Eu3+-doped Bi7O5F11 microplates with simultaneous luminescence and improved photocatalysis

Abstract

Doping of rare-earth ions in a host is one of the important strategies to modify the microstructure and electrical and optical properties. This work demonstrated the significant improvement of luminescence and photocatalytic performances of Bi7O5F11 via Eu3+ doping. Bi7O5F11 has a typical Sillén–Aurivillius structure, which shows an intrinsic luminescence band peaked at 527 nm with a decay time of 0.041 µs. The intrinsic emission quenches in Bi7O5F11:Eu3+, which shows characteristic transitions from 5D0,1,2,3 levels to 7FJ (J = 0–4) ground states. An experimental red-LED lamp was successfully fabricated by encapsulating Bi7O5F11:Eu3+ with a transparent resin. Bi7O5F11 has poor photocatalytic ability, which just can happen under UV light irradiation. The fast decay time (0.041 µs) of Bi7O5F11 causes an efficient recombination of the light-induced charges, resulting in a lower photocatalytic effect. Bi7O5F11:Eu3+ shows the improved photocatalytic abilities compared with pure Bi7O5F11. 4f levels of Eu3+ provide a longer decay time (1 ms) for the excited states of Bi7O5F11, which prevents the recombination of the light-induced charges. Importantly, Eu3+ doping moves the required wavelength in photocatalytic reactions from UV light (pure Bi7O5F11) to visible wavelength in Bi7O5F11:Eu3+. Bi7O5F11:Eu3+ could be further investigated to develop a multifunctional bismuth material such as dielectric, photoelectric, and photochemical abilities.