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

Visible-light-active 3D-TNAs@Ti-MOFs composite electrodes were fabricated by decorating nanoscaled Ti-based metal–organic frameworks on three-dimensional TiO(2) 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 TiO(2) nanotubes. The 3D-TNAs@NH(2)-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@NH(2)-MIL-125, a photoelectro-Fenton (PEF) system was constructed. The influence of H(2)O(2) concentration, solution pH and applied bias potential on TC degradation were explored. The results showed that when pH was 5.5, H(2)O(2) 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@NH(2)-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 TiO(2) nanotubes and NH(2)-MIL-125.