Effect of molecular structure of quinones and carbon electrode surfaces on the interfacial electron transfer process

Quinones can undergo thermodynamically reversible proton-coupled electron transfer reactions and are being applied as electroactive compounds in aqueous organic batteries. However, the electrochemical reversibility of these compounds is not only affected by their molecular structure, but also by the properties of a carbon-based electrode surface. This study combines experimental and theoretical approaches to understand this dependence. We study the electron transfer kinetics of two synthesized quinone derivatives and two commercially available ones with a glass-like carbon, a highly-ordered pyrolytic graphite and a high edge-density graphite electrode (HEDGE). The electrochemical reversibility is notably improved on the HEDGE, which shows a higher density of defects and presents oxygenated-functional groups at its surface. The electron trans-fer kinetics are controlled by adsorbed species onto the HEDGE. Molecular dynamics simulation and quantum mechanics calculations suggest defects with oxygen-containin...