Construction of one-dimensional pn heterojunction TiO₂/CuO composite with hierarchical structure and its dual efficient inactivation of Escherichia coli

Photocatalytic antimicrobial is a promising advanced oxidation antibacterial technology that can utilize solar energy to achieve antibacterial function. However, due to the influence of diurnal variation, photocatalytic antimicrobials cannot maintain a continuous antibacterial effect in practical applications. Herein, a TiO₂ fiber with CuO particle (TiO₂/CuO) pn-type heterojunction with dual inactivation of Escherichia coli has been designed and prepared for water treatment. The formation of pn heterojunction and its high efficiency of charge separation and transfer were confirmed through HRTEM, FESEM, UV–Vis and photoelectrochemical tests, while the charge separation process of the heterojunction under visible-light irradiation was systematically investigated. The results showed that the antimicrobial rate of TiO₂/CuO composites was 64.7% at 10 min under dark conditions. In contrast, under light exposure, the antibacterial rate could reach 96.2% for 10 min and 100% for 20 min. This research holds promise for advancing the construction of pn heterojunctions and provides a novel insight into reducing the dependence of photocatalytic antimicrobials on light.