UV and visible light synergetic photodegradation using rutile TiO₂ nanorod arrays based on a p-n Junction

Herein, we report a photocatalytic heterojunction device of rutile TiO₂ nanorod arrays based on a p-n silicon junction (TiO₂@PN) and its full absorption of ultraviolet and visible light for synergistic photodegradation. The fabricated TiO₂@PN had excellent photocatalytic degradation of methyl orange (MO) under irradiation of a 300 W Xe lamp, and its pseudo-first-order rate constant k was 0.221 h^-1, which was greatly higher than that for TiO₂ nanorod arrays based on an n-p silicon junction (TiO₂@NP, 0.078 h^-1) and glass (TiO₂@G, 0.032 h^-1). The higher photocatalytic performance of TiO₂@PN could be attributed to the fact that the photovoltage (PV) of the p-n junction promotes separation of the electron-hole pairs of the TiO₂, and the holes are thus left within the TiO₂ nanorods to produce a strong oxidant of hydroxyl radicals (˙OH). Moreover, this heterojunction device could be easily fabricated in a large size for easy recovery and recycling, which shows its promise in the solar-driven degradation of environmental pollution.