Preparation and photocatalytic activity of Ag@AgCl modified anatase TiO₂ nanotubes

The combination of TiO₂ nanotubes and a surface plasmon resonance (SPR) photocatalyst used their large adsorption capacity and wide visible light response, respectively, and a synergistic effect to enhance photocatalytic activity under visible light irradiation. Anatase TiO₂ nanotubes were prepared by hydrothermal synthesis, a hydrogen peroxide treatment, and calcination at 400°C. AgCl nanoparticles were then loaded onto the TiO₂ nanotubes by a precipitation reaction, and some of the AgCl particles were reduced to Ag particles under halogen tungsten lamp irradiation. This gave a visible light SPR photocatalyst of Ag@AgCl/TiO₂ nanotubes that exhibited high photocatalytic activity, which was due to its large adsorption capacity, wide visible light response due to the SPR effect, fast separation of photogenerated electron-hole pairs, and strong oxidizing ability of Cl⁰ generated by combining Cl^- ions with photoexcited holes. Methylene blue dye was thoroughly decolorized within 1 h in the presence of this photocatalyst under visible light irradiation. In addition, the photocatalyst was stable after recycling the photocatalytic reaction five times.