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A wide bandgap conjugated polymer donor based on alkoxyl-fluorophenyl substituted benzodithiophene for high performance non-fullerene polymer solar cells
摘要： A highly enantioselective nucleophilic addition of ketones to imines catalyzed by chiral phase-transfer catalysts (N-quaternised cinchona alkaloid ammonium salts) has been developed, and the process affords the Mannich reaction products with tertiary stereocenters in good to high yields (up to 95%) with excellent enantioselectivities (up to 97% ee).
关键词： chiral phase transfer catalysts,asymmetric synthesis,β-amino ketones,cinchona alkaloid,Mannich reaction
更新于2025-09-11 14:15:04
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Triple-Shelled Co-VSex Hollow Nanocages as Superior Bifunctional Electrode Materials for Efficient Pt-Free Dye-Sensitized Solar Cells and Hydrogen Evolution Reactions
摘要： Complex nanostructures with distinct spatial architectures and more active sites hold broad prospects in new energy conversion fields. Herein, a facile strategy was carried out to construct triple-shelled Co-VSex nanocages, starting via an ion-exchange process about Co-based zeolitic imidazolate framework-67 (ZIF-67) nanopolyhedrons and VO3?, followed by the formation of triple-shelled Co-VSex hollow nanocages during the process of rising the solvothermal temperature under the assistance of SeO32?. Meanwhile, triple-shelled Co-VSx and yolk-double shell Co-VOx nanocages were fabricated as references by a similar process. Benefiting from the larger surface areas and more electrolyte adsorption sites, the triple-shelled Co-VSex nanocages exhibited excellent electrocatalytic performances when applied as the electrochemical catalysts for dye-sensitized solar cell (DSSC) and hydrogen evolution reaction (HER). More concretely, the DSSC based on Co-VSex counter electrode (CE) showed outstanding power conversion efficiency of 9.68% when Pt counterpart was 8.46%. Moreover, Co-VSex electrocatalyst exhibited prominent HER performance with a low onset overpotential of 40 mV and a small Tafel slope of 39.1 mV dec?1 in acid solution.
关键词： Dye-sensitized solar cells,Hydrogen evolution reactions,Pt-free catalysts,Triple-shelled nanocages,Co-VSex,Bifunctional electrocatalysts
更新于2025-09-11 14:15:04
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Well-dispersed zero-valent iron supported on Fe3O4/g-C3N4 composites via a facile approach with versatile photoredox catalysis
摘要： A well-dispersed Fe0/Fe3O4/g-C3N4 ternary hybrid composition was successfully synthesized through a calcination route followed by a hydrothermal treatment. It was significant to find that Fe0/Fe3O4/g-C3N4 possesses the optimal photocatalytic efficiency and excellent reusability toward Cr(VI) and RhB. The enhanced photocatalytic efficiency was attributable to the comprehensive factors including intimate contact of Fe0/Fe3O4 with g-C3N4, efficacious recombination inhibition of photoexcited carries, and synergistic interaction between each composition. Moreover, the photoredox catalytic mechanism of Fe0/Fe3O4/g-C3N4 was clearly proved by transient photocurrent responses, PL spectra properties, and exploring the formed active radicals that contribute to the improved photoredox activity. It is expected that our work could offer a notional guidance to design a promising photocatalytic compound for simultaneously degrading heavy metal ions and organic pollutant.
关键词： High-dispersed,Photostability,Synergistic,Fe0/Fe3O4/g-C3N4,Photocatalytic,Nanostructured catalysts
更新于2025-09-10 09:29:36
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Highly Efficient and Robust Photocatalytic Systems for CO <sub/>2</sub> Reduction Consisting of a Cu(I) Photosensitizer and Mn(I) Catalysts
摘要： The development of highly efficient, selective, and durable photocatalytic CO2 reduction systems that only use earth-abundant elements is key for both solving global warming and tackling the shortage of energy and carbon resources. Here, we successfully developed CO2 reduction photocatalysts using [Cu2(P2bph)2]2+ (CuPS) (P2bph = 4,7-diphenyl-2,9-di(diphenylphosphinotetramethylene)-1,10-phenanthroline) as a redox photosensitizer and fac-Mn(X2bpy)(CO)3Br (Mn(4X)) (X2bpy = 4,4′-X2-2,2′-bipyridine (X = ?H and ?OMe) or Mn(6mes) (6mes = 6,6′-(mesityl)2-2,2′-bipyridne)) as the catalyst. The most efficient photocatalysis was achieved by Mn(4OMe): The total quantum yield of CO2 reduction products was 57%, the turnover number based on the Mn catalyst was over 1300, and the selectivity of CO2 reduction was 95%. Electronic and steric effects of the substituents (X) in the Mn complexes largely affected both the photocatalytic efficiency and the product selectivity. For example, the highest selectivity of CO formation was achieved by using Mn(6mes) (selectivity SCO = 96.6%), whereas the photocatalytic system using Mn(4H) yielded HCOOH as the main product (SHCOOH = 74.6%) with CO and H2 as minor products (SCO = 23.7%, SH2 = 1.7%). In these photocatalytic reactions, CuPS played its role as an efficient and very durable redox photosensitizer, while remaining stable in the reaction solution even after a turnover number of 200 had been reached (the catalyst used had a turnover number of over 1000).
关键词： turnover number,Cu(I) photosensitizer,Mn(I) catalysts,photocatalytic CO2 reduction,earth-abundant elements,quantum yield,product selectivity
更新于2025-09-09 09:28:46
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Optical Spectroscopy Methods in the Estimation of the Thermal Stability of Bimetallic Pd–Rh/Al2O3 Three-Way Catalysts
摘要： A series of three-way catalysts containing palladium and rhodium were prepared by an incipient wetness impregnation of support with aqueous solution of [Pd(NH3)4](NO3)2 and Na3[Rh(NO2)6] compounds. Both pure and La-doped aluminum oxides were used as a support. The catalysts showed very close activity under stoichiometric and reductive conditions, but were different in terms of thermal stability being tested in a prompt thermal aging regime. UV–Vis and luminescence spectroscopies were found to be informative for diagnostics of rhodium and palladium concentration and state, thus giving the possibility to follow the changes taking place with active components (migration, agglomeration, bulk diffusion).
关键词： Metal migration,Prompt thermal aging,UV–Vis spectroscopy,Three-way catalysts,Luminescence spectroscopy
更新于2025-09-09 09:28:46
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TiO <sub/>2</sub> /zeolite Bifunctional (Photo)catalysts for a Selective Conversion of Methanol to Dimethoxymethane: On the Role of Br?nsted Acidity
摘要： In the present work, we report the first example of one-step selective methanol photooxidation to dimethoxymethane (DMM) at room temperature over TiO2/zeolite bifunctional catalysts. The effects of the porosity, basicity/acidity of the zeolites on the selectivity of the reaction are discussed. The role of TiO2 active sites and zeolitic Br?nsted acid sites on the DMM production is reported. As the photocatalytic reaction occurs at room temperature, the influence of the reaction temperature is also investigated to extrapolate the results to thermal catalysis. This study demonstrates a clear synergetic effect of the zeolites on the selectivity of the reaction. They can display an important impact on the selectivity of the photocatalytic reaction even at a low temperature (e.g. room temperature). Based on the obtained results, the reaction mechanism of methanol conversion to DMM is elucidated.
关键词： Br?nsted acidity,dimethoxymethane (DMM),selective conversion,methanol photooxidation,TiO2/zeolite bifunctional catalysts
更新于2025-09-09 09:28:46
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TiO2-catalyzed photodegradation of aromatic compounds: relevance of susceptibility to oxidation and electrophilic attack by hydroxyl radical
摘要： The application of nanostructured titanium dioxide (TiO2) as catalyst for the photodegradation of drugs and dyes is well established. We aimed to evaluate the importance of the reactivity of aromatic compounds submitted to photodegradation. Specifically, we were interested in the correlation between susceptibility to oxidation and/or to electrophilic attack and the efficiency of degradation. We demonstrated that hydroxyl radical (HO˙) is the most relevant species generated in the photodegradation process. Considering that HO˙ has both oxidizing and electrophilic features, the efficiency of degradation of selected aromatic compounds was performed. The choice was based on their susceptibility to oxidation and/or to electrophilic attack. Benzoic acid (C1), salicylic acid (C2), and protocatechuic acid (C3) were compared regarding their oxidability using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and were ranked as follows: C3 ? C2~C1. These compounds were efficiently photodegraded and no significant difference was observed among them. To assess the importance of susceptibility to electrophilic attack, anisole (C4), acetophenone (C5), and nitrobenzene (C6) were selected. Compared to C5 and C6, the higher susceptibility of C4 to electrophilic attack was demonstrated using hypochlorous acid, an electrophilic reagent. The photodegradation showed that C4 was also more susceptible to degradation compared to C5 and C6. In summary, we found that by acting as a powerful oxidant/electrophile agent, HO˙ was able to promote the degradation of aromatic moieties. Considering that the majority of drugs and dyes bear aromatic moieties, our findings explain the great success of photodegradation using metal oxides as catalysts.
关键词： Pharmaceutical drugs,Aromatic compounds,Titanium dioxide,Nanostructured catalysts,Electrophilic susceptibility,Photodegradation
更新于2025-09-04 15:30:14
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Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets || Layer-by-Layer Thin Films and Coatings Containing Metal Nanoparticles in Catalysis
摘要： The layer-by-layer (LbL) technique is one of the most promising ways of fabricating multilayer thin films and coatings with precisely controlled composition, thickness, and architecture on a nanometer scale. This chapter considers the multilayer thin films and coatings containing metal nanoparticles. The main attention was paid to LbL films containing metal nanoparticles assembled by convenient methods based on the different intermolecular interactions, such as hydrogen bonding, charge transfer interaction, molecular recognition, coordination interactions, as driving force for the multilayer buildup. Much attention has paid to the LbL films containing metal nanocomposites for multifunctional catalytic applications, in particular, photocatalysis, thermal catalysis, and electrocatalysis. The preparation protocol of LbL-assembled multilayer thin films containing metal nanoparticles (such as Au, Ag, Pd, Pt), metal oxides (Fe3O4), and sulfides (CdS) that are supported on the various surfaces of nanotubes of TiO2, Al2O3 membranes, graphene nanosheets, graphene oxide and further applications as catalysts with respect to photocatalytic, electrocatalytic performances is discussed. The systematization and analysis of literature data on synthesis, characterization, and application of multilayer thin films and coatings containing metal nanoparticles on the diverse supports may open new directions and perspectives in this unique and exciting subject.
关键词： semiconductors,metal nanoparticles,polyelectrolytes,layer-by-layer assembling,thin films and coatings,immobilization,catalysts
更新于2025-09-04 15:30:14
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From the Bottom-Up: Toward Area-Selective Atomic Layer Deposition with High Selectivity
摘要： Bottom-up nanofabrication by area-selective atomic layer deposition (ALD) is currently gaining momentum in semiconductor processing, because of the increasing need for eliminating the edge placement errors of top-down processing. Moreover, area-selective ALD offers new opportunities in many other areas such as the synthesis of catalysts with atomic-level control. This Perspective provides an overview of the current developments in the field of area-selective ALD, discusses the challenge of achieving a high selectivity, and provides a vision for how area-selective ALD processes can be improved. A general cause for the loss of selectivity during deposition is that the character of surfaces on which no deposition should take place changes when it is exposed to the ALD chemistry. A solution is to implement correction steps during ALD involving for example surface functionalization or selective etching. This leads to the development of advanced ALD cycles by combining conventional two-step ALD cycles with correction steps in multistep cycle and/or supercycle recipes.
关键词： surface functionalization,semiconductor processing,area-selective atomic layer deposition,catalysts synthesis,selectivity,bottom-up nanofabrication,selective etching,ALD
更新于2025-09-04 15:30:14
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Synthesis and Application of Substituted-1,16-dihydroxytetraphenylenes in Catalytic Asymmetric Allylboration of Ketones
摘要： The synthesis and application of a newly designed C2-symmetric chiral substituted-1,16-dihedroxytetraphenylenes (DHTP) is reported. Efficient syntheses of enantiopure substituted-DHTP were accomplished, and these enantiopure compounds were used as organocatalysts in asymmetric allylboration of ketones under very mild conditions. Accordingly, several tertiary alcohols were generated in moderate to good yields with up to 99% ee by using the catalyst (S)-2,15-Br2-DHTP. A gram-scale reaction was achieved in 99% yield with 96% ee.
关键词： 16-dihedroxytetraphenylenes,asymmetric allylboration,ketones,chiral catalysts,organocatalysis,substituted-1
更新于2025-09-04 15:30:14