Construction of Cu-bridged Cu2O/MIL(Fe/Cu) catalyst with enhanced interfacial contact for the synergistic photo-Fenton degradation of thiacloprid

Abstract

Cu2O/MIL(Fe/Cu) composite was fabricated via an in-situ Cu-bridging strategy to enhance interfacial synergistic effect of photo-Fenton catalysis for thiacloprid (TCL) degradation. Characterization results showed that: (1) Cu2O was proved to grow on the surface of MIL(Fe/Cu) in Cu2O/MIL(Fe/Cu) composite and display a high BET surface area of 1553 m2/g; (2) Cu2O/MIL(Fe/Cu) reduced band gap from 2.5 to 1.3 eV and extended absorption from UV to visible region; (3) Cu-bridge was proved to promote the intimate interface between Cu2O and MIL(Fe/Cu), which accelerated charge transferred and shortened the binding gap and the reaction pathway from photo-induced electrons to Fenton-generated radicals. As a result, this boosted the redox reaction of Fe2+/Fe3+ and promoted the reversible degree of this catalytic redox ability of MIL(Fe). Catalytic performance exhibited that (1) Cu2O/MIL(Fe/Cu) showed a fast kinetics (2–40 times faster than the state-of-the-art catalysts) and ultra-high mineralization (82.3% within 80 min) for TCL degradation; (2) Cu2O/MIL(Fe/Cu) showed a promising cycling stability due to improved charge transfer ability that could protect Cu2O from photo-corrosion during photo-Fenton reaction; (3) The catalytic performance of Cu2O/MIL(Fe/Cu) was characterized and seven photocatalytic intermediates were identified by both HPLC/MS and Surface Enhanced Raman Spectroscopy. The cyanoimino group in TCL was proved for the first time to be attacked primarily. Moreover, among all the detected intermediates, thiazolidin-2-amine (P6) was found to be the most stable intermediate to be degraded, and it can directly influence the TOC determination during photodegradation process.