Solar energy‐driven conversion of CO2 into fuels with H2O as a sacrificial agent is a challenging research field in photosynthesis. Herein, a series of crystalline porphyrin‐tetrathiafulvalene ...covalent organic frameworks (COFs) are synthesized and used as photocatalysts for reducing CO2 with H2O, in the absence of additional photosensitizer, sacrificial agents, and noble metal co‐catalysts. The effective photogenerated electrons transfer from tetrathiafulvalene to porphyrin by covalent bonding, resulting in the separated electrons and holes, respectively, for CO2 reduction and H2O oxidation. By adjusting the band structures of TTCOFs, TTCOF‐Zn achieved the highest photocatalytic CO production of 12.33 μmol with circa 100 % selectivity, along with H2O oxidation to O2. Furthermore, DFT calculations combined with a crystal structure model confirmed the structure–function relationship. Our work provides a new sight for designing more efficient artificial crystalline photocatalysts.
COF catalysts: A series of crystalline covalent organic frameworks (COFs) was designed and applied for CO2 photoreduction coupled with H2O photooxidation, in the absence of photosensitizers and sacrificial agents. This approach gives a more straightforward and clear understanding of the structure–function relationship of artificial photosynthesis.
The outstanding visible light response of carbon nitride has aroused intense expectations regarding its photocatalysis, but it is impeded by the inevitable defects. Here, we report on a facile ...melamine-based defect-remedying strategy and resultant carbon nitride high-performance photocatalysts (R-C3N4). Melamine with amino groups and a triazine structure was selected as a “little patch” to passivate and remedy various defects inside carbon nitride. Such a remedying effect has been comprehensively proven by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analyses, and the ninhydrin test. In addition, their effects on photocatalysis were also individually confirmed by chemical methods, including cyano reduction reactions and deamination reactions. Furthermore, melamine remediation can result in g-C3N4/mpg-C3N4 junctions, which also favors electron transfer and charge separation during the photocatalytic reaction. In order to explore its broader applications, R-C3N4 was used as a photocatalyst for the photooxidation reaction of 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (1,4-DHP) and simultaneous H2 evolution. The conversion rates of 1,4-DHP and H2 production catalyzed by R-C3N4 were enhanced 2 and 6.5 times, respectively. This rational design is beneficial for the conversion of 1,4-DHP during the preparation of bioactive compounds and clean hydrogen production at the same time.
Abstract C 60 –bodipy triads and tetrads based on the energy‐funneling effect that show broadband absorption in the visible region have been prepared as novel triplet photosensitizers. The new ...photosensitizers contain two or three different light‐harvesting antennae associated with different absorption wavelengths, resulting in a broad absorption band (450–650 nm). The panchromatic excitation energy harvested by the bodipy moieties is funneled into a spin converter (C 60 ), thus ensuring intersystem crossing and population of the triplet state. Nanosecond time‐resolved transient absorption and spin density analysis indicated that the T 1 state is localized on either C 60 or the antennae, depending on the T 1 energy levels of the two entities. The antenna‐localized T 1 state shows a longer lifetime ( τ T =132.9 μs) than the C 60 ‐localized T 1 state (ca. 27.4 μs). We found that the C 60 triads and tetrads can be used as dual functional photocatalysts, that is, singlet oxygen ( 1 O 2 ) and superoxide radical anion (O 2 . − ) photosensitizers. In the photooxidation of naphthol to juglone, the 1 O 2 photosensitizing ability of the C 60 triad is a factor of 8.9 greater than the conventional triplet photosensitizers tetraphenylporphyrin and methylene blue. The C 60 dyads and triads were also used as photocatalysts for O 2 . − ‐mediated aerobic oxidation of aromatic boronic acids to produce phenols. The reaction times were greatly reduced compared with when Ru(bpy) 3 Cl 2 was used as photocatalyst. Our study of triplet photosensitizers has shown that broadband absorption in the visible spectral region and long‐lived triplet excited states can be useful for the design of new heavy‐atom‐free organic triplet photosensitizers and for the application of these triplet photosensitizers in photo‐organocatalysis.
Es wird gezeigt, dass Kovalenz die Ladungstrennung nach Photooxidation des Metallzentrums in einem Metall‐Ligand‐Ladungstransferzustand eines Eisensensibilisators ausgleicht. Die Fähigkeit der ...Liganden zur σ‐Bindung kompensiert den Verlust einer 3d‐Elementarladung am Eisenzentrum, sodass die ursprüngliche Ladungsdichte und lokale Edelgaskonfiguration am Metall erhalten bleibt. Diese Erkenntnisse werden durch elementspezifische und orbitalselektive zeitaufgelöste Röntgenabsorptionsspektroskopie an der Eisen‐L‐Kante ermöglicht. Die Population von Valenzorbitalen um das Metallzentrum wird so direkt zugänglich. Mit Hilfe von Dichtefunktionaltheorie stellen wir fest, dass das Bild einer lokalisierten Ladungstrennung inadäquat ist. Die ungepaarte Spindichte bietet jedoch eine geeignete Beschreibung des mit dem Elektronentransferprozess assoziierten Elektron‐Loch‐Paares.
Singlet oxygen is generated by the BODIPY photosensitizer, whose X‐ray structure is shown in the central part of the picture. The structures in the left and right corners of the doors are those of ...bis(benzothienylo)1,4thiaborins—basic building blocks of BODIPY. The sensitization process requires white light, which is symbolized by a light bulb. Triplet oxygen enters through the red door, where it is excited to the singlet state, and leaves through the blue door. More information can be found in the Research Article by P. H. Marek‐Urban, K. Durka, and co‐workers (DOI: 10.1002/chem.202300680). Artwork by P.H.M.‐U.
The tunability of the DPIC mechanism. A yellow‐emitting coumarin is connected to a “conversion meter” indicating the efficiency of conversion. The needle points at the different groups that have been ...attached to the pyrrole moiety. These groups are sorted from left to right according to the conversion yield, with a corresponding background ranging from dark to illustrate photo‐bleaching to blue to illustrate the photo‐conversion. More information can be found in the Research Article by M. Collot and co‐workers. (DOI: 10.1002/chem.202203933).
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•A cost-effective heterojunction photocatalyst was fabricated by solvothermal treatment.•The photo-degradation CH3CHO performance was enhanced greatly.•0.5Bi2O2CO3@PCN presented the ...best photoactivity among the as-prepared photocatalysts.•Bi2O2(OH)(NO3) was fully converted to Bi2O2CO3 by ion exchange reaction with PCN.•BIOC@PCN formation and its photocatalytic mechanism were proposed.
Constructing heterojunction between two semiconductors is a cost-effective pathway to fabricate efficient photocatalysts for environmental remediation and energy-related applications, which is with profound significance and high desirability to contemporary era. In this work, we demonstrate an extremely facile approach to couple bismuth subcarbonate with polymeric carbon nitride (denoted as BIOC@PCN) by ion exchange between home-made rose-like Bi2O2(OH)(NO3) (denoted as BION) and PCN bulks at 433 K solvothermal condition. PCN bulks play multi-roles in this ingenious one-pot method. Firstly, PCN bulks guarantee the negatively charged surface to anchor plentiful bismuth precursor salts. More importantly, solvothermal treatment affords a weak basic and sufficient CO32− ions environment to promote the following ion exchange reaction. The evolution of morphology, components and structure from rose-like BION to BIOC@PCN were symmetrically characterized by means of SEM, HR-TEM, XRD, FTIR, TG, UV–vis, BET-BJH and XPS. The as-prepared nanohybrid photocatalyst (0.5BIOC@PCN) presents optimal photocatalytic performance for gaseous acetaldehyde removal, which is showing 10, 6.5 and 2 times higher than that of the PCN-Bulk, BION and mechanical mixed BIOC/PCN counterparts, respectively. Transient photocurrent response and EPR results further verify the validity of the established heterojunction of BIOC@PCN in facilitating the separation of charge carriers. The performance improvement gains from the efficient separation of charge carriers in BIOC@PCN heterojunction, manifested by PL spectra, transient photocurrent response and EPR results. In this study, a facile and cost-effective approach to build PCN-based nanohybrid photocatalysts for gaseous acetaldehyde efficient removal was established.
In this study, sludges generated from Ti-based flocculation of dye wastewater were used to retrieve photoactive titania (S–TiO2). It was heterojunctioned with graphitic carbon nitride (g-CN) to ...augment photoactivity under UV/visible light irradiance. Later the as-prepared samples were utilized to remove nitrogen oxides (NOx) in the atmospheric condition through photocatalysis. Heterojunction between S–TiO2 and g-CN was prepared through facile calcination (@550 °C) of S–TiO2 and melamine mix. Advanced sample characterization was carried out and documented extensively. Successful heterojunction was confirmed from the assessment of morphological and optical attributes of the samples. Finally, the prepared samples’ level of photoactivity was assessed through photooxidation of NOx under both UV and visible light irradiance. Enhanced photoactivity was observed in the prepared samples irrespective of the light types. After 1 h of UV/visible light-based photooxidation, the best sample STC4 was found to remove 15.18% and 9.16% of atmospheric NO, respectively. In STC4, the mixing ratio of S–TiO2, to melamine was maintained as 1:3. Moreover, the optical bandgap of STC4 was found as 2.65 eV, where for S–TiO2, it was 2.83 eV. Hence, the restrained rate of photogenerated charge recombination and tailored energy bandgap of the as-prepared samples were the primary factors for enhancing photoactivity.
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•Successful heterojunction of sludge generated TiO2 and g-CN.•Effective NOx removal has been observed under UV/visible light.•Heterojunction caused optical bandgap narrowing and reduced charge recombination.•NOx removal mechanism was explained using advanced characterizations.
Abundant and affordable methane is not only a high‐quality fossil fuel, it is also a raw material for the synthesis of value‐added chemicals. Solar‐energy‐driven conversion of methane offers a ...promising approach to directly transform methane to valuable energy sources under mild conditions, but remains a great challenge at present. In this Review, recent advances in the photocatalytic conversion of methane are systematically summarized. Insights into the construction of effective semiconductor‐based photocatalysts from the perspective of light‐absorption units and active centers are highlighted and discussed in detail. The performance of various photocatalysts in the conversion of methane is presented, with the photooxidation classified according to the oxidant systems. Lastly, challenges and future perspectives in the photocatalytic oxidation of methane are described.
The conversion of methane driven by solar energy offers a promising approach to directly transform methane into valuable energy sources under mild conditions, but remains a great challenge. This Review highlights recent advances in the photocatalytic conversion of methane and gives insights into the design of effective semiconductor‐based photocatalysts and classifies the photooxidations according to the oxidants in the reaction system.
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![Front Cover: Bis[1]benzothi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0947-6539_1521-3765/small "Front Cover: Bis[1]benzothieno[1,4]thiaborins as a Platform for BODIPY Singlet Oxygen Photosensitizers (Chem. Eur. J. 36/2023)")
