Long-Term Stable Reference Electrodes with High-Pressure Tolerance and Salinity-Independence.

Area of Science:

• Electrochemistry
• Materials Science
• Oceanography

Background:

• Accurate electrochemical sensing in marine environments is critical but challenged by reference electrode sensitivity to salinity.
• Existing reference electrodes often suffer from inaccuracies due to variations in salinity and environmental conditions.

Purpose of the Study:

• To design and develop a stable, reliable solid-state reference electrode for marine electrochemical sensing.
• To overcome the limitations of existing electrodes in varying salinity and pressure conditions.

Main Methods:

• Fabrication of a solid-state reference electrode using a P(VdF-co-HFP) polymer matrix.
• Incorporation of SiO2-stabilized 1-methyl-3-octylimidazolium bis(trifluoromethyl sulfonyl)imide ([C8mim+][Ntf2-]) ionic liquid.
• Utilized a SPEEK/[C8mim+][Ntf2-] coated Ag/AgCl substrate for enhanced protection and compatibility.

Main Results:

• The developed electrode exhibited stable potential (<0.7 mV variation) across diverse salinity solutions (seawater, lake water).
• Demonstrated negligible potential drift (0.36 mV/d in DI water, 0.14 mV/d in artificial seawater) over 18 days.
• Maintained stable potential after 67 days of storage and withstood pressures up to 100 MPa.

Conclusions:

• The novel solid-state reference electrode provides a stable reference potential in various aquatic environments, including full ocean depths.
• Its robustness against salinity, ionic strength, and pressure variations makes it highly versatile for oceanographic research.
• This electrode technology has significant potential for advancing marine monitoring and exploration.