Enhanced photocatalytic activity of TiO2 activated by doping Zr and modifying Pd

A series of TiO2 photocatalysts introduced with Zr and Pd (TiO2–Zr–Pdx) are synthesized via a sol–gel method. It is revealed that Zr4+ ions are doped into TiO2 lattice in the substitutional mode and Pd2+ ions exist as –O–Pd–O– species on the surface of TiO2. The energy level of the substitutional doped Zr4+ ions and –O–Pd–O– surface species are located about 0.15 eV below the conduction band and 0.4 eV above the valence band, respectively. Moreover, the band structure of TiO2–Zr–Pdx can be further adjusted by changing the amount of Pd2+ ions. Owing to the synergistic effect of Pd and Zr, the response is extended into the visible region and the photogenerated charge carriers are separated effectively. Therefore, TiO2–Zr–Pdx samples exhibit improved photocatalytic activity, compared with TiO2–Zr and TiO2–Pd under both UV and Vis irradiation.