Stable Measurement of Redox Potential of Aqueous Solution Using Platinum Electrode with Continuous Polishing Tool

A performance test for a redox potential measurement of a solution was conducted using continuously polished and untreated platinum working electrodes under an inert condition. The redox potential, measured by a polished electrode, immediately showed steady value which approximately coincided with the equilibrium value of redox reaction between HS- and S42-. Thus, the redox potentials could be controlled by the equilibrium of the redox reaction. On the other hand, the redox potential measured by an untreated electrode was +0.2 V higher than that measured by a continuously polished electrode. The measured redox potential implies that SO42- was the dominant species in the solution. A disagreement of the redox potentials measured by polished and untreated electrodes may have been caused by deactivation of the platinum electrode by the adsorption of sulfuric acid anions.