Green electrode for Pb2+ sensing based on the Nafion-graphene/CNT composite

Bismuth-film electrodes (BFEs) have been used as an alternative to replace mercury electrodes for the determination of heavy metals since 2000s. A Nafion-modified graphene/carbon nanotube composite deposited with Bi on the screen-printed electrode (SPE, denoted as Nafion-G/CNT-BiSPE) is developed for the determination of trace lead in this work. Five factors, including Bi deposition time, concentration of Nafion, pH, pre-concentration time, and pre-concentration potential are investigated to gain a basic understanding for the complicated influences of these main factors on the current response of lead-ion sensing. The result shows that the current response of Pb²⁺ on Nafion-G/CNT-BiSPE is about 50 times of that on BiSPE due to the rough surface of graphene/CNT. The influences of the pH value and the concentration of Nafion on the sensitivity of Pb²⁺ are very obvious.