Improving the Mg Sacrificial Anode in Tetrahydrofuran for Synthetic Electrochemistry by Tailoring Electrolyte Composition

Mg-0 iscommonly used as a sacrificial anode in reductiveelectrosynthesis. While numerous methodologies using a Mg sacrificialanode have been successfully developed, the optimization of the electrochemistryat the anode, i.e., Mg stripping, remains empirical. In practice,electrolytes and organic substrates often passivate the Mg electrodesurface, which leads to high overall cell potential causing poor energyefficiency and limiting reaction scale-up. In this study, we seekto understand and manipulate the Mg metal interfaces for a more effectivecounter electrode in tetrahydrofuran. Our results suggest that theionic interactions between the cation and the anion of a supportingelectrolyte can influence the electrical double layer, which impactsthe Mg stripping efficiency. We find halide salt additives can preventpassivation on the Mg electrode by influencing the composition ofthe solid electrolyte interphase. This study demonstrates that, bytailoring the electrolyte composition, we can modify the Mg strippingprocess and enable a streamlined optimization process for the developmentof new electrosynthetic methodologies.

Automated summary

This study investigates the electrochemistry of Mg anodes and the potential passivation issue in reductive electrosynthesis. The results show that the composition of the supporting electrolyte affects the Mg stripping efficiency, and halide salt additives can prevent passivation by influencing the solid electrolyte interphase. By tailoring the electrolyte composition, a streamlined optimization process for new electrosynthetic methodologies can be achieved.