Multi-channel electron transfer induced by polyvanadate in metal-organic framework for boosted peroxymonosulfate activation

Abstract

Catalytic peroxymonosulfate (PMS) activation processes don’t solely rely on electron transfer from dominant metal centers due to the complicated composition and interface environment of catalysts. Herein the synthesis of a cobalt based metal-organic framework containing polyvanadate [V₄O₁₂]⁴⁻ cluster, Co₂(V₄O₁₂)(bpy)₂ (bpy = 4,4’-bipyridine), is presented. The catalyst demonstrates superior degradation activity toward various micropollutants, with higher highest occupied molecular orbital (HOMO), via nonradical attack. The X-ray absorption spectroscopy and density functional theory (DFT) calculations demonstrate that Co sites act as both PMS trapper and electron donor. In situ spectral characterizations and DFT calculations reveal that the terminal oxygen atoms in the [V₄O₁₂]⁴⁻ electron sponge could interact with the terminal hydrogen atoms in PMS to form hydrogen bonds, promoting the generation of SO₅* intermediate via both dynamic pull and direct electron transfer process. Further, Co₂(V₄O₁₂)(bpy)₂ exhibits long-term water purification ability, up to 40 h, towards actual wastewater discharged from an ofloxacin production factory. This work not only presents an efficient catalyst with an electron sponge for water environmental remediation via nonradical pathway, but also provides fundamental insights into the Fenton-like reaction mechanism.