Zn/Co-ZIFs@MIL-101(Fe) metal–organic frameworks are effective photo-Fenton catalysts for RhB removal

Abstract

Treating dye-contaminated wastewater using the visible light–driven photo-Fenton reaction is beneficial to environmental remediation. This paper reports the synthesis of a novel, highly effective photo-Fenton catalyst, the Zn/Co-ZIFs@MIL-101(Fe) composite, by a facile internal-growth method. The composite, which had an MOF-in-MOF structure, activated H2O2 to decompose RhB, a polluting-dye model, under visible-light illumination. The transfer of the electron–hole pair was synergistically accelerated by the reaction centers of the composite (the MIL-101(Fe) shell and Zn/Co-ZIFs core), which enhanced H2O2 activation. The generated OH, O2−, and 1O2 effectively decomposed RhB. The composite’s catalytic performance was significantly enhanced by the electronic hybridization of its Fe3+, Co2+, and Zn2+ metal centers. Thus, the composite demonstrated a remarkable capability to remove RhB. The composite polymetallic MOFs loaded with 3% Zn/Co-ZIFs prepared by us showed good reusability and water stability, and their morphology and structure did not change significantly after four runs, depending on the iron, cobalt, and zinc metal leaching concentrations 0.134 mg/L, 0.06 mg/L and 0.054 mg/L respectively. This study provides a novel method to construct an Zn/Co-ZIFs@MIL-101(Fe) catalyst with dual reaction centers that enhance the transfer of electron–hole pairs. Our findings inspire the application of MOF-based photo-Fenton catalysts to wastewater treatment and environmental remediation.