Overall Carbon-neutral Electrochemical Reduction of CO2 in Molten Salts using a Liquid Metal Sn Cathode

Abstract

An overall carbon-neutral CO₂ electroreduction requires enhanced conversion efficiency and intensified functionality of CO₂ -derived products to balance the carbon footprint from CO₂ electroreduction against fixed CO₂ . A liquid Sn cathode is herein introduced into electrochemical reduction of CO₂ in molten salts to fabricate core-shell Sn-C spheres (Sn@C). An in situ generated Li₂ SnO₃ /C directs a self-template formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core-shell structure of Sn@C, a CO₂ -fixation current efficiency higher than 84 % and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO₂ conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO₂ .

Keywords: CO2 Fixation; Electrochemistry; Energy Storage; Liquid Metal Cathode; Molten Salt.