Exsolved catalyst–plasma coupling mitigates the activity–stability–crystallinity trade-off in electrified CO-to-graphitic carbon conversion

Electrified CO 2 –CO–C chemical looping offers a promising route for negative emissions and sustainable carbon manufacturing. However, progress at the CO-to-C step remains limited, as gas-to-carbon conversion often suffers from a persistent trade-off among catalytic activity, catalyst durability, and carbon crystallinity under realistic conditions. Here, we demonstrate that exsolved catalyst–plasma coupling can mitigate this limitation, enabling the concurrent enhancement of catalytic activity, stability, and graphitic carbon formation under near-atmospheric pressure (80 kPa) without noble-gas dilution. In a fluidized-bed dielectric barrier discharge reactor, exsolved Fe/Fe–Mg–O delivers over twofold higher CO-to-C productivity than conventional Fe/MgO (15.8 vs 7.8 g C g Fe ⁻ 1 h⁻ 1 ), sustains activity for >12 h, and yields hollow graphitic nanofibers with high crystallinity ( L c = 13.25 nm, d 002 = 3.39 Å). Mechanistic analysis reveals that socketed Fe/Fe–Mg–O interfaces stabilize the active metal phase against catalyst deactivation, while downsized Fe nanoparticles promote plasma–catalyst coupling and controlled graphitic carbon formation. We further identify plasma-driven metal over-exsolution as a critical failure mode, in which nanoparticle coarsening undermines interfacial socketing, leading to catalyst deactivation and degraded carbon crystallinity. This work establishes exsolution-regulated plasma coupling as a robust catalytic strategy for gas-to-carbon synthesis, mitigating the catalytic activity–stability–carbon-quality trade-off and advancing practical electrified carbon fixation via the CO-to-C pathway. Exsolved Fe/Fe–Mg–O catalyst–plasma coupling alleviates the trade-off among catalytic activity, catalyst stability, and carbon crystallinity, enabling efficient electrified CO-to-graphitic carbon conversion under practical conditions. • Exsolved catalyst–plasma coupling mitigates activity–stability–crystallinity trade-off. • Nonthermal plasma enables electrified CO conversion beyond thermal kinetic limits. • Socketed Fe/Fe–Mg–O interfaces stabilize active Fe against deactivation. • Downsized Fe nanoparticles enhance plasma–catalyst coupling and graphitic growth. • Graphitic carbon synthesis is achieved at 80 kPa without noble-gas dilution.