In-situ topotactic synthesis and photocatalytic activity of plate-like BiOCl/2D networks Bi2S3 heterostructures

We herein demonstrate the uniform porous hierarchical plate-like BiOCl/2D networks Bi 2 S 3 heterostructures realized by a facile two-step hydrothermal technique. The synthesis involved an anion exchange process by reacting pre-synthesized BiOCl irregular octagonal nanoplates with Na 2 S 2 O 3 ·5H 2 O in an aqueous solution. The experiment results revealed that the 3D plate-like heterostructures were composed of internal BiOCl and outside networks interwoven by 1D Bi 2 S 3 nanorods . Interestingly, the heterostructures had almost the same thickness and the bigger length compared to the precursor BiOCl. We proposed the possible formation mechanism of the composites which involved selective ion-exchange reaction, the following Ostwald ripening process and epitaxial growth . And the crystal lattice matching between the a- or b-axis of tetragonal BiOCl (a   =   b   =   3.89   Å) and the a-axis of orthorhombic Bi 2 S 3 (a   =   3.981   Å) could be responsible for the in-situ topotactic transformation. Due to the formation of hetero-nanostructures, the unique spatial architecture features and the existence of oxygen vacancies, the BiOCl/Bi 2 S 3 composites exhibited significantly extended photo-responsive range and improved photocatalytic activity for reduction of Cr VI under visible-light irradiation. Moreover, the possible mechanism of photocatalysis process was investigated. Our work is expected to inspire further attempts for hierarchical and unconventional hetero-nanostructures with unique spatial architecture, which is very promising for photocatalysis and other applications.