Preferential electrosorption of cobalt (II) tetra-aminophthalocyanine at single-wall carbon nanotubes immobilized on a basal plane pyrolytic graphite electrode

This communication describes the preferential electrosorption of cobalt (II) tetra-aminophthalocyanine (CoTAPc) (rather than the expected electropolymerisation) onto a SWCNT immobilized on a basal plane pyrolytic graphite electrode (BPPGE). Cyclic voltammetric and electrochemical impedance spectroscopic data revealed that the electrosorbed CoTAPc is highly stable, well organized with comparable electron-transfer rate constant in ferricyanide solution (kapp ∼ 6 × 10−5 cm s−1 order) to that of the SWNCT. Electrochemical kinetics of the electrosorbed CoTAPc yielded ks of 0.169 s−1 and 832.2 s−1 for the cathodic and anodic reactions, respectively, indicative of different rate-determining steps for the cathodic and anodic reactions. Strong π-stacking interactions between CoTAPc and the sidewalls of the SWCNTs, with possible synergistic covalent interactions, are explained as responsible for the preferential electrosorption process. Both BPPGE-SWCNT-CoTAPc(ads) and BPPGE-SWCNT showed comparable electrocatalytic responses towards the detection of 2-(diethylamino) ethanethiol (DEAET).