LAUSR

This study presents novel chemoresistive reduced graphene oxide–ion-imprinted polymer (IIP–rGO)-based sensors for detection of lead (Pb2+) ions. The ion-imprinted polymer was synthesized by bulk polymerization and modified with a variable amount of rGO incorporated to form an IIP–rGO composite. The amount of rGO in the polymer matrix affected the sensor’s relative response, and 1:3 mass ratio produced excellent results, with a consistent trend as the concentration of Pb2+ ions increased in the solution. The decrease in relative resistance (ΔR/Ro) followed an exponential decay relationship between the ΔR/Ro response and the concentration of Pb2+ ions in aqueous solutions. After solving the exponential decay function, it is observed that the sensor has the upper limit of ΔR/Ro >1.7287 μg L–1, and the limit of detection of the sensor is 1.77 μg L–1. A nonimprinted polymer (NIP)-based sensor responded with a low relative resistance of the same magnitude although the concentration was varied. The response ratio of the IIP-based sensor to the NIP-based sensor (ΔR/Ro)IIP/(ΔR/Ro)NIP as a function of the concentration of Pb2+ ions in the solution shows that the response ratios recorded a maximum of around 22 at 50 μg L–1 and then decreased as the concentration increased, following an exponential decay function with the minimum ratio of 2.09 at 200 μg L–1 but never read 1. The sensor showed excellent selectivity against the bivalent cations Mn2+, Fe2+, Sn2+, and Ti2+. The sensor was capable of exhibiting 90% ΔR/Ro response repeatability in a consecutive test.