Electrochemical conversion of CO2 into magnetic carbon nanotubes via low-lithium molten salt electrolysis

Abstract

As the global push toward carbon neutrality intensifies, developing efficient CO₂ utilization technologies has become crucial in addressing climate change. Among the various approaches, molten carbonate electrolysis has emerged as a promising method for CO₂ conversion, offering a cost-effective pathway for producing carbon nanomaterials. In this study, we propose a method utilizing an Fe-containing electrode system to electrolyze CO₂ in a Li₂CO₃–BaCO₃ molten salt medium in the absence of externally introduced catalysts, enabling the synthesis of magnetic carbon nanotubes. The effects of current density, electrolysis temperature, and electrolyte composition on the morphology and properties of the resulting carbon products were systematically explored. Under optimized conditions (200 mA cm⁻², 750 °C, 70 mol% Li₂CO₃, 30 mol% BaCO₃), uniform, highly graphitized, and thermally stable multi-walled magnetic carbon nanotubes were successfully synthesized. The products exhibited distinct magnetic properties, which were attributed to the incorporation of iron and the formation of Fe₃C phases, as confirmed by structural and compositional analyses. This approach eliminates the need for conventional catalysts, providing a sustainable, controllable, and scalable strategy for producing magnetic carbon materials, and significantly expands the potential applications of CO₂ electrolysis.