The relationship between secondary phase and photocatalytic activity in titanium-doped bismuth ferrite nanocrystals

Doping is an effective way to enhance photocatalytic activity. Herein, the authors have synthesised a series of BiFe1−x Ti x O3 (x = 0, 0.05, 0.10, 0.15, 0.20) nanocrystals through sol–gel methods. X-ray diffraction, Raman spectra, high-resolution transmission electron microscopy images and X-ray photoelectron spectroscopy characterisations indicate doping could facilitate the formation of Bi2Fe4O9 phase at low content, while inhibiting this formation at high content. Interestingly, the appearance of Bi2Fe4O9 improved the photocatalytic activity, which may be attributed to the spontaneous formation of heterostructure between Bi2Fe4O9 and BiFeO3 phases. The staggered energy bands between these two phases could effectively separate electrons and holes, resulting in enhanced photocatalytic performance.