Highly efficient photocatalytic activities, band alignment of BiVO4/BiOCl {001} prepared by in situ chemical transformation

• BiVO4/BiOCl has been successfully synthesized by in situ chemical transformation.
• We obtain experimentally band alignment of BiVO4/BiOCl through valence-band offset.
• Valence band offset shows that VB of BiOCl lies 0.58 eV above that of BiVO4.
• Prolonged electrons lifetime in BiVO4/BiOCl is in favor of high photocatalytic properties.

The proper band alignment of coupled semiconductor plays a key role on enhancing photocatalytic activity due to the valence and conduction difference in the interface to drive the photogenerated charge carrier separation. However, little is known about the exact band alignment of coupled semiconductors due to that most band alignments were schematic by valence of monocomponent, but not consider the interface effect of coupled semiconductors. Herein the novel synthesis strategy via in situ chemical transformation was successfully utilized to prepare BiVO4/BiOCl {001} heterojunctions. The results of transmission electron microscopy (TEM) show that BiVO4/BiOCl photocatalyst was made of BiOCl sheets and BiVO4 nanoparticles. The exact band alignment was experimentally demonstrated in BiVO4/BiOCl through X-ray photoelectron spectroscopy (XPS). The results show that the valence band difference is 0.58 eV which is a driving force valence of band holes from BiVO4 to BiOCl by the valence band offset. While the reductive electrons were driven by conduction band difference (1.27 eV) along the opposite direction compared to the oxidative holes. The large driving force for the charge transport across the interface explains the high photocatalytic activity achieved by the BiVO4/BiOCl.

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