Unusual electrochemical behaviour of AuBr4− in ionic liquids. Towards a simple recovery of gold(iii) after extraction into an ionic liquid

Abstract

The electrochemistry of AuBr₄⁻ complexes extracted into ionic liquids [C₈PYR][NTf₂] or [C₈MIM][NTf₂] saturated with water and gas has been studied by cyclic voltammetry on a glassy carbon macro electrode and by linear voltammetry on a platinum microelectrode. Unlike AuCl₄⁻, the reduction of AuBr₄⁻ to Au(0) is achieved following a one reduction step involving three electrons. The deposition of Au(0) from AuBr₄⁻ is carried out at a potential above that of water, leading to the simple and easy deposition of gold and subsequently to the extraction of AuBr₄⁻ into an ionic liquid.