Preparation of Polybenzimidazole-Carboxylated Multiwalled Carbon Nanotube Composite for Intrinsic Sensing of Hydrogen Peroxide

A three-dimensional composite was prepared from polybenzimidazole and carboxylated multiwalled carbon nanotubes (PBI-MWCNT-COOH). The composite was used to modify gold (Au) electrodes for hydrogen peroxide (H2O2) detection. The carboxylated nanotubes acted as a reducing agent, reacting with H2O2 to form the nanotube peroxy acid MWCNT-COOOH. The peroxy acid in turn oxidized the imine site of PBI to form PBI N-oxide, which could be electrochemically reduced to PBI, resulting in a current signal proportional to the peroxide concentration. Under optimal conditions, the amperometric response to H2O2 was linear for concentrations from 6.25 μM to 10 mM, with high sensitivity (617.3 μA mM–1 cm–2) and rapid response (2.2 s) at an applied potential of −0.37 V. The sensor also displayed high selectivity and excellent stability.