Enhanced heterogeneous Fenton-like systems based on highly dispersed Fe⁰-Fe₂O₃ nanoparticles embedded ordered mesoporous carbon composite catalyst

Acceleration of Fe³⁺/Fe²⁺ cycle and simultaneous reduction of particle size with enhanced stability is extremely important for iron-based heterogeneous Fenton catalysts. In this work, Fe⁰-Fe₂O₃ composite nanoparticles embedded ordered mesoporous carbon hybrid materials (Fe⁰-Fe₂O₃/OMC) were rationally designed as efficient heterogeneous Fenton catalysts. Because of the confinement and reduction of OMC, highly dispersed Fe⁰-Fe₂O₃ active species with diameter of ∼8 nm were generated by an optimized carbothermic reduction process. In addition, Fe⁰-Fe₂O₃/OMC possesses ordered mesoporous structure with uniform mesopore, high surface area and pore volume. For comparison, two other catalysts, including solely Fe⁰ nanoparticles supported on ordered mesoporous carbon (Fe⁰/OMC) and solely Fe₂O₃ nanoparticles supported on ordered mesoporous carbon (Fe₂O₃/OMC) were also prepared. The Fenton catalytic performance of synthesized catalysts was evaluated by using H₂O₂ as oxidizing agent to degrade Acid Orange II (AOII). The results show that almost 98.1% of 100 mg L⁻¹ AOII was removed by Fe⁰-Fe₂O₃/OMC in condition of neutral pH and nearly room temperature, which is much higher than those of compared catalysts. The enhanced catalytic activity of Fe⁰-Fe₂O₃/OMC for AOII removal is due to the efficient electron transfer between the Fe⁰ and iron oxide and the accelerated Fe³⁺/Fe²⁺ cycle. The stability and reusability of the catalyst was also investigated, which showed a good performance even after five consecutive runs. The as-synthesized catalyst is proved to be an attractive candidate in heterogeneous Fenton chemistry and practical application.