Corrosion Resiliency of Boron-Doped Diamond Electrodes in Molten Salts of Varied Composition

With many space agencies setting their goals for a Mars human landing within the next few decades, the search for a method for oxygen gas (O2) production which can utilize natural resources has been a top priority. In-Situ Resource Utilization (ISRU) is the process of collecting and storing materials from other
astronomical bodies, which would eliminate the need for resources to be sent from Earth. The Fray-Farthing-Chen (FFC) Cambridge process is an electrochemical process that can potentially be applied to ISRU applications. The FFC Cambridge process is an industrial use of electrochemistry that uses calcium chloride (CaCl2) and calcium oxide (CaO) molten eutectics, originally developed to generate pure titanium (Ti) from titanium oxide (TiO2) (O2 is released). However, the same chemistry can be used to generate breathable O2, provided the anode material can withstand the harsh molten conditions. In this project, the corrosion resiliency of boron-doped diamond (BDD) electrodes in molten CaO-CaCl2 was examined. BDD is the most mechanically rigid electrode material available and holds strong promise as an anode in electrochemical cells for bulk electrolysis. The corrosion of BDD was first examined in the CaO-CaCl2 eutectic under static conditions at 900 – 1300 K. Bulk electrolysis was then performed with BDD as the anode material, and corrosion was assessed again. Different magnitudes of current density were applied specifically to identity and verify the mechanism of corrosion in BDD. The application for this research can be applied to ISRU for crucial life support systems such as the creation of breathable oxygen and rocket propellant.