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One of the current key issues in the photocatalysis is to obtain the band alignment of coupled semiconductor experimentally, which is the most significant aspect for understanding the efficient photocatalytic activity precisely. In this article, a BiVO 4 /BiOI{001} heterojunction was detected by the transmission electron microscopy (TEM). The results of electrochemical impedance spectroscopy (EIS) reveal that a higher efficiency of charge immigration across the electrode/electrolyte interface for the BiVO 4 /BiOI{001}. In addition, the electron lifetime was investigated by the Bode phase plots, which are responsible for the observed photocatalytic behaviors. As a result, the photocatalytic activities for rhodamine B (RhB) degradation and iodine ion oxidation are remarkably increased compared to the individual BiVO 4 and BiOI{001}. In fact, a direct band alignment in the BiVO 4 /BiOI{001} does not give well a logical interpreting on its photocatalytic behavior. However, through the valence-band offset formula, we demonstrated the exact band alignment of corresponding components in the BiVO 4 /BiOI{001}. This band alignment was further confirmed by the PL spectra, which CM2 with photo-oxidation (Mn 2+ ) is red shift and CM2 with photo-reduction (Ag + ) is blue shift compared with CM2. [ABSTRACT FROM AUTHOR]

A p-n-type Bi 5 O 7 I-modified porous g-C 3 N 4 nano-heterojunction is synthesized via a simple preparation technique using the template method and annealing-hydrothermal co-deposition method. The results of SEM, EDS, elemental mapping, XRD, TEM, XPS and FT-IR imply that the Bi 5 O 7 I nanoparticles were successfully deposited on the surface of the g-C 3 N 4 nanosheets. The photocatalytic activity of the as-prepared p-n-type nano-heterojunction remarkably exhibits an enhancement of 30 times that of the unmodified samples. Furthermore, the photocatalytic degradation enhancement mechanism has been studied, which could be ascribed to the p-n-type nano-heterojunction and lamellar-porous structure of the g-C 3 N 4 . [ABSTRACT FROM AUTHOR]

In the present work, a series of layered BiOBr/g-C 3 N 4 heterojunction photocatalysts were prepared via a simple reflux process, and their photocatalytic performance was investigated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. It was found that BiOBr nanoplates were deposited on the external surface of g-C 3 N 4 nanosheets (CNNS) and the tightly contacted interface was formed between two components, giving rise to a 2D porous layered heterojunction structure with a high specific area. It was found that BiOBr nanoplates coupled with the proper amount of CNNS exhibited an excellent photocatalytic performance due to the combined effects of layered heterojunction, high specific surface area and porous structure, which lead to the high efficiency of light harvesting and charge separation. The active species of OH is the most crucial one while h + and O 2 − contributed to a lesser extent in RhB and BPA photocatalytic degradation. Based on the direct evidence of the formed OH, O 2 − and h + active species detected by active species capture experiment and ESR spectra, a Z-scheme photocatalytic mechanism was proposed for the charge separation. The present work may provide an insight for designing novel layered Z-scheme heterojunction photocatalysts with a high performance. [ABSTRACT FROM AUTHOR]