Electrocatalytic behahiour of cobalt tetraamino-phthalocyanine in the presence of a composite of reduced graphene nanosheets and of multi-walled carbon nanotubes

•Conjugates of multi-walled carbon nanotubes and reduced graphene nanosheets were used to modify glassy carbon electrode.•The electrode was further modified with cobalt tetraamino phthalocyanine.•The modified electrode was employed for the detection of paraquat.•A mechanism for paraquat detection using the composite electrodes is proposed.

A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2) was developed in order to minimize the restacking of the latter. The composite was used to modify a glassy carbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). The modified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy were used to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10−8 M towards the detection of paraguat as a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is also proposed in this work.

Graphical abstractA composite of multi-walled carbon nanotubes, reduced graphene nanosheets and cobalt tetraamino phthalocyanine was used for electrode modification, resulting in a rough surface as judged by scanning electrochemical microscopy.Figure optionsDownload full-size imageDownload as PowerPoint slide