The play of bismuth disproportionation: Formation of Bi(I) species during cluster-like electrodeposition mechanism

Abstract

The electrochemistry of main group metal complexes offers fascinating chemical opportunities due to unusual two-electron steps and various intermediate quasi-stable oxidation states. This study explored the electrochemical behaviors of bismuth and antimony halo-thiolate complexes during bias potential cycling in an organic solvent. Our findings reveal critical disproportionation reactions, leading to unique nucleation and growth pathways that enhance the density of electroactive sites for CO₂ reduction to formate—a key reaction for future energy and chemical industries. We present four pieces of evidence supporting a homogeneous disproportionation reaction, which induces a cluster-like deposition mechanism, marking a notable exception in electrodeposition processes. Including antimony complexes in the electrolyte significantly accelerates the formation of Bi(I) intermediates, supposedly via Sb-to-Bi charge transfer. This research advances our understanding of bismuth and antimony electrochemical properties and demonstrates how controlled electrodeposition can optimize electrocatalytic efficiency for applications like CO₂ reduction, contributing to developing more effective and sustainable energy technologies.