Synergistic Effects for Boosted Persulfate Activation in a Designed Fe–Cu Dual-Atom Site Catalyst

Advanced oxidation processes (AOPs) are promising ways for oxidative degradation of organic pollutants. Atomdispersed transition metal-nitrogen-carbon (M-N-C) materials exhibit excellent efficiency in activating peroxide bonds and have been extensively pursued for environmental remediation. However, M-N-C with single atoms suffer from intrinsic performance limit of complicated catalytic reactions due to structural simplicity and lack of synergistic active sites. Herein, derived from Fe/Cu-coordinated zeolitic imidazolate frameworks with molecular-scale cages, a well-designed catalyst featuring Fe-Cu dual-metal sites coordinated with N-doped carbon (Fe/Cu-N-C) was fabricated. Compared to the single-atom iron catalyst (Fe-N-C), Fe/Cu-N-C significantly enhanced the chloramphenicol removal rate from 0.073 to 0.093 min-1 due to the synergistic effects of Fe-Cu dual active site. Furthermore, Fe/Cu-N-C exhibits fantastic reactivity for peroxydisulfate (PDS) activation in a wide pH range (3.1 - 10.3). Density functional theory calculations revealed that Fe/Cu-N is the major active site, where electrons transfer from Cu to Fe ensure the low-valence state of Fe for catalytic oxidation. Besides, the optimization of adjacent Cu-N sites improves the bonding orbital distribution of Fe 3d orbitals and promotes the adsorption and cracking of PDS. These findings reveal the cooperative mechanism of Fe-Cu dual-atom site on PDS activation and develop a promising platform toward environmental purification.