Respirometric in Situ Methods for Real-Time Monitoring of Corrosion Rates: Part III. Deconvolution of Electrochemical Polarization Curves

Abstract

A highly sensitive respirometric method is presented that allows real-time monitoring of reaction rates involving H 2 and O 2 during electrochemical polarization. The measurement approach is based on simultaneous monitoring of the changes in the total pressure and the O 2 partial pressure inside a closed chamber. Hence, it is possible to quantify the rates resulting from reactions such as HER, ORR and OER as a function of the applied potential. As a result, deconvolution of the net electric current into cathodic and anodic partial reaction rates during electrochemical polarization can be obtained. It was demonstrated that the respirometric monitoring approach can reveal superfluous cathodic reactions from Al during cathodic polarization as well as during anodic polarization of Al and Mg AZ31. Thus, the true metal oxidation rate could be determined from the electric current and the cathodic reaction rates. Furthermore, the rate of the HER during cathodic electrodeposition of Zn was measured. Through respirometric monitoring of Ni and stainless steel at high anodic potentials, the rate of O 2 evolution could be distinguished from electrode oxidation processes. Real-time monitoring of HER, ORR and OER during potentiodynamic polarization Deconvolution of net electric current into anodic and cathodic partial reactions True metal dissolution rates revealed and quantified Current efficiency during metal plating and electrochemical water splitting