Polyphenols on Carbon Paper Electrodes: A Fundamental Study for Sustainable Electrochemical Energy Storage

Promoting sustainable electrochemical energy storage can be achieved by employing biosourced organic molecules with redox-active motifs. Studies focusing on developing high-performance energy storage devices based on redox-active organic molecules often lack a clear understanding of the charge transfer mechanisms involving these molecules. Here, we report on a systematic study of the electrochemical behavior of biosourced polyphenols (pyrogallol, catechin, rutin, quercetin, and mangiferin) deposited on carbon paper electrodes in aqueous electrolytes, to gain insight into their charge transfer mechanisms and reveal possible relationships between (supra)­molecular structure-electrochemical properties. We studied the effect on the electrochemical behavior of modified electrodes of mono/divalent metal cations (Li+, Na+, Mg2+, Ca2+, and Zn2+) in the supporting electrolyte. Contact angle measurements were used to investigate the interface of the polyphenols with water and scanning electron microscopy to reveal their supramolecular structures at the surface of the carbon paper electrodes. Electrochemical studies were performed by cyclic voltammetry and electrochemical impedance spectroscopy. As proof of concept, electrodes based on polyphenols and sustainable conductive additives were studied in a three-electrode configuration for supercapacitor applications.