Electrocatalysis of oxygen reduction on glassy carbon electrodes modified with anthraquinone moieties

Anthraquinone groups were electrochemically grafted to glassy carbon (GC) electrodes via methylene linker to study the oxygen reduction reaction (ORR) in alkaline medium. Two different anthraquinone derivatives, 2-bromomethyl-anthraquinone or 2-chloromethyl-anthraquinone, were used to modify the GC electrode surface. Several modification conditions encompassing potential cycling and electrolysis at a fixed potential were employed in order to vary the surface concentration of MAQ groups (Γ _MAQ) and to study the dependence of the O₂ reduction behaviour on electrografting procedure. Cyclic voltammetry confirmed the presence of anthraquinone moieties attached to the GC electrode and Γ _MAQ varied in the range of (0.5–2.4)?×?10^?10 mol cm^?2. Oxygen reduction was studied on MAQ-modified GC electrodes of various surface coverage using the rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) methods. The RDE and RRDE results of O₂ reduction reveal that GC/MAQ electrodes show rather similar electrocatalytic behaviour towards the ORR yielding hydrogen peroxide as the final product.