Potentiometric Detection of Oxygen Based on the Mixed Potential of Zinc

Abstract

A new potentiometric oxygen sensor is proposed, based on the mixed potential of zinc in a chloride electrolyte. Variations in the sensor potential with oxygen concentration are the direct result of changes in the corrosion rate of the zinc electrode due to diffusion-limited reduction of oxygen at its surface. For static concentration measurements, the performance of the new (potentiometric) sensor is essentially equivalent to that of a traditional (amperometric) Clark sensor. For transient measurements, however, the response of the potentiometric sensor can be considerably faster than the analogous amperometric sensor, due to the sensitivity of the potentiometric method to logarithmic (rather than linear) variations in oxygen concentration.

Ultra-Sensitive Potentiometric Measurements of Dilute Redox Molecule Solutions and Determination of Sensitivity Factors at Platinum Ultramicroelectrodes

“…Similarly, in solutions containing no reversible redox couple that can establish the electrode potential, other half reactions combine to produce a zero net current, setting the potential of the electrode to the so-called mixed potential of the system. The concept of the mixed potential system has been largely used in corrosion science and was first introduced by Wagner and Traud. , Others have shown its use in other areas such as reaction kinetics and catalysis. , Additionally, OCP measurements have also been widely applied as sensing techniques for various chemical species. − This group recently used this concept as an ultrasensitive nanoparticle detection method and analysis technique where platinum nanoparticles were detected as they collided with a gold electrode, leading to a stepwise change in the measured OCP toward that of bulk platinum . By invoking the mixed potential system, the magnitude of the observed OCP steps from nanoparticle collision could be reliably predicted …”

Observation of Single Metal Nanoparticle Collisions by Open Circuit (Mixed) Potential Changes at an Ultramicroelectrode

“…Although the concept was initially developed to understand and study corrosion rates, 14 it can be used to study other problems related to electrochemistry, for example, the poisoning effect of arsenic species on Pt electrodes, 15 or the deposition of copper on a Si wafer. 16 So-called mixed potential-based gas sensors for H 2 , 17 O 2 , 18 nitrogen oxides, 19 and ammonia 20 have also been discussed. We discuss the basic principles of the mixed potential as it is employed here and its sensitivity to small changes elsewhere.…”