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As the desired sulfur host of lithium-sulfur battery, the strong polarity and fast electron migration capability are indispensable for achieving effective adsorption and conversion of lithium polysulfides (LiPSs), that is, restricting the shuttle effect. Herein a porous microdisk Ti4O7/TiN/C heterojunction with strong polar N-Ti-O covalent bonds is precisely constructed. Compared with O-Ti-O or N-Ti-N bond in single Ti4O7 or TiN, the N-Ti-O bond with stronger polarity could adsorb and bond with S and Li atoms in LiPSs, which is beneficial for LiPSs adsorption. Beside, the Ti4O7/TiN heterostructure favors the electron transfer, which could promote the conversion of LiPSs. The design strategy is to construct abundant polar N-Ti-O bonds at Ti4O7/TiN heterogeneous interface that would realize the associative process of LiPSs adsorption, trapping, and conversion, thereby restraining the shuttle effect efficiently. In the current study, as the host of the sulfur cathode, the porous microdisk TiN/Ti4O7/C heterojunction exhibits a high specific capacity of 1204.5 mAh g−1 at 0.2 C, and a high specific capacity of 616.5 mAh g−1 at an ultrahigh current density of 4 C. In addition, 86.4% and 116.9% capacity are retained over 1000 cycles at 1 C and 2 C, respectively. This strategy provides an insight into developing lithium-sulfur battery with extraordinary performance, and opens promising routes to design the next-generation electrochemical energy storage devices.

The high specific capacity of metal oxides cannot cover up their low electron and ion diffusion rate and large volume expansion as anodes of lithium-ion batteries.

Abstract: Drug polymorphism is an important factor affecting the drugs quality and clinical effica-cy. Therefore, great attention should be paid to the crystal analysis of drugs with their researching and evaluating part. With the booming development of Raman spectroscopy in recent years, more and more crystal analysis investigations were based on vibrational spectroscopy. This review main-ly discussed the qualitative and quantitative analysis of active pharmaceutical ingredients (API) and pharmaceutical preparation with Raman spectroscopy. On basis of the determination of the vibra-tion mode of drug molecules and the analysis of their chemical structure, this method had the ad-vantages of universal, non-destructive, fast determination, low samples and cost, etc. This review provides theoretical and technical support for crystal structure, which are worth popularizing. It is expected that it will be helpful to relevant government management institutions, pharmaceutical sci-entific research institutions and pharmaceutical manufacturers.

Engineering MXene-based 2D heterostructures is a hot research topic for capacitive deionization (CDI) materials. Herein, MXene nanosheets were ingeniously integrated with metal-organic frameworks (MOFs)-derived carbons to generate the N, P-doped...

TiAl alloys are difficult to obtain high density through traditional pressing and sintering process. Sn is a promising liquid-phase sintering addition for TiAl alloys; however, the further studies have elaborated that the liquid phase sintering of Sn is limited due to poor wettability between TiAl and melt Sn. Based on it, this study adopts Sn–Al powder addition instead of pure Sn powder. The results describe that a small amount of active Al enhanced the wettability of the Sn droplets to the TiAl matrix, thereby further promoting the liquid phase sintering effect of the addition of Sn. The sample sintered at 1320–1350 °C has a density excess of 95%, near γ or duplex microstructure with small proportion of lamellar colonies. Through subsequent non-encapsulation HIP, the fine-grained structure is maintained at the same time to reach full density, which enables the as-sintered samples to obtain moderate tensile properties at room temperatures (UST = 520 ± 5 MPa, YS = 401 ± 7 MPa, EL = 1.33 ± 0.1).

Sensitive, accurate, and simultaneous determination of nitrobenzene compounds (NBs) in environmental water samples is of great significance due to their high risk to human health. In this work, a new triazine-based hyper-crosslinked polymer named CC-Py was constructed via the Friedel-Crafts reaction between cyanuric chloride (CC), pyridine (Py) and 1,2-dichloroethane. Due to its excellent stability, high surface area and hydrophilic-lipophilic (amphiphilic) structure, the CC-Py exhibited a high affinity toward the NBs (nitrobenzene, 2-nitrotoluene, 2,6-dimethylnitrobenzene, 3-nitrotoluene, 4-nitrotoluene, 3-nitrochlorobenzene, 4-nitrochlorobenzene, 2-nitrochlorobenzene, 2,4-dimethylnitrobenzene, 3-nitrobromobenzene, 4-nitrobromobenzene and 4-nitroiodobenzene). Then, a CC-Py based solid-phase microextraction coupled with gas chromatography-flame ionization detection was developed to detect the twelve NBs in real water samples. The results showed that the method had low limits of detection (0.20-0.50 μg L

The Songliao Basin is the largest Early Cretaceous lacustrine rift basin of northeast China and hosts tremendous conventional and unconventional petroleum resources. However, the distribution of shale oil is not well constrained, as production from source rock reservoirs requires certain thermal maturity cut-offs (vitrinite reflectance of > 0.8%Rr). In this study, the thermal maturity of the Qiangshankou Formation along the Southern Uplift and in the Central Depression of the Songliao Basin was evaluated by combining traditional and advanced petrographic and geochemical maturity proxies with clay mineralogical investigations. The Qingshankou Formation is one of the major source rocks of the region, but previous studies encountered difficulties in obtaining reliable maturity data, mainly due to strongly shifted Tmax values. Equally, Tmax determined during this study showed apparent shifting likely caused either by retained solid bitumen or by variations in kerogen type. In contrast, the measured vitrinite reflectance shows a reliable depth trend, meeting the shale oil cut-off maturity of 0.8%Ro at a drilling depth of ~ 2300 m, which is only reached in the Central Depression of the basin. The vitrinite reflectance trend is supported by changes in clay mineralogy, such as the progressing ordering of I/S mixed layers (“Reichweite”), increasing illitization, decreasing detrital kaolinite and correspondingly increasing authigenic chlorite contents. Maturity-related biomarker proxies are only partly valid; while the methylphenanthrene index (MPI-1) and the trimethylnaphthalene ratio (TNR-1) show reliable maturity trends even over short depth intervals, other established proxies (e.g. based on alkylbiphenyls) proved insensitive to changes from immature to peak oil mature and are, therefore, not recommended for further use in studies on Qingshankou Fm. shales. In summary, the combination of various maturity parameters improves the understanding of shale oil distribution in the central Songliao Basin, providing valuable insights for studies on similar unconventional targets in the region.

Metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs) are promising precursors for preparing high-performance carbonaceous materials for capacitive deionization (CDI). However, the...

The large surface area, adjustable pore structure, good thermal and chemical stabilities, and abundant π-electron systems make triazine-based porous organic polymers (TPOPs) as promising porous materials for gas storage, catalysis, energy conversion and adsorption. Recently, TPOPs have aroused ever-increasing interest and are considered as one of the research highlights in solid phase microextraction (SPME) and other sample pretreatment techniques. This minireview summarizes the recent advancements in the synthesis of TPOPs and their applications in SPME. The application prospects of the TPOPs in SPME and other sample pretreatment techniques are also presented.

Metal oxides/sulfides have been considered as promising anode candidates for use in next-generation lithium-ion batteries (LIBs), but the large volume changes and poor electron and ion conductivities limit their practical applications. Here, twin-born Fe3O4/FeS/carbon nanosheets (TB-FeOSC-NS) were precisely fabricated for the first time by using MIL-88b(Fe) as a self-sacrificing template. By adjusting the amount of citric acid and the annealing temperature, the structure and phase composition could be accurately controlled. Benefitting from its unique structure, TB-FeOSC-NS can provide an abundant contact interface with electrolytes and active sites for redox reactions, providing a short diffusion path for electrons and ions. Therefore, as an anode material for use in LIBs, the TB-FeOSC-NS electrode exhibits admirable electrochemical performance, including a high specific capacity, excellent cycling stability, and superior rate performance, with a high capacity of 400 mA h g−1 at an ultrahigh current density of 20 A g−1. More importantly, this work deepens our understanding of the precise synthesis of heterostructured materials for electrochemical energy storage and the synergistic modulation of morphologies, phase compositions, and interfaces.

Capacitive deionization (CDI) provides a promising option for affordable freshwater while simultaneously storing energy, but its large-scale application is usually limited owing to the poor performance of conventional materials in natural (oxygenated) saline water. Herein, we report heterointerface optimization in a covalent organic framework (COF)-on-MXene heterostructure achieving a high CDI performance for desalination of oxygenated saline water. The 2D heterostructure with the optimal core-shell architecture inherits the high conductivity and reversible ion intercalation/deintercalation ability of MXene, and the hierarchical porous structure, large porosity, and extraordinary redox capacity of COFs. Thanks to the heterointerface optimization, the MXene@COF heterostructure exhibits a very stable cycling performance over 100 CDI cycles with a maximum NaCl adsorption capacity of 53.1 mg g

Herein, we introduce a modulation strategy for the synthesis of imine based covalent organic frameworks (COFs) via the condensation of benzene-1,3,5-tricarbaldehyde with 1,3,5-tris (4-aminophenyl) benzene, whereby aniline was adopted as the monofunctional competitor. The introduction of aniline resulted in an enhanced crystallinity, surface area and pore volume, which is beneficial for the enrichment capability of the resulting COFs for the analytes. The optimized COF with the best extraction ability was selected as the solid phase microextraction (SPME) fiber coating for the extraction of polycyclic aromatic hydrocarbons (PAHs) from honey samples. The adsorbed PAHs were then analyzed by gas chromatography with mass spectrometric detection. The merits for the method include: (a) low limits of detection (0.06–0.17 ng/g, S/N = 3), (b) high enrichment factors (290-1566-fold), good reproducibility (relative standard deviations less than 8.4%) and excellent method recoveries for the PAHs (83.0%–116.0%). The enrichment performance of the COFs towards the PAHs could be attributed to the hydrophobic interaction, the high surface area and pore volume of the COF materials.

The synthesis of high-performance porous carbon materials via carbonization of environment-friendly biomass fits perfectly with the concepts of sustainability and green chemistry. Herein, we report...

The modification of separators with transition metal compounds is an effective strategy to alleviate the shuttle effect of polysulfides in lithium–sulfur (Li–S) batteries. Herein, a novel interlaye...

Constructing heterostructures with advanced architectures is an effective strategy for enhancing the crystallinity and functional performance of covalent organic frameworks (COFs). Herein, a novel core-shell heterostructure integrating a metal-organic framework (MOF)-derived graphitic carbon core (GC) and a well-arranged COF shell, termed MOF-GC@COF, is reported. ZIF-67 dodecahedra are first chemically etched with a weak organic acid and further converted to MOF-GC via thermal pyrolysis. In the subsequent step, β-ketoenamine-linked COF nanofibers are vertically assembled on the surface of the MOF-GC cores to generate the MOF-GC@COF heterostructure. As a proof-of-concept application, the as-prepared MOF-GC@COF heterostructure is used as an effective quartz crystal microbalance (QCM) sensor for the adsorption of formaldehyde. Benefiting from the synergistic effect of the hybrid composition and the advantages of the core-shell heterostructure, the newly prepared MOF-GC@COF heterostructure exhibits excellent sensing performance toward formaldehyde with rapid adsorption kinetics, high sensitivity, and superior selectivity.

Owing to various health threats associated with phthalic acid esters (PAEs), this category of endocrine-disrupting compounds has attracted more and more public scrutiny. However, the efficient preconcentration of PAEs from complex food-contacted plastics still remains challenging. Herein, three covalent triazine-based frameworks (CTFs) were constructed by facile Friedel-Crafts reactions of cyanuric chloride (CC), with triptycene (TPC), fluorene (FL) and 1,3,5-triphenylbenzene (TPB), respectively. Three CTFs were then employed as solid-phase microextraction (SPME) coatings for the extraction of PAEs. Benefiting from the large surface area and high pore volume, the newly-synthesized CC-TPC based SPME method exhibited large enrichment factors (978-2210), low limits of detection (0.027-0.10 ng g

A triazine-based conjugated microporous polymer (TCMP) was generated by introduced 1, 3, 5-triazine into conjugated microporous polymer network via Friedel-Crafts reaction. Under the optimum synthesis conditions, the obtained TCMP has a loose and porous structure. It was then used as a fiber coating material for solid-phase microextraction (SPME) of halogens-containing environmental hormones. It showed a strong adsorption capability due to the halogen bond, electrostatic, π-π stacking and hydrophobicity interactions. An analytical method combining the TCMP coated fiber-based SPME with gas chromatography-electron capture detection was developed to determine twelve halogens-containing environmental hormones in vegetable and fruit samples. A wide linear range (0.07-100.0 ng g

Organic micropollutants (OMPs) in water resources are a growing threat to aquatic ecosystems and human health. Efficient removal of polar OMPs is very challenging because of their high hydrophility. Synthesizing novel adsorbent capable of high-efficiently removing hydrophilic and hydrophobic micropollutants is highly desirable for water remediation. Here, using natural proanthocyanidin as building units, a novel hydroxyl-functional porous organic framework (denoted as PC-POF) with amphiphilic feature was synthesized through facile azo coupling reaction. Five sulfonamide antibiotics were selected as model OMPs for adsorption study. Adsorption experiments demonstrated a more rapid and efficient sulfonamides capture ability of the PC-POF than that of the most reported adsorbents due to strong hydrogen bonding, π stacking and electrostatic interactions. The PC-POF can be easily recovered and reused at least 5 times without obvious decline in adsorption performance. Moreover, experiments conducted at environmentally relevant concentrations (μg L

A covalent organic framework named N-COF was successfully constructed by the aldehyde-amine condensation reaction between 2,4,6-tris (4-formyl phenoxy)-1,3,5-triazine and 1,3-bis(4-aminophenyl) urea for the first time. The prepared N-COF exhibited good stability and high affinity to organochlorine pesticides (OCPs). Thus, the N-COF was served as solid phase microextraction fiber coating for extraction of six OCPs from vegetables and fruits including romaine lettuce, cabbage, Chinese cabbage, apple, pear and peach, followed by quantitation with gas chromatography-electron capture detector (GC-ECD). Under the optimal conditions, good linearities for the OCPs existed in the ranges from 0.1 to 1.0 ng g

Advancement of novel coating materials for solid-phase microextraction is highly needed for sample pretreatment. Herein, a triazine-based covalent organic polymer was constructed from the monomers of cyanuric chloride and trans-stilbene via the Friedel-Crafts reaction and thereafter used as a solid-phase microextraction fiber coating for the extraction of polycyclic aromatic hydrocarbons and their nitrated and oxygenated derivatives. The newly-developed solid-phase microextraction method coupled with gas chromatography/flame ionization detection gives enhancement factors of 548-1236 and limits of detection of 0.40-2.81 ng/L for the determination of polycyclic aromatic hydrocarbons and their derivatives. The one fiber precision for five replicate determinations of the analytes and the fiber-to-fiber precision with three parallel prepared fibers, expressed as relative standard deviations, was in the range of 4.6-9.4% and 6.2-10.9%, respectively. The relative recoveries of the analytes for environmental water samples were in the range of 88.6-106.4% with the relative standard deviations ranging from 4.0 to 11.7% (n = 5).

The large surface area, adjustable pore structure, good thermal and chemical stabilities, and abundant

Although graphene nanomesh is an attractive 2D carbon material, general synthetic routes to produce functional graphene nanomesh in large-scale are complex and tedious. Herein, we elaborately design a simple two-step dimensional reduction strategy for exploring nitrogen-doped graphene nanomesh by thermal exfoliation of crystal- and shape-modified metal-organic frameworks (MOFs). MOF nanoleaves with 2D rather than 3D crystal structure are used as the precursor, which are further thermally unraveled into nitrogen-doped graphene nanomesh by using metal chlorides as the exfoliators and etching agent. The nitrogen-doped graphene nanomesh has a unique ultrathin two-dimensional morphology, high porosity, rich and accessible nitrogen-doped active sites, and defective graphene edges, contributing to an unprecedented catalytic activity for the oxygen reduction reaction (ORR) in acid electrolytes. This approach is suitable for scalable production.

A porous aromatic framework (PAF), PAF-56P, with a large surface area, high solvent stability and good thermostability, was prepared and utilized as a solid phase microextraction (SPME) adsorbent coating for the efficient enrichment of some triazole fungicides. Coupled with gas chromatography-mass spectrometric detection, a PAF-56P based SPME method achieved good analytical performance such as low limits of detection (0.15–1.70 ng g−1), wide linear range (2.50–250 ng g−1) and good repeatability (relative standard deviations, RSDs < 9.2%). The PAF-56P SPME coating had a high durability for 100 replicate extractions without a significant decrease in extraction capability. The developed method was feasible for the analysis of triazole fungicides from fruits and vegetables with satisfactory recoveries (81.3–119%).

This study proposes the construction of nanoporous poly-melamine-formaldehyde (PMF) through the Schiff base condensation reaction of paraformaldehyde and melamine. The PMF nanoparticles showed a good adsorption capability to some benzene-ring-containing dyes including acid fuchsine, nigrosine, and methyl orange. Moreover, the as-prepared PMF nanoparticles were employed as the coating adsorbent for the solid-phase microextraction (SPME) of seven volatile fatty acids (VFAs) with high enrichment factors. A PMF-assisted SPME method was established for the enrichment of VFAs from environmental water samples with satisfactory recoveries (88.5%-102.0%) and acceptable precisions (relative standard deviations

Metallic molybdenum disulfide (MoS2) has attracted wide attention owing to its high electrical conductivity and promising application in the electrocatalytic hydrogen evolution reaction (HER). However, it is difficult to realize the scale-up production of thermodynamically metastable metallic MoS2via conventional approaches. Although some research efforts have been devoted to producing metallic MoS2, it is still a challenging task to simultaneously realize metallic phase control and morphological regulation in MoS2. Here, metallic MoS2 with a controllable hierarchical spherical structure has been achieved via a hydrothermal strategy by using carbon nitride (C3N4) nanospheres as a self-sacrificial template. In the crystal growth, C3N4 played an important role in controlling the morphology of MoS2 by serving as the nucleation and growth site. Meanwhile, the decomposed C3N4 acted as an intercalated material which could further stabilize the metallic phase MoS2. Owing to good electroconductibility and unique structure design, metallic phase MoS2 with a hierarchical flower-like architecture exhibits enhanced electrolytic properties for the HER in an acidic medium.

A novel nanoporous carbon (NPC) was constructed by utilizing the porous aromatic framework-6 (PAF-6) as both the template and carbon source along with KOH as a chemical activator. The newly-synthesized PAF-6 derived nanoporous carbon (PAF-6-NPC) was then employed as a solid-phase microextraction (SPME) fiber coating. Coupled with gas chromatography-flame ionization detection, the PAF-6-NPC fiber-based SPME method exhibited large enhancement factors, low limits of detection, good linearity and acceptable repeatability for the determination of some n-alkanes in various water and soil samples. The method recoveries for the n-alkanes were in the range of 89.5–102.9% for water and 86.0–104.5% for soil samples, respectively. The PAF-6-NPC coated fiber showed no obvious decrease of the extraction efficiency for the analytes after 100 replicate extractions. The PAF-6-NPC fiber-based SPME method was successfully applied for the determination of n-alkanes in water and soil samples.