Controlled Carbothermal Shock Fabrication of Unique Double-Layer Core–Shell Fe⁰@Fe₃C@Graphite as an Enhanced, Efficient, and Stable Fenton-Like Catalyst

Iron-carbon materials have emerged as promising heterogeneous Fenton-like catalysts for the removal of emerging organic contaminants. However, their practical applications are substantially hindered by complex preparation procedures and irreversible deactivation of iron centers. Herein, a novel double-layer core–shell catalyst Fe⁰@Fe₃C@Graphite (Fe-CTS-3000) is one-step synthesized by a high-temperature carbothermal shock (CTS) strategy. Fe-CTS-3000 features a unique core–shell structure: the uniform nanoscale zero-valent iron (nZVI) core, the complete and homogeneous Fe₃C interlayer, and the highly defective graphitic carbon shell. With a distinctive structure, Fe-CTS-3000 exhibits exceptional catalytic performance, achieving 99.0% tetracycline (TC) removal efficiency and 69.2% mineralization rate, and remarkable stability with higher than 95.8% removal efficiency over 5 cycles in the Fe-CTS-3000/H₂O₂ Fenton-like system. The defective graphite shell enhances TC adsorption, and the nZVI core effectively activates H₂O₂ and further promote the generation of radicals and nonradicals for TC degradation. The complete Fe₃C interlayer facilitates electron transfer and protects the nZVI core from leakage deactivation. Both radical pathways (•OH, •O₂⁻) and non-radical pathways (¹O₂, electron transfer) contributed to the highly efficient degradation of TC. The study provides a rapid and controllable method for synthesizing highly efficient iron-carbon catalysts from renewable biomass for the Fenton-like degradation of persistent organic pollutants.