Nanocomposites and nanomaterials

Copper-sensitive ion-selective electrode with solid contact based on copper oxide nanoparticles- multiwalled carbon nanotubes-nanopomposite

C. Wardak1*, K. Pietrzak1

1 Department of Analytical Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, Maria Curie-Skłodowska Sq. 3, 20-031 Lublin, Poland
E-mail: *cecylia.wardak@mail.umcs.pl 

Potentiometry with ion-selective electrodes (ISEs) allows to directly determine free ion concentration in aqueous samples. The main advantages of this technique are low costs, speed which samples can be analyzed with, device portability, no sample destruction and the requirement of minimum sample preparation. Among the various types of ISEs, those with solid contact are becoming increasingly popular. In comparison to conventional ISEs they are characterized by unquestionable advantages including small size, simple construction, lower cost of production, and ability to operate in high pressure environments. Moreover they can have various shapes, sizes and can work in any position. Unfortunately solid contact ion-selective electrodes (SCISEs) often exhibited big potential drift and poor reproducibility because of blocked interface between ion-selective membrane with ionic conductivity and electronic conductor.
This paper presents electrodes sensitive to copper (II) ions, in which copper (II) oxide nanoparticles-multi-walled carbon nanotubes (MWCNTs) composite was used as solid contact. In order to investigate the influence of modification of the electrode structure, the selected analytical parameters obtained by means of potentiometric measurements (slope, linearity range, detection limit, potential stability and reversibility) and electrochemical impedance spectroscopy and chronopotentiometry measurements (membrane resistance and charge transfer resistance as well as double layer capacitance) were compared. The use of both copper (II) oxide nanoparticles and their composite with MWCNTs as a solid contact had a positive effect on the operation of the obtained electrodes. Nanocomposite based electrode showed a lower detection limit, better potential stability and reproducibility. It was not sensitive to gases (O2, CO2) and light. In addition no redox response was observed.