In situ electrochemical conversion of CO₂ in molten salts to advanced energy materials with reduced carbon emissions.

Abstract

Fixation of CO₂ on the occasion of its generation to produce advanced energy materials has been an ideal solution to relieve global warming. We herein report a delicately designed molten salt electrolyzer using molten NaCl-CaCl₂-CaO as electrolyte, soluble GeO₂ as Ge feedstock, conducting substrates as cathode, and carbon as anode. A cathode-anode synergy is verified for coelectrolysis of soluble GeO₂ and in situ-generated CO₂ at the carbon anode to cathodic Ge nanoparticles encapsulated in carbon nanotubes (Ge@CNTs), contributing to enhanced oxygen evolution at carbon anode and hence reduced CO₂ emissions. When evaluated as anode materials for lithium-ion batteries, the Ge@CNTs hybrid shows high reversible capacity, long cycle life, and excellent high-rate capability. The process contributes to metallurgy with reduced carbon emissions, in operando CO₂ fixation to advanced energy materials, and upgraded conversion of carbon bulks to CNTs.