Integrating N and F co-doped TiO2 nanotubes with ZIF-8 as photoelectrode for enhanced photo-electrocatalytic degradation of sulfamethazine

Traditional photoanodes decreased in mass transfer rate via coating powdered catalysts on conductive glass. In this work, we obtained a visible light-driven semiconductor- metal organic frameworks (MOFs) hybrid photo-electrode, which was constructed by electro-anodization and deposition growth process. The ZIF-8/NF-TiO2 photoelectrode was based on hollow TiO2 nanotubes, and ZIF-8 nanoparticles were deposited on the surface of the pyramid-shaped rutile TiO2 substrate after N and F co-doping. Compared with unmodified anatase TiO2, the reaction rate of ZIF-8/NF-TiO2 increased by 21.7 times, and the synergistic factor in the photo-electrocatalytic process could reach to 3.5. The porous structure of ZIF-8, the intrinsic band difference between anatase and rutile TiO2 greatly improved light utilization, and promoted electron-hole separation. The electrode could be easily recycled and exhibit excellent repeatability, and the degradation efficiency almost unchanged after 8 cycles. Moreover, possible degradation pathways and photo-electrocatalytic degradation mechanisms of sulfamethazine were proposed. This progress could bring novel insights for the design of semiconductor-MOFs hybrid photo-electrocatalysts.