Iron Ion Sensor Based on Functionalized ZnO Nanorods

In this work, we are presenting an iron ion (Fe3+) potentiometric sensor based on functionalized ZnO nanorods with selective ionophore (18 crown 6). Zinc oxide nanorods with a diameter of about 100 to 150 nm and 1 µm in length were grown on gold coated glass. The selective Fe3+ ionophore sensor with highly aligned ZnO nanorods showed high sensitivity, acceptable selectivity, reproducibility and a stable signal response for detecting Fe3+. The potentiometric response of the Fe3+ sensor with functionalized ZnO nanorods versus a Ag/AgCl reference electrode was observed to be linear over a logarithmic concentration range from 10−5 M to 10−2 M. The detection limit of the proposed sensor was about 5 µM, which is lower than the normal blood concentration of Fe3+ which is about 10 µM and can be up to 30 µM. The sensitivity of the proposed Fe3+ sensor was found to be 70.2±2.81 mV/decade with a regression coefficient R2=0.99 and a response time less than 5 s. The functionalized ZnO nanorods sensor with selective iron ionophore has a life time greater than one month and has shown insignificant interference with other ions usually present in the human blood serum. The proposed sensor was used as an indicator electrode for potentiometric titration.