Novel electroactive surface functionality from the coupling of an aryl diamine to carbon black

The reaction of 1,2-diaminoanthraquinone with Vulcan XC72 carbon in 4 M HCl produces two distinct surface bound anthraquinone species, with formal potentials of ca. −0.03 and −0.19 V vs. SCE. The more positive couple is very stable to electrochemical cycling and has been assigned to the expected benzimidazole linkage. The other wave, which decays over hours of cycling is thought to be due to an amine linkage. This type of linkage also appears to be formed spontaneously when 1,2-diaminoanthraquinone is adsorbed onto Vulcan XC72 from methanol.