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It has been rarely reported the morphological control of derivatives of metal‐organic frameworks (MOFs) in hydrothermal conditions for photocatalytic applications. We report here a family of highly efficient composite photocatalysts composed of terephthalic acid/terephthalate (TPA) ligand and TiO2 with various morphologies (e. g. nanoparticles, nanosheets, and nanorods). The composites are synthesized by a simple one‐step hydrothermal method in various solvents (i. e. H2O, HF, H2SO4, HCl, and HNO3) using Ti‐based MOF (MIL‐125(Ti)) as precursor. The formation mechanism of composite materials with different morphological features is discussed. Impressively, the composite of TiO2 nanoparticles/TPA synthesized using H2O as solvent under hydrothermal condition exhibits the highest photocatalytic H2 activity among the studied materials, with a photocatalytic H2 production rate of 6.38 mmol g−1 h−1, which is approximately 7.5‐fold higher than pure TiO2 (Degussa, P25) and prominent apparent quantum efficiency (AQE) of 65 % at 365 nm. Furthermore, the mechanism of boosted photocatalytic H2 production is discussed. [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] • [Mo 3 S 13 ]2− nanoclusters are highly dispersed into the micropores of TpPa-1-COF. • The size and micro-environment of micropores play a central role in anchoring MS-c. • The photocatalytic H 2 evolution rate of MS-c@TpPa-1 is increased by 4.7 times. • The coordinated Mo − N groups between MS-c and TpPa-1-COF result in enhanced stability. • The favorable electron–proton transfer to form H* occurs on the S instead of N sites. Non-noble-metal-based [Mo 3 S 13 ]2− nanoclusters (MS-c) as a co-catalyst face the problems of instability and inevitable aggregation, which limit its photocatalytic applications. Herein, β-ketoenamine-linked covalent organic framework (COF), namely TpPa-1-COF, was utilized to embed MS-c. The micropores of TpPa-1-COF could not only limit the growth of MS-c to achieve its high dispersion but also play a central role in anchoring MS-c. Moreover, the structural stability of MS-c is highly enhanced due to the confinement effect of TpPa-1-COF, and the visible-light-driven photocatalytic H 2 evolution rate of 528 μmol g−1h−1 for MS-c@TpPa-1 (0.3: 1), which is increased by 4.7 times as compared with that of TpPa-1-COF. The density functional theory (DFT) calculations indicate that the electrons transfer from TpPa-1 to MS-c occurs at the interface of MS-c@TpPa-1 in the ground state based on the charge density difference analysis. With the irradiation of visible light, the photoexcited electrons derived from the π-conjugated TpPa-1-COF backbone could be delivered to the embedding MS-c through the coordinated Mo − N groups, and the favorable electron–proton transfer to form H* and efficient desorption of H 2 occurs on the S sites instead of N sites in MS-c@TpPa-1, resulting in the enhanced photocatalytic H 2 evolution rate. Overall, this work provides a novel approach for embedding the unstable MS-c with low cost into the micropores of COF via coordination bonds to improve the structural stability and photocatalytic activity. [ABSTRACT FROM AUTHOR]

Ag3PO4 triangular prism was synthesized by a facile chemical precipitation approach by simply adjusting external ultrasonic condition. The as-synthesized Ag3PO4 triangular prism was characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectra, and ultraviolet-visible diffuse reflectance (UV-vis DRS) absorption spectra. The photocatalytic activity of Ag3PO4 triangular prism was evaluated by photodegradation of organic methylene blue (MB), rhodamine B (RhB), and phenol under visible light irradiation. Results showed that Ag3PO4 triangular prism exhibited higher photocatalytic activity than N-doped TiO2 and commercial TiO2 (P25) under visible light irradiation. [ABSTRACT FROM AUTHOR]

Ag 3 PO 4 /TiOF 2 composite photocatalysts were synthesized by a facile chemical precipitation approach using as-prepared TiOF 2 cubes as precursor. The as-synthesized Ag 3 PO 4 /TiOF 2 composites were characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), and UV–vis absorption spectra. The photocatalytic activity and stability of as-synthesized samples were evaluated by photo-degradation of organic methylene blue (MB) under visible light irradiation. Results showed that pure Ag 3 PO 4 exhibited poor photocatalytic stability. However, when Ag 3 PO 4 and TiOF 2 were compounded, the stability of composite photocatalysts was highly enhanced. Furthermore, the reason for enhanced photocatalytic stability of Ag 3 PO 4 /TiOF 2 composites was discussed. [ABSTRACT FROM AUTHOR]

Using density-functional theory (DFT) calculations within the generalized gradient corrected approximation, the models that nonmetallic impurities X (X = C, N, S, F) substituted for O or Ti sites in anatase TiO 2 were investigated. By calculating the formation energy of X-monodoped TiO 2 with X substituted for O, we suggested that X dopants existed as C 4− , N 3− , S 2− and F − ions, respectively. Meanwhile, the X dopants existed as C 4+ , N 3+ , and S 6+ for X-monodoped (X = C, N, S) TiO 2 with X substituted for Ti. The conclusion of the valence states of nonmetallic impurities X substituted for O or Ti sites in TiO 2 is also supported by the results of optimized cell parameters and the local structures. Furthermore, an effective nonmetallic passivated codoping approach to modify the band edges of TiO 2 is proposed. Based on the first-principle calculations, we suggested that nonmetallic passivated groups such as (S 2− + C 4+ ) and (C 4− + S 6+ ) could reduce the band gap largely and make less perturbation in conduction band minima (CBM), thus lead to an ideal visible-light absorption region without affecting the reducing power. This work provides some new results and is anticipated to give some inspiration and guidance for design visible-light-driven TiO 2 photocatalyst with high efficiency. [ABSTRACT FROM AUTHOR]

C-doped, Mo-doped, and (Mo, C)-codoped TiO2 photocatalysts were prepared by a sol-gel process. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange (MO) under simulated solar irradiation. Results indicated that both monodoped and codoped TiO2 exhibited better visible light absorption behavior and narrower energy gap than pure TiO2, and codoped TiO2 showed a slightly higher adsorption property in the dark because of higher Brunauer-Emmett-Teller-specific surface area. The photocatalytic activity of monodoped TiO2 was also enhanced, and the (0.04% Mo, C)-codoped sample had the best photocatalytic activity for degrading MO among all of the samples. The reason can be ascribed to the synergistic effect due to Mo and C doping. Furthermore, the transfer pathways of photoinduced carriers and photocatalytic reaction mechanism of (Mo, C)-codoped TiO2 was first investigated. [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]

As a visible-light photocatalyst, bismuth iodide oxide (BiOI) is widely applied in water photocatalytic pollution degradation. However, due to the inherent high recombination rate of electron−hole pairs, an efficient photocatalytic performance could realize rarely by bare BiOI, resulting in its limited practical application. In this study, a novel type-II BiOI−C 3 N 5 heterostructure was prepared by a feasible solvothermal method to inhibit the recombination of photoexcited electrons and holes. The photocatalytic activity of the heterostructure was evaluated by degradation of tetracycline (TC) and penicillin G sodium. The results showed that compared with bare C 3 N 5 and BiOI, the photodegradation efficiency of tetracycline and penicillin G sodium was remarkable improved after heterostructure formation and the BiOI−C 3 N 5 (10% wt) samples demonstrated a higher degradation efficiency. The improvement of photocatalytic degradation activities can be attributed to the formation of type-II heterostructures with a close contact. Under the synergistic effect and interface structure in BiOI−C 3 N 5 , the spatial separation and transfer of charge carriers were increased significantly, which is in favor of enhancing the photocatalytic oxidation capacity of BiOI. [Display omitted] • A new BiOI-C 3 N 5 heterostructure was successfully constructed to heighten the photocatalytic oxidation capacity of BiOI. • Synergistic effect and interfacial fusions in BiOI −C 3 N 5 were formed for accelerating the charge carriers transfer. • The BiOI−C 3 N 5 heterostructures exhibit remarkable tetracycline (TC) and sodium penicillin G degradation performances. [ABSTRACT FROM AUTHOR]