Amorphization engineering of Fe-MOFs for intensified photo-Fenton decontamination

Abstract

Fe-MOFs as the prominent Fenton-like catalysts have garnered enormous attention in wastewater decontamination. Herein, a facile amorphization strategy for Fe-MOFs synthesis was developed under ambient conditions. Distinct from highly-crystalline counterpart, Fe-BDC-W (BDC and W denote the ligand of terephthalic acid and the solvent of water, respectively) exhibited the amorphous characteristics, giving rise to its enlarged specific surface area, enhanced light-harvesting capacity, facilitated separation of photogenerated carriers, increased number of coordinatively unsaturated sites and more importantly, peculiar electron-rich Fe centers. Benefited from these, Fe-BDC-W delivered a markedly improved photo-Fenton catalytic performance towards tetracycline hydrochloride degradation, with K_obs being 0.26 min⁻¹, 2.36 times higher than that of the counterpart. Additionally, Fe-BDC-W exhibited significant superiorities like excellence pH tolerance, robust resistance on environmental matrices and good structural stability. Interestingly, due to the coexistence of the dual excitation pathways in Fe-BDC-W, viz., ligand-to-metal charge transfer and direct excitation of iron-oxo clusters under visible-light irradiation, the electron-rich state of Fe centers could be dynamically maintained, realizing the excellent recyclability in long-term operation. This work not only provides a feasible way to modulating the local electron density of reactive metal centers from the perspective of crystallographic structure, but also gives deep insights into the ameliorated Fenton-like catalytic performance based on directional electron transfer.