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 well-crystallized 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 Bi2Fe4O9 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.