Conversion of Bi-Sn Complex to Bi Nanoparticles for the Catalysis of V(II)/V(III) Kinetics

In this work, evidence for ligand formation between Sn and Bi is provided utilizing time-resolved X-ray Absorption and 119Sn Mӧssbauer spectroscopy during the colloidal synthesis of Bi metal nanoparticles (NP) in aqueous suspension. SnCl3- is used as simultaneous reducing and stabilizing agent. Auto-reducible complex formation between Sn and Bi using this approach has not been previously been reported. A distorted pyramidal Bi-SnCl3- complex is found to form on the surface of the Bi metal NP which enables their incorporation into electrostatic layer-by-layer (LbL) assemblies of graphene nanoplatelets. These assemblies are shown to act as bifunctional electrocatalyst to simultaneously suppress capacitance losses associated with the hydrogen evolution reaction (HER) and enhance the activity of the V3+↔ V2+ redox couple. Sustainable aqueous-based colloidal synthesis of Bi metal NP utilizing SnCl3- surface ligands provides a convenient method to introduce Bi into macroscopic electrodes for various electrochemical applications.