Eumelanin electrodes in buffered aqueous media at different pH values

Eumelanin, a quinone-based biomacromolecule, is the most common form of the biopigment melanin in the human body. Eumelanin has attracted great interest due to its physicochemical properties, such as metal-ion chelation, free radical scavenging, hydration-dependent (photo) electrical response and redox activity. Investigating the electron transfer properties of eumelanin is key to exploiting the electrochemical energy storage properties of the pigment. In this work, we investigated the redox behavior of chemically controlled eumelanin in NaCH3COO buffer solutions, at different pH values. For our study we used cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge and discharge. Eumelanin, in combination with aqueous electrolytes, provides an attractive case study for eco-designed storage devices based on abundant and environmentally benign materials and interfaces.