Conversion of a Bi-Sn complex to Bi nanoparticles for the enhancement of V(ii)/V(iii) redox kinetics

In this work, evidence for ligand formation between Sn and Bi during the colloidal synthesis of Bi metal nanoparticles (NP) in an aqueous suspension is provided utilizing time-resolved X-ray absorption and(119)Sn Mossbauer spectroscopy. SnCl(3-)is used simultaneously as a reducing agent and stabilizing agent. Auto-reducible complex formation between Sn and Bi using this approach has not been previously reported. A distorted pyramidal Bi-SnCl(3-)complex is found to form on the surface of the Bi metal NP which enables its incorporation into electrostatic layer-by-layer (LbL) assemblies of graphene nanoplatelets. These assemblies are shown to act as a bifunctional electrocatalyst to simultaneously suppress capacitance loss associated with the hydrogen evolution reaction (HER) and enhance the activity of the V3+<-> V(2+)redox couple. Sustainable aqueous-based colloidal synthesis of Bi metal NPs utilizing SnCl(3-)surface ligands provides a convenient method to introduce Bi into macroscopic electrodes for various electrochemical applications.