Potentiometric/time resolved chronopotentiometric sensing for an all-solid-state ion-selective electrode based on MXene/MWCNTs as solid contact

Solid-contact polymeric membrane ion-selective electrodes (ISEs) have been an attractive tool for potentiometric sensors. Sufficient transducing performance evaluation and multiple potentiometric analysis are critical to evaluate whether the solid contact transducer material used in ISE is promising. Herein, we describe sandwich-like MXene/MWCNTs-based polymeric membrane ISEs with three-readout strategies of potential response, chronopotentiometric response, and transition time response. The MXene/MWCNTs can be readily prepared by the electrostatic self-assembly strategy, which not only prevented the aggregation of MXene nanosheets and facilitated charge-transfer, but also significantly contributed to the large double-layer capacitance and water-layer free from interference. With Ca2+ as a model, two kinds of Ca2+-ISEs based on thermodynamic response and dynamic response by modulating the polymeric membrane components with three readouts were explored. Moreover, the proposed Ca2+-ISEs under different background electrolytes exhibit the similar Nernstian responses in potentiometry, variable super-Nernstian ranges in chronopotentiometry, and the consistent transition time readout. This study offers a facile MXene/MWCNTs transducer to develop a highly reliable polymeric membrane ISE.