle performance for a Li–C cell. A specific capacitance of 120 F·g−1 was obtained for a single carbon electrode and good cycle performance was achieved for a symmetrical supercapacitor fabricated using this carbon. These carbons derived from strained beer yeast have promising applications in energy storage and conversion systems.