Latest ArticlesDevelopment of adsorbent materials for highly efficient iodine capture is high demand from the perspective of ecological environment and human health. Herein, the two kinds of thiophene-based covalent organic frameworks (COFs) with different morphologies were synthesized by solvothermal reaction using thieno[3, 2-b]thiophene-2, 5-dicarbaldehyde (TT) as the aldehyde monomer and tri(4-aminophenyl)benzene (PB) or tris(4-aminophenyl)amine (PA) as the amino monomer (denoted as PB-TT COF and PA-TT COF) and the as-prepared two heteroatoms-rich COFs possessed many excellent properties, including high thermal stability and abundant binding sites. Among them, PB-TT COF exhibited ultra-high iodine uptake up to 5.97 g/g in vapor, surpassing most of adsorbents previously reported, which was ascribed to its high specific surface (1305.3 m2/g). Interestingly, PA-TT COF with low specific surface (48.6 m2/g) showed good adsorption ability for iodine in cyclohexane solution with uptake value of 750 mg/g, which was 2.38 times higher than that obtained with PB-TT COF due to its unique sheet-like morphology. Besides, the two COFs possessed good reusability, high selectivity and iodine retention ability. Based on experimental results, the adsorption mechanisms of both COFs were studied, revealing that iodine was captured by the physical-chemical adsorption. Furthermore, the both COFs showed excellent adsorption ability in real radioactive seawater treated safely, demonstrating their great potential in real environment.
A new biobased flame retardant (MHPA) with remarkable compatibility was synthesized via a facile and low-cost neutralization reaction of magnesium hydroxide (MH) and phytic acid (PA). By blending the prepared MHPA into ethylene vinyl acetate (EVA), the fire retardancy, smoke suppression and mechanical properties of the composites were significantly improved. When 50 wt% of MH was added into EVA matrix, the value of limiting oxygen index (LOI) reached 26.1%. Whereas, when 10 wt% MH in the EVA composites (with initial 50 wt% MH) was replaced by MHPA, the resulted EVA composites had a LOI value of 30.8%, indicating high efficiency of addition of MHPA to improve flame retardancy. Moreover, the heat release rate (HRR) and total smoke production (TSP) of the EVA composites reduced by 54.4% and 27.6%, respectively, suggesting that incorporation of MHPA could effectively hinder rapid degradation of EVA composites during burning process. The fire-retardant mechanism may reside in that the MHPA combined with MH can present the excellent carbonization and expansion effects. This study illustrates that the biobased MHPA has a broad application prospect to develop flame-retardant EVA composites.
A dual-readout sensing platform based on two signal transduction channels can integrate the unique advantages of each sensing pattern, compensate for the deficiency in the adaptive capacity, and enable a more convincing performance in analytical applications. Here, we introduce a responsive molecule dye, xylenol orange (XO), to combine with lanthanide terbium ions (Tb3+). The resultant Tb3+-XO complex exhibited tunable optical properties and was used as a novel colorimetric and luminometric dual-readout sensing platform for assaying the anthrax biomarker, dipicolinic acid (DPA). In the presence of Tb3+, the XO solution underwent a color change from yellow to magenta; however, upon adding DPA, the color changed back to yellow immediately, accompanied by the characteristic luminescence emission of Tb3+. Considering the strong affinity between DPA/XO and metal ions, the proposed sensing platform was further employed for the determination and differentiation of certain metal ions using linear discriminant analysis. This convenient dual-readout sensing platform offers several notable features and significantly promotes the application and development of lanthanide-based materials.
There is an urgent demand for tuning the selectivity and activity of the photocatalysts to remove co-existent pollutants simultaneously. Herein, we introduced the surficial activity sites into the bismuth oxybromide (BiOBr), including the Bi/Bi-O defects and hetero Cu atoms, and then the higher photocatalytic activity and selectivity of BiOBr were realized for degradation phenol and ciprofloxacin (CIP). It can be found that the Bi/Bi-O defects played more important role in enhancing the photocatalytic activity for degradation of phenol, while the Cu atoms significantly improved the photocatalytic activity for removing CIP. Moreover, the heterogeneous Cu atoms as the activity sites excited the reaction between phenol and CIP even under dark condition and were beneficial for synchronously removing phenol and CIP. This work provides a feasible way for BiOX photocatalyst to remove co-existent pollutants and may have a practical application.
To investigate the reactivity of homoatomic clusters [E9]4− (E = Si-Pb) and intermetalloid clusters [M@E9]−, the reactions of the Zintl anions [Sn9]4− and [Ni@Sn9]4− with the CdMes2 (Mes = Mesitylene) in the presence of 2.2.2-crypt were carried out. Two new compounds [K(2.2.2-crypt)]6[(Sn9)Cd(Sn9)].en (1) and [K(2.2.2-crypt)]6[(Ni@Sn9)Cd(Ni@Sn9)].en (2) were afforded. Both 1 and 2 were characterized by single-crystal X-ray diffraction, energy dispersive X-ray (EDX), and electrospray ionization mass spectrometry (ESI-MS), and can be viewed as two [Sn9]4− or [Ni@Sn9]4− subunits bridged by Cd ion in an η3: η3 coordination mode. Quantum chemical calculations reveal the relationships between the geometries and electronic structures of clusters 2a, [Ni3Ge18]4− and [Cu4@Sn18]4−. Further electron localization technique (AdNDP method) was performed to explain chemical bonding patterns of 1a.
Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable structures and synergistic properties is still on the way. Herein, we propose a simple and effective approach to create the multi-functional stimuli-responsive biomimetic devices with independently pre-programmable colorful visual patterns, complex geometries and morphable modes. The metal organic framework (MOF)-based composite film acts as a rigidity actuation substrate to support and mechanically guide the spatial configuration of the soft chiral nematic liquid crystal elastomer (CLCE) sheet. We can directly program the structural color of the CLCE sheet by adjusting the thickness distribution without tedious chemical modification. By using this coordination strategy, we fabricate an artificial flower, which exhibits a synergistic effect of both shape transformation and color change like paeonia 'Coral Sunset' at different flowering stages, and can even perform different flowering behaviors by bending, twisting and curling petals. The assembled bionic flower is innovatively demonstrated to respond to local stimuli of humidity, heat or ultraviolet irradiation. Therefore, the spatial assembly of CLCE combined with functional MOF materials has a wide range of potential application in multi-functional integrated artificial systems.
We present the synthesis, characterization and photoluminescence properties of uranium-containing selenotungstate, [(UO2)3(SeO3)3Na5(H2O)6(SeW6O21)(SeW9O33)3]21–, which was isolated by a one-pot reaction of uranium nitrate with sodium tungstate and sodium selenite in a pH 5.2 aqueous solution at 90 ℃. In this study, the effect of the introduction of lone-electron pair containing heteroatoms on the structure is demonstrated, a three-layered heterometallic {Se3U3Na5} cluster is encapsulated by two different anionic building block units: three trivacant Keggin {B-α-SeW9O33} and one Anderson {SeW6O21}. To our knowledge, the {Se3U3Na5} cluster has never been observed in the polyoxometalate chemistry. The solid-state photoluminescence properties and lifetime decay behaviours of the title compound (1) have been measured at room temperature, and the photoluminescence spectrum displays the characteristic emission bands of corresponding uranyl cations. In addition, the photoluminescence quantum yield of 1 is 72%, which is almost three times that of starting material UO2(NO3)2.6H2O (27%). By using this strategy, we envision that an increasing number of assemblies with 'open' clusters may be designed and obtained, in which the exposed oxygen atoms show strong affinity towards metal ions, providing new opportunities to generate bigger clusters or to tune existing properties.
The production of CH3COOH from CO2 and CH4 has stimulated much interest due to the high energy density of C2 species. Various kinds of catalysts have been developed while the high dissociation barrier of CH4 and low selectivity still hinders the efficiency of the reaction. We have herein proposed a novel catalyst with single metals loaded on 2D BC3N2 substrate (M@2D-BC3N2) based on density functional theory. Among numerous candidates, Pt@2D-BC3N2 possesses the most favorable reactivity with an ultralow barrier of CH4 splitting (0.26 eV), which is due to the efficient capture ability of CH4 on Pt site. Besides, the selectivity for CH3COOH is also very high, which mainly stems from the unique electronic properties of molecules and substrate: The degenerated states, including s, px, py and pz, in CO2 reflects the existence of delocalized π bonds between C and O. This can interact with states of Pt(s), Pt(pz), Pt(dxz), Pt(dyz), and Pt(z2) in Pt@2D-BC3N2. The kinetics model also proves that our system can promote CH3COOH production via simply increasing the temperature or the coverage of CH4 and CO2. Our results provide a reasonable illustration in clarifying mechanism and propose promising candidates with high reactivity for further study.
Herein, phosphorus-mediated sulfur nanoparticles encapsulated in reduced graphene oxide nanosheets (P-SrGO-T) were successfully synthesized as the cathode for sodium ion battery by a ball milling and the following thermal treatment. A series of covalent bonds, such as P–S, C–S–C, C–O–P and C–S–P, are formed in this process, which are in favor of fixing the sulfur and suppressing the parasitic shuttle effect of polysulfide. Benefiting from the graphene sheets and these covalent bonds, a high reversible capacity of 637.4 mAh/g was achieved in P-SrGO-T after 100 cycles at the current density of 0.2 A/g. In addition, P-SrGO-T also delivers a high-rate capacity (330.7 mAh/g at 5 A/g) attributing to low charge transfer resistance and faster ion diffusion kinetic. This work pushes the progress forward in developing phosphosulfide cathode for sodium ion batteries.
Formic acid decomposition (FAD) is considered a promising hydrogen production route to facilitate the ambient storage and on demand release of hydrogen energy. To optimize the catalysts for FAD, efforts have been paid to explore the underlying reason for the varied catalytic activity among catalysts with similar composition but differed structure. However, such endeavors are highly challenging due to the deeply intermingled effects of electronic structure, particle size, and facets, etc. Herein, to separately evaluate the respective effects of these factors, a series of catalysts with the same surface electronic structure and different particle size was prepared by cation dipole adjustment method. The performance and characterization results showed that the catalysts with different sizes and facets exhibited similar intrinsic activity with deviation of less than 5%. However, they showed 252% deviation of site stability, indicating that only the optimized electronic structure could enhance the intrinsic activity and a smaller particle size could extend the catalyst's life.
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