In-situ construction of 2D/2D β-Bi2O3/Bi5NO3O7 extra-low van der Waals heterojunctions with improved photocatalytic degradation activity

The construction of heterojunction nanomaterials offers a viable solution to enhance degradation capabilities. In this work, in-situ 2D/2D β-Bi 2 O 3 /Bi 5 NO 3 O 7 extra-low van der Waals (VDW) heterojunctions with oxygen vacancies are prepared by a simple solution combustion method. The successful preparation of extra-low VDW heterojunctions are verified by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Density Functional Theory (DFT), etc. The carrier flow direction is determined by DRS, Mott-Schottky, Kelvin probe and femtosecond transient absorption spectra (fs-TAS) characterization. The rate of photocatalytic degradation of Rhodamine B under visible light by the 5.6 β-Bi 2 O 3 /Bi 5 NO 3 O 7 (5.6 BBNO) heterojunction is 1.59 times that of Bi 5 NO 3 O 7 and 3.28 times that of β-Bi 2 O 3 . This is attributed to the extra-low van der Waals heterojunction, which not only enhances the separation efficiency of photogenerated carriers but also lowers the valence band maximum of Bi 5 NO 3 O 7 . Furthermore, capture agent experiments and EPR tests confirm that holes (h + ) play a key role in photocatalytic degradation.