Solid-contact polymeric membrane ion-selective electrodes using a covalent organic framework@reduced graphene oxide...

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Solid-contact ion-selective electrodes (SC-ISEs) are crucial for ion detection.
• Developing stable and sensitive SC-ISEs with low potential drift remains a challenge.
• Covalent organic frameworks (COFs) and reduced graphene oxide (rGO) offer unique electrochemical properties.

Purpose of the Study:

• To synthesize and characterize a novel COF@rGO composite for SC-ISE applications.
• To evaluate the performance of a cadmium ion-selective electrode (Cd²⁺-ISE) based on the DAAQ-TFP@rGO composite.
• To assess the stability, reproducibility, and potential drift of the developed SC-Cd²⁺-ISE.

Main Methods:

• Synthesis of the DAAQ-TFP@rGO composite via polycondensation of 1,3,5-triformylphloroglucinol (TFP) and 2,6-diaminoanthraquinone (DAAQ) on rGO nanosheets.
• Fabrication of a solid-contact Cd²⁺-ISE using the DAAQ-TFP@rGO composite as the sensing layer.
• Electrochemical characterization including potentiometric measurements, limit of detection determination, and potential drift analysis.

Main Results:

• The DAAQ-TFP@rGO composite exhibited high capacitance and good redox activity.
• The developed SC-Cd²⁺-ISE showed a Nernstian slope of 29.7 mV/decade and a limit of detection of 6.8 × 10^-8 M.
• The electrode demonstrated excellent stability with a low potential drift of 1.2 μV/h over 70 hours and good reproducibility (standard deviations of 0.28-0.30 mV).

Conclusions:

• The DAAQ-TFP@rGO composite is a highly promising material for constructing advanced SC-ISEs.
• The developed SC-Cd²⁺-ISE offers superior performance characteristics, including stability and sensitivity.
• This composite material holds potential for the development of calibration-free SC-ISEs.