Visible light-induced photocatalytic oxidation of phenol and aqueous ammonia in flowerlike bi2fe4o9 suspensions

Photocatalytic active flowerlike Bi₂Fe₄O₉ was synthesized by a hydrothermal method. Scanning (SEM) and transmission electron microscopy (TEM) images revealed that the photocatalysts are composed of wellcrystallized nanoplates along the (100) plane. The as-prepared nano-Bi₂Fe₄O₉ exhibited excellent photocatalytic oxidation of phenol and aqueous ammonia under visible light irradiation. Much enhanced photocatalytic performance for phenol oxidation was observed with the assistance of a small amount of H₂O₂. For guiding the further improvement of its photocatalytic activity, the relationship between the electronic structure and the photocatalytic performance of Bi₂Fe₄O₉ is revealed by ab initio calculations for the first time. The calculation results indicate Bi ₂Fe₄O₉ is a multiband semiconductor, and the principle for an improved photocatalytic performance is to increase the efficiency of electron-hole separation considering the middle energy band that may act as electron-hole recombination centers.