Phosphine-based covalent organic framework for highly efficient iodine capture

Highly efficient and reversible iodine capture utilizing amorphous conjugated covalent triazine-based porous polymers: Experimental and computational studies

Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels’ applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

Functional porous organic polymer with high S and N for reversible iodine capture

亚胺类共价有机骨架(I-COFs)是有机单体根据席夫碱(Schiff-base)反应原理缩合形成的一类新型多孔晶体有机材料。I-COFs具有骨架密度低、比表面积大、孔隙率高、单体种类丰富、孔径尺寸可控、结构可功能化、合成方法多样和物化稳定性好等优点。近年来,I-COFs已成为材料科学领域的研究前沿,并广泛用于气体吸附、存储、催化、传感、光电材料等方面。I-COFs材料优异的物理化学性能使其非常适于用作复杂样品中痕量目标物的分离富集介质,其高比表面积、高孔隙率性能赋予了它极高的吸附负载量,这些性能使得目标分析物可被高效富集;通过控制有机单体的链段长度、几何结构、掺杂元素、取代基团等方面精确调控I-COFs的孔洞结构和功能化基团,从而实现目标痕量物质的选择性富集。目前,I-COFs材料在样品前处理领域作为新型萃取介质已引起了极大关注。该文综述了近年来I-COFs材料的主要类型、合成方法及其在固相萃取、磁性固相萃取、分散固相萃取和固相微萃取方面的研究进展,同时展望了I-COFs在样品前处理领域的发展前景。

Solvothermal synthesis and characterization of anatase TiO 2 nanocrystals with ultrahigh surface area

Structural properties of alumina supported Ce–Mn solid solutions and their markedly enhanced catalytic activity for CO oxidation

Chiral covalent organic framework-based open tubular capillary electrochromatography column for enantioseparation of selected amino acids and pesticides.

The high capacity of Ni-rich Li[Ni(1-x)M(x)]O(2) (M = Co, Mn) is very attractive, if the structural instability and thermal properties are improved. Li[Ni(0.5)Mn(0.5)]O(2) has good thermal and structural stabilities, but it has a low capacity and rate capability relative to the Ni-rich Li[Ni(1-x)M(x)]O(2). We synthesized a spherical core-shell structure with a high capacity (from the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) core) and a good thermal stability (from the Li[Ni(0.5)Mn(0.5)]O(2) shell). This report is about the microscale spherical core-shell structure, that is, Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) as the core and a Li[Ni(0.5)Mn(0.5)]O(2) as the shell. A high capacity was delivered from the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) core, and a high thermal stability was achieved by the Li[Ni(0.5)Mn(0.5)]O(2) shell. The core-shell structured Li[(Ni(0.8)Co(0.1)Mn(0.1))(0.8)(Ni(0.5)Mn(0.5))(0.2)]O(2)/carbon cell had a superior cyclability and thermal stability relative to the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) at the 1 C rate for 500 cycles. The core-shell structured Li[(Ni(0.8)Co(0.1)Mn(0.1))(0.8)(Ni(0.5)Mn(0.5))(0.2)]O(2) as a new positive electrode material is a significant breakthrough in the development of high-capacity lithium batteries.

Fish scale waste can be used as a precursor of hydroxyapatite (HAp). In this work, HAp was extracted from white seabass ( Lates calcarifer ) scale waste by using an alkali heat treatment. The fish scale was pretreated with hydrochloric acid (HCl) concentrations of 0.1, 0.5, and 1 M. The pretreated fish scale was then treated with 2% sodium hydroxide (NaOH) solution at 70°C for 5 h and again (20% NaOH solution) for 1 h to extract HAp. The effects of each pretreatment on the properties of the extracted HAp were investigated. HAp produced after pretreatment with 1 M HCl had the smallest particle size (28.24 ± 5.20 μm), the highest degree of crystallinity (79%), the highest thermal stability, the largest BET surface area (90.80 m 2 /g), and the highest whiteness value (97.360 ± 0.01). 1 M HCl could eliminate more protein, collagen, and other organic compounds than lower HCl concentrations without destroying the crystalline domains of the fish scale. Waste L. calcarifer scale is therefore a potential source of HAp. Furthermore, in a preliminary study for further research, HAp extracted in the proposed procedure was used as a filler in a biodegradable starch foam.

Construction of hypercrosslinked polymers with dual nitrogen-enriched building blocks for efficient iodine capture

Ultrafine Bi2WO6 nanoparticles prepared by flame spray pyrolysis for selective acetone gas-sensing

This work demonstrated that mesoporous TiO2 (meso-TiO2) with controllable mesoporous and crystalline structures can be facilely prepared by using poly (ethylene glycol) (PEG) as structure-directing (SD) agent and peroxotitanic acid (PTA) as precursor. Meso-TiO2 with high specific surface area (157 m2∙g-1), pore volume (0.45 cm3∙g-1) and large mesopore size of 13.9 nm can be obtained after calcination at 450°C. Such meso-TiO2 also shows relatively high thermal stability. BET surface area still reaches 114 m2∙g-1 after calcination at 550°C. In the synthesis and calcination process, PEG that plays multiple and important roles in delivering thermally stable and tunable mesoporous and crystalline structures shows to be a suitable low-cost SD agent for the controllable preparation of nanocrystalline meso-TiO2. The photocatalytic activity tests show that both high surface area and bi-crystallinity of obtained meso-TiO2 are important in enhancing the performance in photo-decomposing Rhodamine B in water.

A facile strategy to correlate the thermal decomposition of inorganic–organic hybrid with the Kirkendall effect appearing during the oxidation process of sulfides into oxides has been developed to synthesize hierarchical-porous-structured metal oxide microspheres by using ceria as the model system. The as-prepared hierarchical-porous-structured ceria with micropores, mesopores and macropores (HC3M) possesses a very high surface area (over 290 m2 g−1) and high thermal stability. We have also demonstrated that the pore size of mesopores in HC3M can be modulated by controlling the oxidation and decomposition temperature of the hybrid precursors. Our preliminary results of the preferential oxidation of carbon monoxide in the H2-rich stream (PROX) show that both the conversion and selectivity of the Cu/HC3M catalyst are obviously higher than those of Cu/CeO2 particles. The improved catalytic activity may be attributed to the high dispersion and the smaller size of Cu on HC3M, the high specific surface area and unique hierarchical porous structure of HC3M support. Thus, the hierarchical-porous-structured ceria is expected to find promising applications in catalysis, sensors and fuel cells. In addition, the method to convert inorganic–organic hybrid sulfides into oxides can be successfully extended to the synthesis of hierarchical-porous-structured Y-doped and La-doped ceria with the modulated composition. Through the designed preparation of inorganic–organic hybrid sulfides, selenides or tellurides followed by the oxidation and thermal decomposition at suitable temperature, we believe that this conversion of hybrid materials into oxides might be extended to fabricate other hierarchical-porous-structured oxides with improved physical and/or chemical properties.

The heterogeneous and multifunctional charged polymers have broad application prospects in modern catalysis. One of the valid methods of synthesizing multifunctional charged polymers is incorporating metalloporphyrins with halide anions. Herein, a series of zinc(II)porphyrin-based porous ionic polymers [PIP-ZnTIPP/DVB (1:m) (m = 20, 40, 60, 80)] were synthesized by combining imidazolium-functionalized Zn-porphyrin (ZnTIPP) and divinylbenzene (DVB) through the free-radical copolymerization by a solvothermal method. The rigid PIPs have many physical advantages such as spatial separation of Zn-porphyrin sites, high thermal stability, hierarchical pore structures, high specific surface area, and abundant imidazolium (Br–) group in the polymeric skeletons, which exhibit fantastic catalytic activity for the coupling reaction of epoxides and CO2 without any solvent or cocatalyst. In particular, the catalyst PIP-ZnTIPP/DVB (1:20) displayed the highest catalytic activity with a yield of 99% and a turnover frequency (TOF) of 759 h–1 and could be recycled six times without the loss of activity. The excellent catalytic activity results from a synergistic effect between zinc sites and nucleophilic bromide anions.

The capture of radioactive I2 vapor from nuclear waste under industrial operating conditions remains a challenging task, as the practical industrial conditions of high temperature (≥150 °C) and low I2 concentration (∼150 ppmv) are unfavorable for I2 adsorption. We report a novel guanidinium-based covalent organic framework (COF), termed TGDM, which can efficiently capture I2 under industrial operating conditions. At 150 °C and 150 ppmv I2, TGDM exhibits an I2 uptake of ∼30 wt %, which is significantly higher than that of the industrial silver-based adsorbents such as Ag@MOR (17 wt %) currently used in the nuclear fuel reprocessing industry. Characterization and theoretical calculations indicate that among the multiple types of adsorption sites in TGDM, only ionic sites can bond to I2 through strong Coulomb interactions under harsh conditions. The abundant ionic groups of TGDM account for its superior I2 capture performance compared to various benchmark adsorbents. In addition, TGDM exhibits exceptionally high chemical and thermal stabilities that fully meet the requirements of practical radioactive I2 capture (high-temperature, humid, and acidic environment) and differentiate it from other ionic COFs. Furthermore, TGDM has excellent recyclability and low cost, which are unavailable for the current industrial silver-based adsorbents. These advantages make TGDM a promising candidate for capturing I2 vapor during nuclear fuel reprocessing. This strategy of incorporating chemically stable ionic guanidine moieties in COF would stimulate the development of new adsorbents for I2 capture and related applications.