Novel direct Z-scheme AgI/N-TiO2 photocatalyst for removal of polluted tetracycline under visible irradiation

In the study, we doped N into TiO2 lattice to narrow its band gap energy. Then, the synthesized N doped TiO2 material was combined with AgI to form AgI/N-TiO2 (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e(-)) in N-TiO2 conduction band tended to combine with the left holes (h(+)) in AgI valence band maintaining h(+) in the valence band of the N-TiO2 and e(-) in the conduction band of the AgI. The remained e(-) and h(+) have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N-TiO2). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N-TiO2 molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.