Substrate and pH-dependent homogeneous electrocatalysis using riboflavin for oxygen reduction

Abstract

Homogeneous, aqueous solutions of the natural compound riboflavin were investigated for their electrocatalytic oxygen to hydrogen peroxide (H₂O₂) reduction performance using cyclic voltammetry and electrolysis. In addition to pH dependencies, interestingly the choice of carbon-based electrode material had a strong impact on the electrocatalytic performance. Therefore, the three electrode materials, glassy carbon, carbon paper (CP), and carbon felt were electrochemically compared and afterwards investigated with scanning electron microscopy. Attributed to the deprotonation of riboflavin, pH = 13 was identified as the best performing condition. Using CP at pH = 13, the addition of riboflavin enhanced the H₂O₂ production by a factor of 14 up to 355 μmol after 6 h at an average faradaic efficiency of around 80%.