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.