Enhanced visible-light catalytic activity of micro-patterned ZnFe₂O_4/ Fe³⁺-TiO₂ heterojunction composite thin films prepared by photolithography-assisted chemical solution deposition

Micro-patterned ZnFe2O4/Fe3+-TiO2 (ZFO/FTO) heterojunction composite thin films were fabricated by lithography-assisted chemical solution deposition. Their hydrophilicities and photocatalytic activities were investigated in comparison to those of FTO, ZFO and un-patterned ZFO/FTO (UP-ZFO/FTO) films. All micro -patterned ZFO/FTO films present the improved hydrophilicity, and their water contact angles decline with decrease of pattern periods. These films were used to degrade methylene blue (MB) under visible-light irradi-ation. Their visible-light catalytic activity have been enhanced, which increase with decrease of pattern period. Under the synergistic effect of heterojunction interface and micro-pattern surface, the catalytic degradation rate of MB using a ZFO/FTO film with a pattern period of 5 mu m (ZFO-5/FTO) is more than 2 times as that utilizing UP-ZFO/FTO film, and over 3 times as that of FTO film. Furthermore, ZFO-5/FTO film catalyst can be recycled, and its catalytic performance does not decrease with the number of cycles.