TTF-TCNQ Solid Contact Layer in All-Solid-State Ion-Selective Electrodes for Potassium or Nitrate Determination

Abstract

Nowadays, organic donor-acceptor molecules have attracted a lot of scientific attention because of their unique properties and potential applications in various fields. Although tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) is well known charge transfer salt for a long time, the first application of this material as ion-to-electron transducer in ion-selective electrodes is presented. As a proof of concept, potassium-selective and nitrate-selective solid-state electrodes were constructed. Moreover, TTF-TCNQ intermediate layers were fabricated using two organic solvents. Developed potassium sensors displayed a good Nernstian response with a slope of 58.52 mV/decade (10−6–10−1 M K+), whereas the nitrate-selective electrodes showed a sensitivity of −58.47 mV/decade (10−5–10−1 M NO-3). Reproducible standard potentials and low detection limits were observed. Potential stability of studied electrodes was evaluated using current-reversal chronopotentiometry. The capacitance of TTF-TCNQ-contacted electrodes is 255 μF and 629 μF for K+ and NO−3 sensors. The results of measurements conducted reveal that TTF-TCNQ has an appropriate effect on potentiometric sensors performance.