Electrochemical sensing of hydrogen peroxide using a cobalt(III) complex supported on carbonaceous nanomaterials

• A H2O2 sensor was designed using a nanocomposite of cobalt(III) complex and MWCNTs.
• Cobalt(III) complex supported on MWCNTs can furnish direct eletrochemistry.
• The sensor showed a low detection limit and wide linear detection range.
• The cobalt(III)/MWCNTs showed excellent electrocatalytic activity for H2O2 reduction.

Hydrogen peroxide (H2O2) detection was electrochemically performed using a non-enzymatic cobalt(III) complex (2) of an amidomacrocyclic ligand (1). We have characterized the metal complex using analytical techniques such as 1H NMR and ESI-MS and the composite material of the catalyst supported on multiwalled carbon nanotubes (MWCNTs) with XPS and TEM. Using different carbonaceous nanomaterials, varying catalyst:nanomaterial ratio and changing the pendant groups on the ligand moiety of the complex, we found that a dichloro substituent (2a) supported on MWCNTs as the most effective H2O2 sensor. From these studies, a low detection limit (5.0 × 10−8 M) and a wide detection range was obtained. Electrochemical studies indicated 2a and MWCNTs worked synergistically to detect the presence of H2O2. UV/Vis of 2a showed the disappearance of a peak at 500 nm and the emergence of a peak at 395 nm after the addition of H2O2 to 2a indicating formation of an intermediate species. 2a was also able to electrochemically determine the concentration of H2O2 present in several commercial products. Hence, 2a shows promising application as a non-enzymatic H2O2 sensor.

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