Elo Kibena, Margus Marandi, Väino Sammelselg, Kaido Tammeveski, Bjarke B. E. Jensen, Anders B. Mortensen, Mie Lillethorup, Mikkel Kongsfelt, Steen U. Pedersen, Kim Daasbjerg
Highly oriented pyrolytic graphite (HOPG) and graphene grown on Ni (Ni‐Gra) or Cu (Cu‐Gra) by chemical vapour deposition were modified with thick anthraquinone (AQ) films (7−60 nm) by redox grafting of the pertinent diazonium salt. Glassy carbon (GC) electrodes were used for comparison. The AQ‐modified GC electrodes showed excellent blocking properties towards the Fe(CN)63−/4− redox probe, although it was noted that in the case of Ni‐Gra and Cu‐Gra, the blocking ability depended strongly on the underlying substrate. Oxygen reduction studies revealed good electrocatalytic activity of AQ‐modified HOPG, Ni‐Gra, and Cu‐Gra, compared with the bare electrodes.