Microwave Ultrafast Heating on Iron-based Nanogap Catalysts for CO₂ Reduction Coupling with Coke Removal

The persistent challenge of catalytic coke deposition is compounded by conventional regeneration methods like air combustion that are both energy-intensive and emit additional CO₂, contradicting global carbon neutrality objectives. Although using CO₂ to convert coke into CO offers a route to simultaneous catalyst regeneration and CO₂ reduction, its application is constrained by the weak oxidizing capacity of CO₂, especially toward highly graphitized cokes. Herein, we develop a microwave-driven technique that enables efficient coke conversion by anchoring iron nanoparticles onto the coke surfaces within seconds. These nanoparticles can not only catalyze the Boudouard reaction but also construct abundant nanogaps that locally enhance electromagnetic fields, resulting in extreme heating to 1990.4 K while maintaining reactor wall temperatures below 800 K. This approach eliminates the need for extremely thermal-resistant reactor material and fully reactivates iron-based catalysts for cyclic plastic pyrolysis. Moreover, the residual coke after treatment evolves into low-defect CNTs (I_D /I_G = 0.192) outperforming commercial counterparts. Techno-economic and carbon footprint analyses confirm the feasibility of a net-zero emission plant, in which captured CO₂ from utility systems is recycled as an oxidant for coke removal, offering a sustainable pathway for coke management and carbon utilization in chemical industries.