Band alignment of BiOCl/ZnO core shell nanosheets by X-ray photoelectron spectroscopy measurements

To improve optoelectronic properties of bismuth oxyhalides, hybrid BiOX photocatalytic materials have draw a great attention, because of the separation of photogenerated electron-hole pairs. The band offset and band alignments are considered as the key parameters to elaborate carrier transport properties in heterojunction. In this paper, to determine the band alignment of BiOCl and ZnO heterostructure, BiOCl/ZnO core shell nanosheets with different thickness of shell layer were synthesized. The valence band offset (VBO or E-V) of BiOCl/ZnO heterostructure was determined using X-ray Photoelectron Spectroscopy measurements. The E-V value of 0.294 +/- 0.10eV was calculated by using the Zn 2p(3/2), Bi 4f(5/2) binding energies as references. Taking the band gaps of 3.37eV and 3.4eV for ZnO and BiOCl samples into consideration, respectively, we obtained the type-II band alignment of BiOCl/ZnO heterostructure with a conduction band offset (CBO or Ec) of 0.324 +/- 0.10eV.