Defect-induced in situ electron-metal-support interactions on MOFs accelerating Fe(III) reduction for high-efficiency Fenton reactions

• Published in: Chinese journal of catalysis 2024-06, Vol.61, p.247-258
• Main Authors: Mao, Haifang, Liu, Yang, Xu, Zhenmin, Bian, Zhenfeng
• Format: Article
• Language: English
• Subjects: Defect; Electron-metal-support interactions; Fe3+ reduction; Fenton reaction; NH2-UiO-66
• ISSN: 1872-2067; 1872-2067
• DOI: 10.1016/S1872-2067(24)60047-1

The inefficient reduction of Fe3+ and activation of H2O2 in the Fenton reaction severely limit its application in practical water treatment. In this study, we developed defective NH2-UiO-66 (d-NU) with coordinated unsaturated metal sites by adjusting the coordination configuration of Zr, creating a solid-liquid interface to facilitate Fe3+ reduction and the sustainable generation of •OH from H2O2 activation. The d-NU/Fe3+/H2O2/Vis system demonstrated highly efficient removal of various organic pollutants, with a rapid Fe2+ regeneration rate and exceptional stability over ten cycles. The degradation rate constant of d-NU (0.16112 min–1) was 11 times higher than that of NH2-UiO-66 (NU) (0.01466 min–1) without defects. Characterization combined with density functional calculations revealed that defects induced coordination unsaturation of the Zr sites, leading to in situ electron-metal-support interactions between Fe3+ and the support via Zr–O–Fe bridges. This accumulation of electrons from the unsaturated Zr sites enabled the adsorption of Fe3+ at the solid-liquid interface, promoting the formation of Fe2+ across a wide pH range with a reduced energy barrier. This study introduces a promising strategy for accelerating Fe3+ reduction in the solid-liquid interfacial Fenton process for the degradation of organic pollutants. The defect led to an asymmetric charge density distribution of the Zr site on NH2-UiO-66, promoting the adsorption of Fe3+ on Zr–O and the formation of a Zr–O–Fe bridge bond, which promoted the generation of Fe2+ through in situ electron-metal-carrier interaction (EMSI), and thus exhibited an excellent photo-Fenton activity.