Carbon dioxide to solid carbon at the surface of iron nanoparticle: Hollow nanocarbons for sodium ion battery anode application

Carbon dioxide (CO₂) is the end product of power utilities, industry, and transportation, and it causes many environmental issues. Direct conversion of CO₂ into carbonaceous materials is attractive approach for carbon capture and utilization technologies. In this study, by applying iron oxide nanoparticles as templates, CO₂ was successfully converted into hollow solid nanocarbons. Because the reactivity of iron species is easily controllable, this process needs a simple mild heat-treatment condition, which is more efficient compared with CO₂ conversion with highly reactive metal species. As an anode material for Sodium Ion Batteries (SIBs), the hollow nanocarbon electrode exhibited high reversible capacity (260 mA h g^-1 at 20 mA g^-1), excellent rate performance (59.6% capacity retention at 20,000 mA g^-1), and cycle stability (84.0% retention after 1200 cycles), which are superior to those of hard carbon and graphite electrodes.