Synthesis and characterization of carboxylated polybenzimidazole and its use as a highly sensitive and selective enzyme-free H2O2 sensor

A novel polyelectrolyte, poly[N-(1-one-butyric acid) benzimidazole] (PBI-BA), was synthesized and used to fabricate an amperometric hydrogen peroxide (H2O2) sensor. It was found that PBI-BA can be oxidized by H2O2 and produce a current response during electrochemical reduction. This mechanism was used to develop an enzyme-free H2O2 sensor. Under optimal experimental conditions, the sensor showed high reproducibility, selectivity and stability. The stability of the PBI-BA electrode after annealing at 100 degrees C was also studied. Interestingly, the sensitivity of the modified electrode was 15.2% higher than that without heat treatment. The sensor was sensitive toward H2O2 over a linear range from 6.2 mu M to 5.0 mM with a detection limit of 3.1 mu M. Because graphene sheets (Gs) suspend readily in the polyelectrolyte solution, a PBI-BA-Gs/Au electrode was also fabricated, improving the sensor's performance dramatically: this sensor detected H2O2 over a linear range of 2.5 mu M to 5 mM, with a correlation coefficient of 0.998 (n = 5) and a sensitivity of 1056 mu A mM(-1) cm(-2).