Use of a Bipolar, Metallic Luggin-Haber Probe for Electrochemical Measurements of Interfacial Potential

The most fundamental aspect of electrochemical measurements is the evaluation of the interfacial potentials. Reference electrodes are the primary means by which these potentials are related to thermodynamic conditions as well as to measurements by others. A true reference electrode has its potentials poised by a redox couple occurring on its surface. The potential of the redox couple is known, thus any measurements using the reference electrode can be related to the hydrogen electrode scale, for example. However, most commercial reference electrodes must be separated from the test solution of interest by a porous frit and/or a Luggin-Haber probe/salt bridge in order to minimize contamination. Nonetheless, some ionic flow is required. This work demonstrates the use of a metal wire to serve as a bridge between a reference electrode compartment and a test solution in a physically distinct container. It is shown that the metal bridge provides a means of making identical potential measurements to that from a salt bridge but without the contamination. The metal bridge is shown to be compatible with a wide range of electrochemical techniques. A framework for understanding the potentials measured as well as the limitations of the approach are discussed.

Automated summary

The most fundamental aspect of electrochemical measurements is the evaluation of the interfacial potentials. Reference electrodes serve as a primary means for relating these potentials to thermodynamic conditions and measurements by others. This work demonstrates the use of a metal wire as a contamination-free bridge between a reference electrode compartment and a test solution. The metal bridge enables identical potential measurements to those made with a salt bridge and is compatible with various electrochemical techniques.