Visible light-induced efficient contaminant removal by Bi₅O ₇I

A new visible light-driven photocatalyst, Bi₅O₇I, prepared by a hydrothermal method was studied. The as-prepared Bi ₅O₇I exhibited efficient photocatalytic activity in the decomposition of a widely used dye, tetraethylated rhodamine (RhB), in water and acetaldehyde (CH₃CHO) in air under visible light irradiation. Besides decoloring, the reduction of chemical oxygen demand concentration was also observed in the degradation of RhB, further demonstrating the photocatalytic performance of Bi₅O₇I. The results of density functional theory calculations indicated that the conduction band bottom of Bi₅O₇I is mainly composed of Bi 6p orbits, and the valence band top primarily consists of I 5p and O 2p orbits. The as-prepared Bi₅O₇I exhibited much higher photocatalytic activity than Bi₂O₃, which may be ascribed to the hybrid states of the valence bands as well as the internal electric fields between Bi ₅O₇ and I slabs. According to experimental results, a possible photocatalytic mechanism of Bi₅O₇I was proposed.