Characterization of electrodes modified with nanocomposites of cobalt tetraaminophenoxyphthalocyanine, reduced graphene and multi-walled carbon nanotubes

Glassy carbon electrodes or plates were modified with nanocomposites consisting of cobalt tetraaminophenoxyphthalocyanine (CoTAPhPc), reduced graphene oxide nanosheets (rGONs) and multi-walled carbon nanotubes (MWCNTs). The modified electrodes were characterized using cyclic voltammetry, scanning electrochemical microscopy (SECM) and time-of-flight-secondary ion mass spectrometer (TOF-SIMS). The electrocatalytic activity of the modified electrode was tested for detection of L-cysteine. The presence of CoTAPhPc on sequential layers of MWCNT and rGONs resulted in improved detection currents compared to CoTAPhPc alone or when MWCNT/rGONs are mixed in CoTAPhPc-MWCNT/rGONs (mix)-glassy carbon electrode (GCE). CoTAPhPc-MWCNT-GCE (without rGONS) showed higher sensitivity toward l-cysteine as compared to the probes incorporating rGONs with a catalytic rate constant of 4.62 x 10(4) M(-1)s(-1) and a detection limit of 30 nM. The presence of rGONs improved the stability of the electrode.