Nickel hexacyanoferrate membrane as a coated wire cation-selective electrode

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Ion-selective electrodes (ISEs) are crucial for chemical sensing.
• Nickel hexacyanoferrates offer potential as sensing materials.
• Coated wire electrode (CWE) configuration is explored for ISE development.

Purpose of the Study:

• To develop novel ion-selective electrodes for potentiometric sensing.
• To investigate the effect of alkali metal counter ions in nickel hexacyanoferrates on electrode performance.
• To evaluate the sensitivity and selectivity of the developed electrodes for potassium ion detection.

Main Methods:

• Preparation of nickel hexacyanoferrate-based sensing materials with various alkali metal counter ions (e.g., Cs+, K+, Na+, Li+).
• Fabrication of coated wire electrodes (CWEs) using these materials.
• Potentiometric measurements to assess electrode response towards potassium ions.
• Calculation of selectivity constants using the matched potential method.

Main Results:

• All developed electrodes exhibited a quasi-Nernstian response to potassium ions (K+).
• Electrodes incorporating cesium (Cs+) as the counter cation showed the highest sensitivity.
• Selectivity order for alkali metal cations was determined as Cs+ > K+ > Na+ > Li+.
• Selectivity correlated with the effective dimension of hydrated cations.

Conclusions:

• Nickel hexacyanoferrate-based CWEs are effective for potassium ion sensing.
• The choice of counter ion significantly impacts electrode sensitivity and selectivity.
• Cesium is the optimal counter ion for enhanced potassium ion detection in this system.