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As a visible-light response semiconductor materials, bismuth vanadate (BiVO4) is extensively applied in photodegradation organic dye field. In this study, we synthesized C3N5 nanosheets and coupled with decahedral BiVO4 to construct a Z-scheme C3N5/BiVO4 heterostructure with close interface contact. By introducing C3N5 into BiVO4, the built Z-scheme transfer pathway provides silky channel for charge carrier migration between different moieties and enables photoexcited electrons and holes accumulated on the surface of BiVO4 and C3N5. The accelerated separation of charge carriers ensures C3N5/BiVO4 heterostructures with a powerful oxidation capacity compared with pure BiVO4. Due to the synergistic effect in Z-scheme heterostructure, the C3N5/BiVO4 demonstrated an improved photodegradation ability of rhodamine B (RhB) and methylene blue (MB) that of bare BiVO4. [ABSTRACT FROM AUTHOR]

It remains challenging for the fabrication of metal-organic framework (MOF)/semiconductor heterojunction photocatalysts with close contact interfaces. In this work, a novel MOF/semiconductor heterojunction photocatalyst consisting of H 2 O 2 -modified TiO 2 nanotubes (H 2 O 2 -TNTs) and MIL-88B(Fe)-NH 2 (labeled as H-T/M) was firstly constructed based on the hydrogen-bonded combination between the O atoms from –OOH groups resulting from H 2 O 2 absorbed on the surface of TiO 2 nanotubes and the H atoms of the –NH 2 group in MOF. The significantly enhanced photocatalytic property of the H-T/M heterojunction for reducing Cr(VI) could be ascribed to the accelerated interfacial electron transfer dynamics by a channel of hydrogen bonds (N···H–O–O–Ti), which could be extracted from the femtosecond transient absorption spectroscopy (fs-TAS). Moreover, the built-in electric field and the differences in charge density based on density functional theory (DFT) calculations could provide the driving force for charge transfer. [Display omitted] • MOF/semiconductor heterojunction photocatalyst was firstly constructed. • Hydrogen-bonded combination between the –OOH groups and the –NH 2 group in MOF. • The significantly enhanced photocatalytic property of the H-T/M heterojunction for reducing Cr(VI). • The built-in electric field could provide the driving force for charge transfer. [ABSTRACT FROM AUTHOR]

[Display omitted] • An all-organic S-scheme heterojunction has been successfully developed. • The heterojunction contains a D-A type conjugated polymer and C 3 N 4 nanosheets. • The interfacial heterojunction was fabricated via a π-π conjugated interaction. • DFT calculations indicated the formed built-in electric field drove charge transfer. • The optimal P 2 CNNS exhibits photocatalytic H 2 evolution rate of 50.2 mmol·g−1 h−1. Designing an excellent photocatalyst with high space separation efficiency of photogenerated carriers to boost the rate of photocatalytic hydrogen (H 2) generation remains a challenge. In this work, the S-scheme heterojunction containing a donor–acceptor (D-A) type conjugated polymer of PyDTDO-3 and a two-dimensional (2D)-layered conjugated polymer of C 3 N 4 nanosheets with conjugated heptazine units (denoted as PCNNS) was prepared for photocatalytic H 2 production. It is found that the recombination rate of photogenerated electron-hole pairs is decreased by the S-scheme heterojunction structure through establishing an intimate π–π conjugated heterointerface between PyDTDO-3 and C 3 N 4 NS. To clarify the potential photocatalytic mechanism, diversified characterization techniques were employed and the density functional theory (DFT) calculations were conducted. As a result of the difference in the work function, a Fermi level gap is formed between PyDTDO-3 and C 3 N 4 , which eventually leads to the band edge bent upward/downward and the presence of the built-in electric field causing the spontaneous interfacial charge transfer from C 3 N 4 NS to PyDTDO-3 at the π–π conjugated interface. Owing to its unique structure and optical properties, the optimal P 2 CNNS heterojunction photocatalyst shows excellent photocatalytic H 2 generation performance, which reaches a maximum of 50.2 mmol g−1 h−1 under visible illumination. [ABSTRACT FROM AUTHOR]

A hydrothermal method was employed to synthesize the novel 2D/2D BiOCl/H+Ti 2 NbO 7 − heterojunction photocatalysts, showing the improved photocatalytic RhB degradation efficiency. • 2D/2D BiOCl/H+Ti 2 NbO 7 − heterojunction was synthesized by a hydrothermal route. • 2D/2D heterostructure facilitated the efficient charge separation and transfer. • BiOCl/H+Ti 2 NbO 7 − showed the high photoactivity due to heterojunction formation. • The h+ and •O 2 − played a crucial role in RhB photodegradation. To realize highly efficient removal of organic pollutant is a hot spot in environmental and energy science. Herein, we firstly prepared re-stacked H+Ti 2 NbO 7 − nanosheets (HTN) to fabricate the novel two-dimensional (2D)-2D BiOCl/H+Ti 2 NbO 7 − (BHT) heterojunctions by a hydrothermal method. The HTN were well combined with BiOCl nanoplates with an intimate interface to form a heterostructure. The rhodamine B (RhB) molecules were used as a target pollutant to evaluate the photocatalytic performance of samples under visible light. All BHT composites, with an optimal sample of BHT-4, showed the improved photocatalytic activity for degradating RhB compared with the single BiOCl and HTN. The enhanced activity was mainly attributed to the efficient charge separation and transfer, which was resulted from the formation of heterojunction between BiOCl and HTN. The produced active species can be detected by trapping experiments and ESR spectra. It indicated that hole (h+) and superoxide radical (O 2 −) played a crucial role in the photocatalytic RhB degradation, while hydroxyl radical (OH) contributed a little. A possible photodegradation mechanism was also discussed based on the corresponding experimental results. This work provides an insight for preparing 2D/2D heterojunctions with a high photocatalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • An entirely novel kind of GQDs-modified TpPa-1-COF photocatalyst was prepared. • GQDs were synchronously deposited onto the TpPa-1-COF by the in-situ method. • GQDs serve as a photosensitizer that enhances the optical absorption ability. • The 0.44% GQDs/TpPa-1-COF shows a better H 2 production than bare COF by 2.9 times. • DFT simulation indicates the highly efficient interfacial charge migration. The photocatalytic activity of covalent organic frameworks (COFs) to evolve hydrogen (H 2) triggered by visible light has been promising, but the separation and migration efficiency of photogenerated electron-hole pairs still have to be improved. In the study, we designed and synthesized a kind of graphene quantum dots (GQDs) modified β-ketoenamine-linked COF composite (GQDs/COF) by an in-situ method to improve its photocatalytic H 2 evolution for the first time. The resulting 0.44% GQDs/TpPa-1-COF shows a rate of H 2 production of 487 μmol g−1h−1 with the illumination of visible light, outperforming those of bare TpPa-1-COF by 2.9 times. It is found that the GQDs serve as a photosensitizer that effectively enhances the optical absorption ability. Moreover, GQDs serve as a means of collecting photoinduced electrons as for preventing the subsequent recombination of carriers excited by visible light. Furthermore, the Ohmic contact effect between the TpPa-1-COF and GQDs facilitates the highly efficient migration of photoinduced electrons, which has been demonstrated by the density functional theory (DFT) calculation results. Overall, this work provides a novel strategy to design COF-based composites and gives some insight into the role of GQDs on enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

A facile one-step calcination approach for the synthesis of ordered layered N-doped KTiNbO 5 /g-C 3 N 4 (NTNO/CN) heterojunction composites was developed. It was found that KTiNbO 5 layers were in-situ doped by nitrogen atoms to form N-KTiNbO 5 and two-layered g-C 3 N 4 nanosheets were formed within the interlayers of N-KTiNbO 5 due to the space-confined effects. The photocatalytic performance of the resulted composites was evaluated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. N-KTiNbO 5 coupled with a proper amount of g-C 3 N 4 exhibited an excellent photocatalytic performance due to the synthetic effects of N doping and layered heterojunction, leading to the high efficiency of light harvesting and charge separation. Especially, the in-situ intercalated two-layered g-C 3 N 4 nanosheets can significantly increase the contact area with N-KTiNbO 5 layers for efficient charge transfer across the interface, showing a much greater effect on the enhanced photocatalytic activity than those on the pure surface of N-KTiNbO 5 . It is expected that such a layered heterojunction can greatly speed up the separation and efficient transfer of photogenerated charge carriers. The active species of O 2 − played a leading role in the photocatalytic process while h + contributed to a lesser extent during the photocatalytic degradation of RhB over NTNO/CN-1, as determined by the active species capture experiment and ESR spectra. This work provides a new insight into the preparation of layered heterojunction hybrids with ordered alternative layered structure, and thus opens up the possibility of ‘design-and-build’ 2D layered heterojunctions for large-scale theoretical exploration and practical applications. [ABSTRACT FROM AUTHOR]