Plasma-Catalyzed Sustainable Nanocarbon Production for CO₂ Fixation via Electrified Chemical Looping

Electrified catalytic CO-to-C conversion is promising for scalable negative carbon emissions and green carbon-based energy systems via CO₂–CO–C chemical looping. Yet, current processes face limitations in throughput and economic viability, while conventional electrocatalytic systems often suffer from complexity and cost. Meanwhile, sustainable nanocarbon production via thermal chemical vapor deposition of C_xH_y releases CO₂ and struggles from high temperatures, gas dilution, rapid catalyst deactivation, and inconsistent carbon quality. Here, we report a sustainable CO-to-C strategy using earth-abundant iron oxides as catalysts, integrating the Boudouard reaction, nonthermal plasma, and fluidized-bed operation. This system operates in an electrically driven mode at a reduced temperature of 577 °C, without catalyst deactivation (>11 h) or gas dilution, while achieving a high carbon yield (>229 g_C g_Fe^-1), a synthesis rate exceeding 20 g_C g_Fe^-1 h^-1, and producing highly graphitized carbon nanofibers and/or nanocoils. This demonstrates its industrial potential for sustainable nanocarbon synthesis and CO₂ fixation. Meanwhile, under practical conditions, in situ–formed fluidized conductive carbon induces a unique transition from sparse filamentary discharges to densely distributed fine filaments—an effect not attainable in packed-bed or gliding-arc reactors where discharge instability or insufficient catalyst coupling prevails. This shift enlarges the plasma–catalyst interface, triples electron yield at constant power, and redirects gas activation toward vibrational excitation—enhancing plasma–catalyst synergy (6.7% → 34.6%) and carbon crystallinity (A_D/A_G from 2.1 to ~0.7), without additional energy input or high-temperature post-annealing. The concept of DBD plasma combined with conductive fluidized media offers a generalizable path toward scalable electrification of gas-phase conversion, such as CO₂ fixation, ammonia synthesis, and liquid fuel production.