Band alignment and enhanced photocatalytic activation for α-Bi2O3/BiOCl (0 0 1) core–shell heterojunction

In order to develop low-cost photocatalyst, commercial Bi 2 O 3 was utilized as raw material to prepare α-Bi 2 O 3 /BiOCl core-shell heterojunction via a facile in situ chemical transformation method. To clarify experimentally the band alignment relationships between the α-Bi 2 O 3 and BiOCl (0   0   1), the α-Bi 2 O 3 /BiOCl (0   0   1) core–shell heterojunction band offsets were analyzed by X-ray photoelectron spectroscopy (XPS). Here based on energy gaps, valence band values of α-Bi 2 O 3 and BiOCl (0   0   1), core levels difference of Bi 4f in α-Bi 2 O 3 /BiOCl (0   0   1) heterojunction , we demonstrate that band alignment of ∼0.28   eV exists between α-Bi 2 O 3 and BiOCl with α-Bi 2 O 3 possessing the higher valence band potential or electron affinity which is a driving force of valence band holes from α-Bi 2 O 3 to BiOCl (0   0   1). While, the electrons in conduction band were driven to migrate through conduction band potential difference (0.49   eV) from BiOCl (0   0   1) to α-Bi 2 O 3 .