Growth of 3D-TNAs@Ti-MOFs by dual titanium source strategy with enhanced photoelectrocatalytic/photoelectro-Fenton performance for degradation of tetracycline under visible light irradiation

Abstract

Visible-light-active 3D-TNAs@Ti-MOFs composite electrodes were fabricated by decorating nanoscaled Ti-based metal–organic frameworks on three-dimensional TiO₂ nanotube arrays (3D-TNAs) prepared by a facile in situ solvothermal method. The photoelectrocatalytic performance of electrode materials was evaluated by degradation of tetracycline (TC) under visible light irradiation. The experiment results show that Ti-MOFs nanoparticles are highly distributed on the top and side walls of TiO₂ nanotubes. The 3D-TNAs@NH₂-MIL-125 solvothermally synthesized for 30 h exhibited the best photoelectrochemical performance compared with 3D-TNAs@MIL-125 and pristine 3D-TNAs. In order to further enhance the degradation efficiency of TC by 3D-TNAs@NH₂-MIL-125, a photoelectro-Fenton (PEF) system was constructed. The influence of H₂O₂ concentration, solution pH and applied bias potential on TC degradation were explored. The results showed that when pH was 5.5, H₂O₂ concentration was 30 mM, and applied bias was 0.7 V, the degradation rate of TC was 24% higher than the pure photoelectrocatalytic degradation process. The enhanced photoelectro-Fenton performance of 3D-TNAs@NH₂-MIL-125 could be attributed to the large specific surface area, excellent light utilization, efficient interfacial charge transfer, low electron–hole recombination rate and high production of ˙OH as the result of the synergistic effect between TiO₂ nanotubes and NH₂-MIL-125.