| Summary: | Mo-doped TiO<sub>2</sub> nanotube arrays are prepared successfully by a combined method of direct current (DC) magnetron sputtering and anodic oxidation. The doping amount of Mo can be modified by changing the number of molybdenum blocks on the Ti target while a Ti−Mo alloy film is prepared by magnetron sputtering on a metal Ti substrate, following a Mo-doped TiO<sub>2</sub> nanotube array grown by anodization. Morphology test shows that the doping of Mo could inhibit the phase transition and growth of crystal of TiO<sub>2</sub>. X-ray photoelectron spectroscopy (XPS) results show that Mo has successfully been embedded in the TiO<sub>2</sub> crystal lattice and mainly exists in the valence states of Mo<sup>6+</sup>. Mo-doping samples show slightly increased visible light absorption as the red shift of TiO<sub>2</sub> absorption edge with the band gap dropping from 3.24 to 3.16 eV with 0.5 at.% Mo doping. The enhanced photocurrent is demonstrated for a 0.5 at.% Mo-doped TiO<sub>2</sub> electrode. Through photoelectric performance testing under UV-visible light irradiation, the nanotube array film with a Mo-doped content of 0.5% produced the maximum photocurrent density, which is about four times the undoped TiO<sub>2</sub> nanotube array film, exhibiting a considerable photoelectric effect gain. The controllable Mo doping TiO<sub>2</sub> nanotube array film prepared by this combining technique is expected as a promising material for efficient applications in photoelectric conversion.
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