Surface Modification of Bi2O3 with Fe(III) Clusters toward Efficient Photocatalysis in a Broader Visible Light Region: Implications of the Interfacial Charge Transfer

The surface modification of Bi2O3 with Fe(III) ions has been achieved through an impregnation technique. The Fe(III)-modified Bi2O3 exhibits a much higher photocatalytic activity for the degradation of Orange II than bare Bi2O3 in a broader visible light region. Based on various characterization results and ESR measurements, it was revealed that in the visible light beyond the bandgap energy of Bi2O3 the surface Fe(III) modification induces a direct interfacial charge transfer (IFCT) from the valence band of Bi2O3 to the surface Fe(III) clusters, where Fe(III) can serve as an oxygen reduction site. This IFCT process has been clearly demonstrated to play a critical role in the higher photocatalytic performance of the Fe(III)-modified Bi2O3 by offering a new channel for the efficient generation of the hole in the valence band of Bi2O3 substrate. The photocatalytic mechanisms of the Fe(III)/Bi2O3 in different visible light regions are also discussed in detail.