| Summary: | TiO<sub>2</sub> has been generally studied for photocatalytic sterilization, but its antibacterial activities are limited. Herein, TiO<sub>2</sub> nanospheres with rutile/anatase heterophase junctions are prepared by a wet chemical/annealing method. The large BET surface area and pore size are beneficial for the absorption of bacteria. The rutile/anatase heterojunctions narrow the bandgap, which enhances light absorption. The rutile/anatase heterojunctions also efficiently promote the photogenerated carriers’ separation, finally producing a high yield of radical oxygen species, such as •O<sub>2</sub><sup>−</sup> and •OH, to sterilize bacteria. As a consequence, the obtained TiO<sub>2</sub> nanospheres with rutile/anatase heterojunctions present an improved antibacterial performance against <i>E. coli</i> (98%) within 3 h of simulated solar light irradiation, exceeding that of TiO<sub>2</sub> nanospheres without annealing (amorphous) and TiO<sub>2</sub> nanospheres annealing at 350 and 550 °C (pure anatase). Furthermore, we design a photocatalytic antibacterial spray to protect the file paper. Our study reveals that the TiO<sub>2</sub> nanospheres with rutile/anatase heterojunctions are a potential candidate for maintaining the durability of paper in the process of archival protection.
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