Solar‐driven reduction of dinitrogen (N2) to ammonia (NH3) is severely hampered by the kinetically complex and energetically challenging multielectron reaction. Oxygen vacancies (OVs) with abundant ...localized electrons on the surface of bismuth oxybromide‐based semiconductors are demonstrated to have the ability to capture and activate N2, providing an alternative pathway to overcome such limitations. However, bismuth oxybromide materials are susceptible to photocorrosion, and the surface OVs are easily oxidized and therefore lose their activities. For realistic photocatalytic N2 fixation, fabricating and enhancing the stability of sustainable OVs on semiconductors is indispensable. This study shows the first synthesis of self‐assembled 5 nm diameter Bi5O7Br nanotubes with strong nanotube structure, suitable absorption edge, and many exposed surface sites, which are favorable for furnishing sufficient visible light‐induced OVs to realize excellent and stable photoreduction of atmospheric N2 into NH3 in pure water. The NH3 generation rate is as high as 1.38 mmol h−1 g−1, accompanied by an apparent quantum efficiency over 2.3% at 420 nm. The results presented herein provide new insights into rational design and engineering for the creation of highly active catalysts with light‐switchable OVs toward efficient, stable, and sustainable visible light N2 fixation in mild conditions.
A facile wet chemical method for water‐assisted self‐assembly of 5 nm diameter Bi5O7Br nanotubes is reported. The obtained 5 nm Bi5O7Br‐NT is characterized with large surface area (>96 m2 g−1), suitable absorption edge, and sufficient surface oxygen vacancies of light switch. As a result, 5 nm Bi5O7Br‐NT delivers an excellent visible light driven photocatalytic N2 fixation performance with a NH3 generation rate of 1.38 mmol h−1 g−1 in pure water.
Abstract
Photoreduction of CO
2
to fuels offers a promising strategy for managing the global carbon balance using renewable solar energy. But the decisive process of oriented photogenerated electron ...delivery presents a considerable challenge. Here, we report the construction of intermolecular cascaded π-conjugation channels for powering CO
2
photoreduction by modifying both intramolecular and intermolecular conjugation of conjugated polymers (CPs). This coordination of dual conjugation is firstly proved by theoretical calculations and transient spectroscopies, showcasing alkynyl-removed CPs blocking the delocalization of electrons and in turn delivering the localized electrons through the intermolecular cascaded channels to active sites. Therefore, the optimized CPs (N-CP-D) exhibiting CO evolution activity of 2247 μmol g
−1
h
−1
and revealing a remarkable enhancement of 138-times compared to unmodified CPs (N-CP-A).
Donor–acceptor (D–A) conjugated polymers have proved to be desired candidates to couple with inorganic semiconductors for enhanced photocatalytic activity. Herein, the matched energy levels between ...polymer BFB and TiO2 make them form BFB‐TiO2 composites with moderate photocatalytic H2 evolution rate (HER). To further enhance the interfacial interaction, BFB was modified with a carboxylic acid end group, which reacted with surface OH of TiO2 to form an ester bond. As a result, the functionalized BFBA‐TiO2 composites exhibited superior photocatalytic activity. Especially, HER of 4 % BFBA‐TiO2 can reach up to 228.2 μmol h−1 under visible light irradiation (λ>420 nm), which is about 2.02 times higher than that of BFB‐TiO2. The enhanced photocatalytic activity originated from the formed ester bond between polymer and TiO2, and photogenerated electrons injection from lowest unoccupied molecular orbital (LUMO) of the exited polymer to conduction band of TiO2 were accelerated. Therefore, based on an intermolecular interaction mechanism, more suitable D–A conjugated polymers with anchoring groups could be designed to couple with other semiconductors for enhancing photocatalytic activity.
Hydrogen evolution: D–A Conjugated polymer BFB was coupled with TiO2 to form the composite BFB‐TiO2, and the photocatalytic H2 evolution ability was observed under visible irradiation. A carboxyl group was incorporated into the end of BFB, which enabled an ester bond formation between BFB and TiO2 to give BFBA‐TiO2 (see figure). This new composite exhibited an improved photocatalytic H2 evolution rate. This result provides a very effective strategy for constructing an efficient photocatalytic hydrogen evolution system.
To characterize the bacterial community in the primarily infected root canals.
A total of 13 samples were collected from the primarily infected root canals. 16 S rDNA sequencing was performed to ...define bacterial community. Taxonomic annotation, bacterial hierarchical structures, community richness and diversity, and inter-subject variability of the bacterial community in the root canal samples were analyzed. Gender, age, and duration of the toothache-specific bacterial community associated with the patient groups were analyzed.
A total of 359 Species were annotated and identified in the whole study cohort. The Alpha diversity analysis showed that the species diversity and detection rate of the 13 samples were high, which reflected the authenticity of sequencing results. The Beta diversity analysis was used to compare the degree of difference between different root canal samples. The 13 samples were divided into two groups according to the results, group A was samples I1-I12, and group B was samples I13. The bacterial species of group A samples were analyzed with the clinical characteristics of patients, and it was found that gender, and duration specific differences in bacterial species, and there was no significant difference in species types among different ages of patients.
There were a wide diversity and inter-subject variability in the bacterial community in the primary infected root canals. While Porphyromonas gingivalis was the most abundant species, Fusobacterium nucleatum was the most variable species in the bacterial community of the root canal. The bacterial community at different taxonomic levels varied from sample to sample, despite consistent disease diagnoses. There was gender, duration-specific differences in the bacterial species in the primary infected root canals.
This article introduces a cerebral thrombus protection device for the cerebral interventional treatment, also introduces the principle, design and manufacturing process of the device, and confirmes ...the effectiveness in vitro experiment.
Well-designed composite photocatalysts are of increasing concern due to their enhanced catalytic performance compared to a single component. Here, a photocatalyst composed of PbMoO4 (PMO) and ...poly-benzothiadiazole (BBT, a D-A-conjugated polymer) was successfully synthesized by BBT polymerization on the surface of the PMO. The resultant BBT-PMO with a heterojunction structure represented an enhanced ability to reduce highly toxic heavy metal Cr(VI) from water under visible light irradiation. The 16.7% BBT-PMO(N, nanoscale) showed the best performance. The corresponding kobs over the 16.7% BBT-PMO(N) was 26-fold (or 53-fold) of that over the pure BBT (or pristine PMO(N)), and this activity was maintained after four cycles. The reasons for its good performance are discussed in detail based on the experimental results. Moreover, the synthesis of the BBT in situ of the PMO also altered the morphology of the BBT component, increasing the specific surface area of the BBT-PMO(N) and endowing it with the ability to adsorb Cr(VI). Additionally, the photocatalyst was also environmentally friendly as such a wrapped structure could sustain the high stability of the PMO without dissociation. This work provides a good strategy for efficient photocatalytic Cr(VI) reduction by designing an organic–inorganic hybrid system with high redox capacity.
The search for appropriate materials with favorable staggered energy band arrangements is important and is a great challenge in order to fabricate Z-scheme photocatalysts with high activity in ...visible light. In this study, we demonstrated a facile and feasible strategy to construct highly active organic–inorganic Z-scheme hybrids (P-BMO) with linear pyrene-based conjugated polymer (P17-E) and Bi2MoO6, via an in-situ palladium-catalyzed cross-coupling reaction. The characterization results revealed C-O chemical bond formed at the heterointerface between P17-E and Bi2MoO6 after in-situ polycondensation and endowed the hybrids with observably improved photogenerated carries transfer capabilities. Visible, light-driven photocatalytic removal of ciprofloxacin and Cr(VI) were significantly enhanced after the incorporation of P17-E into Bi2MoO6, whether with the morphology of nanosheets, nanobelts, or microspheres. Moreover, these P-BMO hybrids were also found to exhibit excellent sustainable photocatalytic performance after four runs of photocatalytic evaluation tests, suggesting their high activity and stability. To better eliminate the redox ability enhancement of P-BMO, a reasonable Z-scheme electrons transferring mechanism between P17-E and Bi2MoO6 was proposed and proved by the determination of •O2– and •OH and Pt nanoparticles photodeposition experiments. This work might provide a viable source and insight into the design of Z-scheme photocatalysts with excellent redox ability for environmental remediation.
We here introduce octahedral silicon serving as a structural center for the design of hydrolytically stable bioactive complexes as demonstrated with the generation of silicon-based high affinity DNA ...binders. This proof-of-principle study suggests that octahedral silicon complexes are falsely neglected, promising structural templates for widespread applications in chemical biology and medicinal chemistry.
Covalent organic frameworks (COFs) are emerging as promising heterogeneous photocatalysts for organic transformations, owning to their fascinating optical properties, excellent recyclability, and ...customizable chemical structures. To maximize the photocatalytic activity of COFs, various strategies have been explored, including metal complexation, construction of donor‐acceptor structures, modification of functional groups, hybridization with inorganic semiconductors, and linkage conversion. Among these, linkage conversion has proved to be particularly effective, driving the production of numerous value‐added organic chemicals. In this concept article, we present a comprehensive overview of the latest advancements in linkage conversion and highlight the most enlightening examples that have adopted such a strategy to boost the photocatalytic capabilities of COFs for organic transformations. It is anticipated that this concept will assist researchers in designing novel COFs with multifunctional linkages, paving the way for their broader application in organic synthesis.
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•Z-scheme BBT–BMO was fabricated by facile in situ cross-coupling polycondensation.•BBT–BMO improves sulfathiazole photocatalytic degradation and Cr(VI) reduction.•The photogenerated ...e−/h+ separation efficiency of BBT–BMO is greatly enhanced.•The catalyst can work in a broad visible light region up to ∼700nm.
A novel conjugated microporous poly(benzothiadiazole)–Bi2MoO6 (BBT–BMO) Z-scheme heterojunction was fabricated in situ through a facile palladium-catalyzed Sonogashira–Hagihara cross-coupling polycondensation of 4,7-dibromobenzoc1,2,5thiadiazole and 1,3,5-triethynylbenzene on the surface of Bi2MoO6. Characterization results illuminated that BBT was stably coated on the surface of Bi2MoO6 nanosheets with the formation of CO bonds. This novel BBT–BMO composite exhibited superior photocatalytic performance in both sulfathiazole degradation and Cr(VI) reduction compared with pure BBT and Bi2MoO6 in visible light. In line with systematic characterizations results, a reasonable photocatalytic mechanism based on direct Z-scheme heterojunction was proposed and further verified via OH determination. This Z-scheme heterojunction endowed it with improved visible light absorption, larger surface area, and greater electron–hole separation and thus efficiently enhanced the photocatalytic performance. This work provides new insight into the utilization of conjugated microporous polymers in photocatalysis and paves a new way to construct Z-scheme heterojunctions with enhanced photocatalytic performance via metal-free polymers modification.
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