Robust photocatalytic activity of two-dimensional h-BN/Bi₂O₃ heterostructure quantum sheets

Herein, defect intrinsic hexagonal boron nitride (h-BN) quantum sheets (QS) and bismuth oxide (Bi₂O₃) QS were prepared from bulk materials by ball milling and solvent stripping, respectively. The h-BN/Bi₂O₃ heterostructure was fabricated via a facile self-assembly method. The structure and performance of samples were systematically characterized. As expected, the layered h-BN QS is tightly coated on the surface of Bi₂O₃ QS in a face-to-face stacking structure and interconnected by strong interface interactions. The introduction of h-BN QS can significantly enhance the separation efficiency of the photogenerated carriers of h-BN/Bi₂O₃. The experimental results show that the photocatalytic activity of h-BN/Bi₂O₃ is markedly improved. The first-order reaction rate constant of the 3wt%-BN/Bi₂O₃ sample is 3.2 × 10^-2 min^-1, about 4.5 times that of Bi₂O₃ QS. By means of the active species capture test, it is found that the main oxidation species are holes (h⁺), followed by hydroxyl radicals (˙OH). Based on the surface charge transfer characteristics, the photogenerated carrier transfer and separation efficiency can be improved by coupling h-BN and a Bi₂O₃ semiconductor to the Schottky heterojunction, and the strong interaction between heterogeneous interfaces also enhances the surface catalytic reaction efficiency, which improves dramatically the photocatalytic performance.