The nature and catalytic reactivity of UiO-66 supported Fe3O4 nanoparticles provide new insights into Fe-Zr dual active centers in Fenton-like reactions

Fe3O4 nanoparticles supported on zirconium-based metal-organic frameworks, UiO-66, were firstly used as a tool for exploring the interaction between dual active centers in Fenton-like reactions. Compared with traditional H2O2/Fe3O4 system, nearly 3 times hydroxyl radicals (HO•) were found in the H2O2/Fe3O4@UiO-66 system at pH 5. Additionally, singlet oxygen (1O2) was also detected in the H2O2/Fe3O4@UiO-66 system. X-ray photoelectron and Mössbauer spectroscopy analyses indicate that the electrons on ≡Fe(II) were directed towards Zr, causing ≡Fe(II) to lose electrons more easily, which facilitates H2O2 reduction. However, 1O2 was formed when superoxide anions (O2•−) lost electrons on the Zr center; these electrons can be transferred to ≡Fe(III), accelerating ≡Fe(III) reduction. These findings reveal that Zr centers can interact with Fe to form dual active centers in Fenton-like reactions. And it also provides a novel strategy to optimize dual active center catalysts for Fenton-like processes in water remediation.