Photocatalytic performance of Cu-doped TiO ₂ nanofibers treated by the hydrothermal synthesis and air-thermal treatment

Series of transition metal-doped TiO ₂ (metal/TiO ₂ ) is prepared by combining the hydrothermal synthesis and air-thermal treatment without any reduction process. The selected transition metal precursors, including Ag, Au, Co, Cr, Cu, Fe, Ni, Pd, Pt, Y, and Zn, were individually doped into TiO ₂ nanofibers to evaluate the photocatalytic degradation activity and photocatalytic hydrogen generation. Consider the photocatalytic performance of these synthesized metal/TiO ₂ under UV-A irradiation, copper doped TiO ₂ nanofibers (Cu/TiO ₂ NFs) was chosen for further study due to its extraordinary reactivity. Systematical studies were spread to optimize the doping concentration and the calcination condition for much higher photocatalytic activity Cu/TiO ₂ NFs. In the photocatalytic degradation test, 0.5 mol%-Cu/TiO ₂ NFs calcined at 650 °C exhibits the highest activity, which is even higher than commercial TiO ₂ -AEROXIDE ^® TiO ₂ P25 under UV-A irradiation. The synthesized 0.5 mol%-Cu/TiO ₂ -650 NFs also have the capability in the photocatalytic hydrogen production. The hydrogen evolution rates are 200 μmol/g·h under UV-A irradiation and 280 μmol/g·h under UV-B irradiation. The density of state calculated by CASTEP for Cu/TiO ₂ indicates that Cu doping contributes to the states near valence band edge and narrows the band gap. The disclosed process in this study is industrial safe, convenient and cost-effective. We further produce a significant amount of TiO ₂ -based catalysts without any hydrogen reduction treatment.