Selective zinc ion detection by functionalised ZnO nanorods with ionophore

Abstract

In this paper, highly dense and well aligned single-crystal zinc oxide nanorods were grown along the c-axis on a gold coated glass substrate using a low temperature aqueous chemical growth approach. The prepared ZnO nanorods were functionalized with plastic membrane coatings containing specific ionophore (12-crown-4) which is highly selective to zinc ions (Zn+2). The electrochemical response of the sensor was found to be linear over a relatively wide logarithmic concentration range from 1 μM to 100 mM. The proposed sensor showed a good linearity with a high sensitivity of ∼35 mV/decade for sensing Zn+2 ions. A fast response time of less than 5 s with a good selectivity, repeatability, reproducibility, and negligible response to common interferents ions such as calcium (Ca2+), magnesium (Mg2+), or potassium (K+), and iron (Fe+3) and copper (Cu+2) was also demonstrated. Moreover, the proposed sensor showed good stoichiometric results for potentiometric titration.