Ultralow H₂O₂-Triggered Electron Transfer over Single-Atom Iron Catalysts for Long-Term Recyclable Fenton-Like...

Excessive consumption of hydrogen peroxide (H₂O₂) in Fenton and Fenton-like processes highlights the urgent need for catalytic systems that enable efficient pollutant removal with low H₂O₂ usage. In this study, we design a single-atom iron/graphene oxide (Fe₁-GO) catalyst with an Fe─O─C configuration that facilitates pollutant removal under visible-light (VL) irradiation with minimal H₂O₂ input, while ensuring long-term catalytic stability. Using only 2 mM H₂O₂, the system sustained over 95% removal of carbamazepine (CBZ) across four cycles, exhibiting a high H₂O₂ utilization efficiency of nearly 100% for CBZ mineralization. In situ experimental analyses and density functional theory (DFT) calculations reveal that H₂O₂ triggers the formation of Fe(IV)═O on Fe₁-GO, promoting electron transfer from CBZ to Fe(IV)═O. This process drives H₂O₂ generation via oxygen reduction on Fe atoms, thereby continuously replenishing H₂O₂ in the system. A large-scale continuous-flow reactor incorporating a Fe₁-GO/polyacrylonitrile membrane efficiently removed CBZ over 420 min using only 2 mM H₂O₂. Compared to conventional Fenton processes, this system significantly reduces H₂O₂ and catalyst usage, resulting in a 10-fold decrease in operating costs. This study provides a sustainable strategy for pollutant removal through low-H₂O₂-input, long-term recyclable Fenton-like reactions.