Latest ArticlesThe self-assembled behavior of an unsymmetric molecule (BCDTDA) with one imidazole group as center and benzoic acid group as functional group is studied, and the regulatory behaviors of coronene (COR) and three bipyridine derivatives (named BP, PEBP-C4 and PEBP-C8) on BCDTDA self-assembly structures are also investigated. Based on highly oriented pyrolytic graphite (HOPG) substrate, scanning tunneling microscopy (STM) is used to observe the variation of assembled behaviors at the solid-liquid interface. Because of the concentration effect, BCDTDA molecules can assemble into grids and Kagomés structures in the form of NH···O hydrogen bonded dimers. BCDTDA molecules still maintain dimeric structures in the regulation of COR and BP molecules to BCDTDA self-assembly. However, PEBP-C4 and PEBP-C8 destroy the structure of the dimers, and form a variety of co-assembled structures with BCDTDA. Different guest molecules coordinate the host molecules differently, which makes the experiment more meaningful. Combined with density functional theory (DFT) calculation, the discovery of molecular interactions provides a promising strategy for the construction of functional nanostructures and devices.
Herein, we discovered that the surface-confined condensation of boronic acid can happen spontaneously at room temperature, by comparing the kinetics of condensation of boronic acids with and without the negative sample bias, we found that the negative sample bias indeed accelerates the self-condensation reaction of boronic acid. Combining with in-situ STM images and ultraviolet photoemission spectrum (UPS) analysis, a reversible adsorption mechanism model was proposed and reasonably explains the reversible electric-field-induced phase transformation.
Luminescent polymers have garnered considerable research attention for their excellent properties and wide range of applications in multi-responsive materials, bioimaging, and photoelectric devices. Thereout, various modulations of polymer structure are often the main approach to obtaining materials with different luminescent colors and functions. However, polymers with biodegradability, tunable color, and efficient emission simultaneously remain a challenge. Herein, we report a feasible strategy to achieve degradable and highly emissive polymers by exquisite combination and interplay of aggregation-induced emission (AIE) unit and environmental-friendly epoxide/CO2 copolymerization. A series of polycarbonates P-TEPxCNy (x = 0, 1, 2, 4, 30, 120; y = 0, 1) were prepared, with emission color changed from blue to yellow by controlling the proportion of two designed AIE-active monomers. Among them, Using P-TCN as emitting layer, high performance white light-emitting diode (WLED) device with an external quantum efficiency (EQE) of 26.09% and CIE coordinates of (0.32, 0.32) was achieved. In addition, the designed polymers can be used as selective sensors for nitroaromatic compounds in their nanoaggregate states.
Carbon dioxide-based polyols with ultra-low molecular weight (ULMW, Mn < 1000 g/mol) are emergent polyurethane precursors with economic and environmental benefits. However, the lack of effective proton-tolerant catalytic systems limits the development of this field. In this work, the polymeric aluminum porphyrin catalyst (PAPC) system was applied to the copolymerization of CO2 and propylene oxide, where sebacic acid, bisphenol A, poly(ethylene glycol), and water were used as chain transfer agents to achieve the controlled synthesis of CO2-polyols. The molecular weight of the resulting CO2-polyols could be facilely regulated in the range of 400–930 g/mol at low catalyst loadings, fully demonstrating its catalytic advantages of high activity, high product selectivity, and excellent proton tolerance of PAPC. Meanwhile, the catalytic efficiency of PAPC could reach up to 2.1–5.2 kg/g under organic CTA conditions, even reaching 1.9 kg/g using water as the CTA. The cPC content could be controlled within 1.0 wt% under the optimized conditions, indicating the excellent controllability of the PAPC system. ULMW CO2-polyols combines the advantages of low viscosity (~3000 mPa s at 25 ℃), low glass transition temperature (~−73 ℃), and high carbonate unit content (~40%), which is important for the development of high-performance polyurethanes.
Single-atom nanozymes (SANs) have attracted extensive attention due to their characteristics of both single-atom catalysts (SACs) and enzymes. Using spin-polarized density functional theory (DFT) calculations combined with the hybrid solvation model, this work designed a series of carbon-supported Group Ⅷ transition metals TMS4-C SANs, similar to the TMS4 active center of formate dehydrogenase (FADH), aiming to develop highly efficient SANs for CO2 electroreduction. DFT calculations show that compared with TMN4-C, TMS4-C have FADH-like feature, which can selectively reduce CO2 to formic acid. Particularly, CoS4-C is the most promising SAN for CO2 reduction, with a low limiting potential of -0.07 V, which exceeds most reported catalysts. Two descriptors of TMX4-C (X = N, S) based on intrinsic and electronic structure properties were proposed to shed light on the origin activity of candidates. The findings presented here will provide new insights into the design of novel enzyme-like catalysts for electrochemical CO2 reduction.
The stability issue is one of the key factors hindering the commercial application of organic solar cells. All-polymer organic solar cell is one of the effective ways to solve the stability problem. In this work, we designed and synthesized two polymer donor materials PBDT and PDTBDT with different conjugation ranges, and demonstrated for the first time that extending the conjugation range of donor materials in all polymer solar cells can significantly improve device efficiency and stability. The experimental results of materials and devices show that PDTBDT with a larger conjugation range has stronger crystallinity and a more planar structure, which endows the active layer in its corresponding device with higher exciton dissociation probability, lower carrier recombination probability, more balanced charge transport properties and more favorable film morphology. As a result, the PDTBDT: PYF-T-o devices display an outstanding PCE of 13.38%, which is much higher than PBDT with smaller conjugation range based devices. Moreover, the PDTBDT: PYF-T-o device retains 0.86 of the initial PCE after over 500 h in the air atmosphere, exhibiting significantly improved stability. The improved stability is attributed to the enhanced moisture and air tolerance of active layer film thanks to the strong crystallinity of the donor material. These results demonstrate that the conjugation expansion strategy is one of the effective ways to obtain efficient and stable all-polymer organic solar cells.
Membrane filtration is one of the effective approaches to harvest microalgae for industrial biofuel production. However, during the filtration process, microalgae cells and extracellular organic matter (EOM) will deposit on the membrane surface leading to reversible membrane fouling that can be removed by physical methods. When hydrophobic EOM is adsorbed on the membrane surface or inside pores, it will build up a gel layer, causing irreversible membrane fouling. Irreversible fouling can only be removed using chemical methods that will decrease membrane lifespan and increase operational costs. Here, we introduce a versatile superhydrophilic membrane with photo-Fenton self-cleaning property, which can prevent the reversible fouling and remove the irreversible fouling. Tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) were co-deposited on the polyvinylidene fluoride (PVDF) membrane via Schiff base and Michael addition reactions, and β-FeOOH nanorods were inlaid on the membrane surface by in situ mineralization. The water contact angle of the modified membrane is reduced from 120° to 0° Under 60 min visible light, the hydroxyl radical (·OH) generated by the photo-Fenton reaction degraded the irreversible fouling that blocked membrane pores. The irreversible fouling rates of modified membrane was reduced from 39.57% to 3.26%, compared with the original membrane. Microalgae harvesting results illustrated that the membrane has a high flux recovery rate (FRR) of 98.2%, showed excellent passive antifouling and active antifouling performance. We believe this work will spark a novel platform for optimizing energy-efficient microalgae harvesting separation membrane modules. In addition, this method of anti-fouling filtration for microorganisms can be extended to the industrial production of various bioenergy sources and will have very promising practical applications.
Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) is of great significance in petrochemical industry, but still remains as a daunting challenge by reason of their very similar molecular sizes/shapes and physical properties. Herein, we reported a new perchlorate-based hybrid ultramicroporous material ZJU-194 that features the unique flexible-robust network decorated with rich bare oxygen atoms. By integrating the refined pore space as well as specific binding sites, the activated ZJU-194 (ZJU-194a) enables a selective two-step gate-opening adsorption toward C2H2, but blocks off the further uptake of CO2. It thus exhibits a very high C2H2/CO2 selectivity (22.4) at ambient conditions, which is superior to most reported MOF materials. Its complete separation for 50/50 C2H2/CO2 mixtures is further evidenced by the dynamic breakthrough experiments.
Chiral high-nuclearity lanthanide (4f) clusters have shown fantastic properties in various fields. However, their synthesis is still of great challenge. Herein, we report two pairs of enantiomers of high-nuclearity Dy-oxo clusters synthesized through in situ strategy. They are [Dy18(R/SHftp)4 (R/SH2btp)4(μ2-OH)8(μ3-OH)20(μ6-O)(NO3)4(μ-H2O)8]·[solvents] (1R and 1S) and [Dy9(R/SHftp)2 (R/SH2btp)2(OAc)6(μ3-OH)10(H2O)6](OAc)·[solvents] (2R and 2S), where R/SHftp2− and R/SH2btp3− represent in situ formed 2-formyl-6-[N-(threonine)iminomethyl]-4-methylphenol and 2,6-bis[N-(threonine)iminomethyl]-4-methylphenol anions, respectively. These in situ formed clusters were endowed with not only homochirality via introducing R/SHftp2− and R/SH2btp3− ligands, but also rich oxo-bridges by controlling the hydrolysis of DyⅢ ions. Different anions from DyⅢ salts further induced structural variation between two sets of clusters. 1R and 1S feature an unprecedent four-blade propeller shaped {Dy18} core, whose centered octahedral {Dy6} unit are surrounded by four triangular {Dy3} units. Strikingly, they represent the second largest chiral 4f cluster species so far. 2R and 2S display a sandglass-like {Dy9} skeleton that consist of two square pyramid {Dy5} units sharing a DyⅢ vertex. Magnetic investigation revealed possible antiferromagnetic interactions between the DyⅢ centers in these clusters.
The unique structural features represented by micro-nanoneedle tip structure reflect wonderful physical and chemical properties. The tip effect includes the concentration of energy such as electrons, photons and magnetism in the tip region, which has promising applications in the fields of energy conversion, water capture, environmental restoration and so on. In this review, a comprehensive and systematic summary of the latest advances in the application of the tip effect in different fields is provided. Utilizing advanced Finite Difference Time Domain simulation, we further propose our understanding of the fundamental mechanism of the tip effect induced by micro-nanostructure. However, we need to forge the present study to further reveal the essential law of the tip effect from the perspective of theoretical calculations. This review would provide a solid foundation for further development and application of the tip effect.
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