All-Solid-State Sodium-Selective Electrode with a Solid Contact of Chitosan/Prussian Blue Nanocomposite

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Conventional ion-selective electrodes suffer from potential drift due to liquid junctions.
• All-solid-state designs with solid contacts offer improved potential stability.
• Solid contacts with high capacitance/conductance are crucial for stable potentiometric sensors.

Purpose of the Study:

• To develop and evaluate a chitosan/Prussian blue nanocomposite (ChPBN) as a solid contact layer.
• To enhance the potential stability and performance of all-solid-state sodium ion-selective electrodes.
• To investigate the electrochemical properties of the ChPBN solid contact.

Main Methods:

• Solution-casting of chitosan/Prussian blue nanocomposite (ChPBN) for the solid contact.
• Fabrication of all-solid-state sodium ion-selective electrodes using ChPBN.
• Morphological and chemical characterization of the ChPBN layer.
• Potentiometric measurements to evaluate sensor performance and stability.
• Chronopotentiometry to assess electrical potential stability and capacitance.

Main Results:

• ChPBN forms a macroporous network with embedded Prussian blue nanoparticles.
• The ChPBN layer demonstrated high redox capacitance and fast charge transfer.
• The developed electrode showed a good Nernstian response (52.4 mV/decade) from 10⁻⁴ M to 1 M NaCl.
• Excellent potential stability with minimal drift (1.3 µV/h) over 20 hours was achieved.
• The electrode capacitance was measured at 154 ± 4 µF.

Conclusions:

• Chitosan/Prussian blue nanocomposite is an effective solid contact material for all-solid-state ion-selective electrodes.
• The ChPBN solid contact significantly enhances potential stability and reduces drift.
• This approach offers a promising strategy for developing robust and reliable potentiometric sodium ion sensors.