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

Fixation of CO 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-CaCl-CaO as electrolyte, soluble GeO as Ge feedstock, conducting substrates as cathode, and carbon as anode. A cathode-anode synergy is verified for coelectrolysis of soluble GeO and in situ-generated CO 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 CO 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 CO fixation to advanced energy materials, and upgraded conversion of carbon bulks to CNTs.