The Electrochemical Stability of (Per)chlorate on Present-Day Mars during Dust Activities

Abstract

Perchlorates have been detected by multiple Mars exploration missions, and their possible formation mechanisms have been widely investigated as well. However, their stability associated with Martian dust activity remains poorly understood. On present-day Mars, frequent dust storm activity may trigger electrostatic discharge (ESD) processes, thereby driving active chlorine chemistry at the Martian surface and atmosphere. ESD may be an important process influencing the stability of (per)chlorates on present-day Mars. Here, we exposed NaClO3 and NaClO4 powders to glow-discharge ESD under simulated present-day Martian conditions. Infrared spectra indicate that ESD induces chemical transformation between chlorate (ClO3–) and perchlorate (ClO4–). In situ gas measurements further show the release of reactive chlorine-bearing gaseous species, including ClO2 and Cl2. Ion chromatography of gas-absorption solutions detected dissolved Cl–, further supporting chlorine mobilization from solid (per)chlorate during the ESD process. These results suggest that ESD may promote redox interconversion among chlorine species with different oxidation states. This process deepens our understanding of an active chlorine recycling pathway operating on present-day Mars.