Search

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.

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).

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

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.

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.

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.

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.

Two-dimensional (2D) nanosheets are promising electrode materials for electrochemical desalination by capacitive deionization (CDI). Like most 2D nanosheets, the delicate design of MXene-based materials can achieve state-of-the-art desalination capacities, but the intrinsic low ion diffusion characteristic of 2D nanosheets limits the desalination rate. To address this problem, we synthesize a new-family of nitrogen-doped three-dimensional (3D) nanofibrous architectures from MXenes (denoted as N-TNF) via direct alkalization and subsequent nitrogenization of common MXene stacks. N-TNF has a unique nanofiber structure and plentiful nitrogen dopants, resulting in expanded interlayer spacing, high specific surface area and excellent electrochemical activity. As a result, the N-TNF shows an ultrahigh mean desalination rate of 5.6 mg g−1 min−1, along with superior desalination capacity of 44.8 mg g−1, as well as good long-term cycling stability, which is comparable to state-of-the-art MXene electrodes and better than most 2D materials. This work demonstrates the fabrication of MXene-derived 3D materials, and provides a new approach to overcome the limits of 2D nanosheets for efficient CDI.

By integration of benzene-constructed porous organic polymer (KBF) and multiwalled carbon nanotube (MWCNT), a MWCNT-KBF hybrid material was constructed through in situ knitting benzene with formaldehyde dimethyl acetal in the presence of MWCNTs to form a network. MWCNT-KBF was then adopted as a novel solid-phase microextraction (SPME) fiber coating. Coupled to gas chromatography-flame ionization detection, the MWCNT-KBF–assisted SPME method showed large enhancement factors (483–2066), low limits of detection (0.04–0.12 μg L−1), good linearity (0.13–50 μg L−1), and acceptable reproducibility (4.2–10.2%) for the determination of polycyclic aromatic hydrocarbons (PAHs). The method recoveries of seven PAHs were in the range 80.1–116.3%, with relative standard deviations (RSDs) ranging from 3.5 to 11.9%. The SPME method was successfully applied to the determination of PAHs in river, pond, rain, and waste water, providing a good alternative for monitoring trace level of PAHs in environmental water.

A hybrid composite featuring an iron-based metal-organic framework Material of Institute Lavoisier-88(Fe) and graphene oxide (MIL-88(Fe)/GO) was synthesized and used as the solid-phase microextraction (SPME) coating. The SPME fiber was prepared by covalent bonding of the MIL-88(Fe)/GO composite onto the stainless steel substrate. The fiber had a good durability and allowed >100 replicate extractions. The developed method, which combined the MIL-88(Fe)/GO coated fiber based SPME with gas chromatography-flame ionization detection (GC-FID), achieved low limits of detection (0.5–2.0 ng g−1, S/N = 3) and good linearity (r2 > 0.994) for the phthalic acid esters (PAEs) from various vegetable oil samples. The repeatability and fiber-to-fiber reproducibility were in the range of 4.0–9.1% and 5.7–11.4%, respectively. The method was successfully applied to the analysis of PAEs from vegetable oil samples with good recoveries (83.1–104.1%) and satisfactory precisions (RSDs

Designing low-cost oxygen reduction reaction (ORR) electrocatalysts to replace platinum group metal holds great promise for boosting the wide use of metal-air batteries. Herein, atomically dispersed iron supported on nitrogen-doped carbon (A-Fe-NC) was fabricated via an effective ligand-stabilized pyrolysis strategy. Owing to the high density of the active sites and the two-dimensional (2-D) nanosheet structure, the as-prepared A-Fe-NC electrocatalyst delivers excellent ORR performance with a positive half-wave potential of 0.865 V in alkaline solution, which is superior to that of Pt/C (0.82 V vs RHE). Moreover, the primary Zn-air battery assembled with the A-Fe-NC delivered an ultrahigh specific power of 132.2 mW cm−2 and stable long-term operation. It also displayed robust charging-discharging cycling performance with voltage gap of 0.83 V after 240 h, lower than that of the Pt/C + RuO2 electrode (0.95 V). To reveal the catalytic mechanism of A-Fe-NC, density functional theory calculation was conducted and the results revealed that the interaction between Fe and nitrogen regulated the electronic structure of active sites, thus improving charge transfer and further promoting the electrocatalytic reactivity for ORR. This work provided a facile and effective strategy for constructing Fe/N codoped 2-D carbon nanocomposite as high performance electrocatalysts for energy conversion.

Microfluidic contact lenses (MCLs) for continuous intraocular pressure (IOP) monitoring are promising devices for the diagnosis and management of glaucoma. Here, we present an ultra-sensitive and cost-effective MCL for IOP monitoring. A folding method that allows 2D-to-3D transformation of a planar microchannel is introduced. An ultra-sensitive serpentine microchannel of notched-ring configuration is designed in coordination with the folding method. The optimization of the microchannel geometry is performed through numerical simulations and experiments. The performance of the device is evaluated using a hemispherical silicone model eye. The sensitivity of the MCL reaches up to 0.825°/μl, which clearly exceeds the existing MCLs. Moreover, stair-case and cyclical tests are performed to confirm the device's recoverability and repeatability. These results prove that the proposed MCL is a suitable selection for intraocular pressure monitoring.

Covalent organic frameworks (COFs) have attracted great research interest due to their fascinating structures and potential applications in various fields. Here, the COF-SCU1 (SCU for Sichuan University) coated solid-phase microextraction (SPME) fibers were fabricated by coating it on prior functionalized stainless steel wires via a simple physical coating method, and applied to extract some volatile benzene homologues from indoor air samples. The main experimental parameters affecting the extraction efficiency were optimized, including extraction temperature, extraction time, and desorption time. The developed method, which combined the COF-SCU1 coated fiber-based SPME with gas chromatography-mass spectrometric detection, gave large enrichment factors (276–887), low limits of detection (0.03–0.15 ng L−1), and good linearity (0.10–20 ng L−1) for the determination of gaseous benzene homologues from three different indoor air samples. The precision (expressed as the relative standard deviations, RSDs) for six replicate determinations of the analytes at 10 ng L−1 each of the analytes using the same COF-SCU1 coated fiber ranged from 5.8 to 8.9%. The fiber-to-fiber reproducibility for three parallel COF-SCU1 coated fibers varied from 6.9 to 10.7%. The recoveries of the analytes for the method for the spiked indoor air samples with the benzene homologues at the two concentrations of 1 and 10 ng L−1 were in the range of 88.6–101.5% and 87.9–103.4% with the RSDs ranging from 3.9 to 10.3% and 3.4 to 8.5%, respectively.

A solid-phase microextraction fiber was prepared by mixing graphene oxide and hydroxyl-terminated polydimethylsiloxane together and then coating the mixture on the surface of etched stainless-steel wire by sol-gel technology. After aging by heating, the graphene oxide-polydimethylsiloxane composite coated fiber was used for the direct solid phase microextraction of triazole fungicides from water samples. The properties of the graphene oxide-polydimethylsiloxane coating were characterized by transmission electron microscopy and thermogravimetric analysis. And the chemical stability of the coating was tested as well. Several important experimental parameters that could influence the extraction efficiency such as desorption temperature and time, extraction temperature and time, sample pH and stirring rate, were investigated and optimized. Under the optimized conditions, the limits of detection were in the range from 0.01 to 0.03 μg/L. The results indicated that the homemade fiber had the advantages of good thermal and chemical stability and high extraction efficiency, which was successfully applied to the analysis of triazoles in water samples.

In this work, we present a facile and economical approach to synthesize a nanoporous carbon via a KOH chemical activation process using waste pomelo peels as the biomass precursor. The nanoporous carbon derived from pomelo peels exhibits a nanoporous structure (pore size, 0.69 nm) and high surface area (1770 m2 g−1). To evaluate the extraction performance of the nanoporous carbon, it was applied as a solid-phase microextraction coating for the enrichment of benzene homologues from water and soil samples prior to their determination by gas chromatography-mass spectrometry. The main influencing experimental parameters for the extraction were investigated and optimized. Under the optimum conditions, a good linearity for the signal response was achieved in the concentration range of 0.4–100.0 ng L−1 for water samples and 5.0–1000.0 ng kg−1 for soil samples with determination coefficients (r2) larger than 0.9960. The limits of detection (S/N = 3) of the method ranged from 0.05 to 0.18 ng L−1 for water samples and from 0.11 to 0.18 ng kg−1 for soil samples, respectively. The recoveries of the analytes were in the range of 81.3–112.0% with the relative standard deviations (RSDs) ranging from 1.5% to 11.4% (n = 5). The single fiber repeatability and fiber-to-fiber reproducibility values expressed as RSDs were in the range of 2.4–8.1% and 5.9–9.9%, respectively. The method was simple, convenient and feasible for the determination of benzene homologues in real samples.

A new solid-phase microextraction (SPME) fiber coating material, a zeolitic imidazole framework-67 (ZIF-67) templated nanoporous carbon, Co-NPC, was fabricated by one-step direct carbonization of ZIF-67 without using any other carbon precursors. The prepared Co-NPC was then coated onto a functionalized stainless steel wire by a simple physical coating method to prepare SPME fibers. By coupling the Co-NPC coated fiber based SPME with gas chromatography/micro-electron capture detection (GC/μECD), the developed method exhibited low limits of detection (0.07-0.45 ng g(-1)) and a wide linearity (0.30-50 ng g(-1)) for the determination of five organochlorine pesticides (OCPs) in vegetable samples. The method was applied to the analysis of cabbage, cucumber and celery cabbage samples, and the recoveries of the analytes were in the range of 87.9-103.9% with the relative standard deviations (RSDs) ranging from 5.1% to 10.4% (n = 5). Single fiber repeatability and fiber-to-fiber reproducibility values expressed as RSDs were in the range of 4.9-9.6% and 5.8-11.0%, respectively. The method was simple, convenient and feasible for the determination of OCPs in real samples.

Capacitive deionization (CDI) is regarded as a novel, low-cost, and environmentally friendly technique that plays a critical role in desalination and water treatment. Although much progress has been achieved, the development of better CDI technologies, especially through the design and synthesis of various porous carbonaceous materials with enhanced CDI performance, continues to attract increasing interest within the scientific fraternity. Considering that previous traditional porous carbons might suffer from deficient salt adsorption capacity, the nitrogenization of porous carbons, which brings new opportunities for CDI applications, has emerged as an effective strategy to modify the surface characteristics of porous carbons and ultimately improve their CDI performance. This review summarizes the recent significant breakthroughs on the construction of NCs, including in situ doping and post-treatment strategies, and their practices in the field of CDI to impart a comprehensive understanding of the strategic evolution of the synthetic approaches to nitrogen-doped carbons (NCs) with remarkable CDI characteristics. We present an exhaustive analysis of newly synthesized NCs and the impact of their compositional and structural features on their CDI performance; further, we highlight a special emphasis on the possible role of nitrogen dopants in the CDI process. In addition to elucidating the state-of-the-art CDI applications, we address the remaining challenges, and finally, the possible direction for the use of NCs for CDI is described to provide some useful clues for future developments in this promising field.

The design and construction of superior electrocatalysts based on covalent organic frameworks (COFs) for oxygen reduction reaction (ORR) have attracted increasing interest. However, COFs typically exhibit low electrocatalytic activity as a result of their poor electrical conductivity. In this study, a highly graphitic nitrogen-doped porous carbon electrocatalyst (GC@COF-NC) is fabricated by utilizing metal-organic framework (MOF)-derived GC@COF core-shell heterostructure as a sacrificial template. Featured with high conductivity, hierarchical porosity (micropores and mesopores), and abundant N doping, the resulting GC@COF-NC heterostructure manifests a high activity for ORR in an alkaline solution with exceptional onset and half-wave potentials, direct four-electron pathway, and good long-term stability. This synthetic strategy is expected to open a new avenue toward the construction of other COF-derived heteroatom-doped graphitic carbon heterostructures with promising potential for electrocatalytic applications.

The exploration of new-family flexible carbon architectures is significant with regard to flexible electrochemical capacitors. Herein we show the carbonization of core-shell structured metal-organic frameworks (MOFs) (i.e., ZIF-8@ZIF-67) on a waste biomass of cosmetic cotton to prepare flexible nitrogen-doped carbon heteroarchitectures (hetero-fNCs) that possess high supercapacitive properties, including a high energy density of 30 Wh kg−1 at 1440 W kg−1 and good capacitance retention of 89.5% after 5000 cycles. Our elaborately designed hetero-fNCs demonstrate multiple advantages: (i) The outer-layer ZIF-67-derived mesoporous carbons show abundant mesopores, providing abundant ion-diffusion pathways for mass transport and rich graphite microstructures, improving electrical conductivity for electron transfer; (ii) the inter-layer ZIF-8-derived microporous carbons possess a mass of micropores for more charge storage; (iii) the inner-layer cosmetic cotton-derived flexible carbons afford good mechanical flexibility, guaranteeing performance stability during use; and (iv) the plentiful nitrogen dopants within all carbon components increase the capacitance through their pseudocapacitive contribution. As a consequence, the flexible supercapacitor based on hetero-fNCs exhibits high energy and power densities, as well as good bending stability, highlighting the significance of MOFs and flexible biomass materials.

The design of new-family carbon materials to capture more saline ions is one of the biggest challenges of capacitive deionization (CDI) for water desalination. Herein, we demonstrate the preparation of integrated tubular metal-organic framework architectures using a 3D scaffold, and their derivative of nitrogen-doped carbon tubes (denoted as NCTs) that possess a maximum salt adsorption capacity of 56.9 mg g−1 and good cycling stability. Compared with other carbon materials, our elaborately designed NCTs exhibit multiple advantages: (i) tubular architecture diminishes the efficient diffusion distance for both electrons and ions, (ii) binder-free electrode configuration provides increased accessible surface area for ions accommodation, and (iii) plentiful nitrogen dopants improve the reactivity and electrical conductivity of carbon matrix. Consequently, NCTs exhibit an ultrahigh CDI performance compared to other carbon materials reported previously, highlighting the significance of 3D free-standing carbon architectures for CDI application.

Featuring favorable ion transfer and high thermal stability, NASICON-structured Na3V2(PO4)3 has been regarded as a promising cathode candidate for sodium-ion batteries. However, this material might be impeded by inferior rate capability owing to its disappointing electron conductivity. To address this issue, a combined technique of carbon coating and Nb5+ doping was carried out for the first time. On one hand, the coated carbon nano-shell could construct an electron-conductive network and buffer the volume stain. On the other hand, the introduction of Nb5+ into the Na3V2(PO4)3 crystal could regulate the relevant crystal parameters and create more vacancies, further facilitating the transfer of sodium ions. As a result, the optimized Nb-doped Na3V2(PO4)3@C material achieved an excellent performance of 81.6 mA h g−1 at 50C and a high-capacity retention ratio of 80.8% even after 1600 cycles. This work not only highlights the significance of carbon coating and Nb5+ doping, but also shows promising opportunities in potential cathode alternatives for sodium-ion batteries.

A nitrogen-doped metal organic framework (MOF) based porous carbon (C-(C3N4@MOF)) was produced by the carbonization of a graphitic carbon nitride (g-C3N4) templated MOF (NH2-MIL-125). The C-(C3N4@MOF) was then coated on a stainless steel wire by sol-gel technique to serve as a solid-phase microextraction (SPME) fiber coating. The coated fiber was studied for the extraction of fourteen organophosphorous pesticides (OPPs) from different fruit and vegetable samples followed by gas chromatography-mass spectrometer (GC–MS) detection. The C-(C3N4@MOF) coated fiber exhibited a high extraction capability for the OPPs. Both single factor optimization and response surface analysis (Box-Behnken Design) methods were implemented to optimize the experiment conditions for the extraction. The results indicated that the linear response for the fourteen OPPs was in the range from 0.69 to 3000 ng g−1 and the coefficients of determination (r2) ranged from 0.9981 to 0.9998. The limits of detection (LODs, S/N = 3) ranged from 0.23 to 7.5 ng g-1. The method recoveries (R) of the fourteen OPPs for spiked fruit and vegetable samples were between 82.6% and 118%, with the relative standard deviations (RSDs) varying from 2.8% to 11.7%. The fiber can be reused over 100 times without a significant loss of extraction efficiency.

A novel solid phase microextraction fiber was prepared for the first time by using a sol-gel technique with hydroxypropyl-β-cyclodextrin-functionalized reduced graphene oxide as the fiber coating material. The results verified that the β-cyclodextrin was successfully grafted onto the surface of reduced graphene oxide and the coating possessed a uniform folded and wrinkled structure. The performance of the solid phase microextraction fiber was evaluated by using it to extract nine volatile aromatic compounds from water samples before determination with gas chromatography and flame ionization detection. Some important experimental parameters that could affect the extraction efficiency such as the extraction time, extraction temperature, desorption temperature, desorption time, the volume of water sample solution, stirring rate, as well as ionic strength were optimized. The new method was validated to be effective for the trace analysis of some volatile aromatic compounds, with the limits of detection ranging from 2.0 to 8.0 ng/L. Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 2.5-9.4 and 5.4-12.9%, respectively. The developed method was successfully applied to the analysis of three different water samples, and the recoveries of the method were in the range from 77.9 to 113.6% at spiking levels of 10, 100, and 1000 ng/L, respectively.

In this study, an ordered mesoporous carbon (OMC) with a large surface area, uniform mesoporous structure and large pore volume was synthesized by using Zeolite Socony Mobil-5 (ZSM-5) as the hard template and sucrose as the carbon precursor. The synthesized OMC-ZSM-5 was immobilized onto a stainless steel wire for the preparation of SPME fibers by a sol–gel coating method. The SPME of polycyclic aromatic hydrocarbons (PAHs) with the OMC-ZSM-5 coated fiber coupled with gas chromatography/flame ionization detection (GC/FID) provided large enhancement factors (738–2359), low limits of detection (LODs, 0.5–1.6 ng g−1) and good linearities (1.7–100.0 ng g−1) for soil samples. The relative standard deviations (RSDs) for single fiber and fiber-to-fiber reproducibilities were in the range of 4.6–7.9% and 6.1–10.2%, respectively. The developed method was successfully applied to the analysis of soil samples and the recoveries of the analytes for the method were in the range from 88.0% to 103.8%. The OMC-ZSM-5 coated fiber was stable enough for 160 extractions without a significant loss of extraction efficiency.

A novel three-dimensional graphene (3D-G) coated fiber for solid-phase microextraction (SPME) was fabricated via a sol–gel coating method on stainless steel wires. The 3D-G was obtained by connecting graphene oxide (GO) sheets with Ca2+ and water molecules by hydrothermal treatment. Due to the π–π stacking and hydrophobic interactions between the 3D-G and the analytes, the 3D-G fibers showed high extraction efficiencies for the polycyclic aromatic hydrocarbons (PAHs). The developed method, which combined the 3D-G coated fiber-based SPME with gas chromatography-flame ionization detection, had large enhancement factors (842–2458), low limits of detection (2.0–10.0 ng L−1) and good linear range (10.0–1000.0 ng L−1) for the PAHs in water samples. Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 4.7–8.8% and 6.4–11.9%, respectively. The recoveries of the analytes for the method were in the range from 76.5% to 102.6%. The fiber exhibited an excellent durability and can be reused more than 150 times without a significant loss of the extraction performance. The method was successfully applied to the determination of PAHs in water and soil samples.

As a category of long-term protective coating, phenol formaldehyde (PF) has been extensively applied in the nuclear industry. However, PF might emerge adverse degradation processes under the γ ray irradiation environment, which greatly restricts its further applications as the highly-efficient protective coatings. For the sake of addressing this issue, herein, a novel phenol noncovalent modified graphene oxide/phenol formaldehyde nanocomposite (GPF) has been constructed via in situ guiding phenol formaldehyde micromolecules format on the well-dispersed graphene oxide surface. Electron spin resonance and electrochemical tests intensively demonstrate that the highly dispersed graphene could act as an enhanced radical scavenger and retain the corrosion resistance properties for the GPF composites under the gamma irradiation environment.

2D transition metal dichalcogenides (TMDs) have received widespread interest by virtue of their excellent electrical, optical, and electrochemical characteristics. Recent studies on TMDs have revealed their versatile utilization as electrocatalysts, supercapacitors, battery materials, and sensors, etc. In this study, MoS2 nanosheets are successfully assembled on the porous VS2 (P-VS2) scaffold to form a MoS2/VS2 heterostructure. Their gas-sensing features, such as sensitivity and selectivity, are investigated by using a quartz crystal microbalance (QCM) technique. The QCM results and density functional theory (DFT) calculations reveal the impressive affinity of the MoS2/VS2 heterostructure sensor toward ammonia with a higher adsorption uptake than the pristine MoS2 or P-VS2 sensor. Furthermore, the adsorption kinetics of the MoS2/VS2 heterostructure sensor toward ammonia follow the pseudo-first-order kinetics model. The excellent sensing features of the MoS2/VS2 heterostructure render it attractive for high-performance ammonia sensors in diverse applications.

Mass interfacial processes have been considered as one of the crucial factors supporting fundamental research. Due to the low cost and conceptual simplicity, significant advancements have been achieved in the development of methodologies based on piezoelectric devices for in situ determination of mass changes on the surfaces of deposited materials under various conditions. The introduction of nanomaterials for designing sensors and monitoring systems becomes essential to create advanced detection systems for selective sensing of toxic analytes for environmental remediation. The integration of materials with predesignated nanostructures into sensor devices, such as surface acoustic wave (SAW), quartz crystal microbalance (QCM), and QCM with dissipation (QCM-D) monitoring, has led to an immense progress in the sensing applications of toxic target analytes at the nanogram range. Here, an overview is introduced of recent advancement in the fabrication of piezoelectric devices for the interfacial mass sensing of targeted chemical vapors and ions through combination with nanoporous materials including mesoporous materials carbon-based nanomaterials, metal–organic frameworks (MOFs), MOF-derived nanoporous carbons, Prussian blue (PB) and its analogues (PBA), zeolites and related materials. Challenges and future prospect are also summarized by the advanced QCM technique associated with properties of nanostructured materials.

A hybrid material of the zinc-based metal-organic framework-5 and graphene oxide (metal-organic framework-5/graphene oxide) was prepared as a novel fiber coating material for solid-phase microextraction (SPME). The SPME fibers were fabricated by covalent bonding via chemical cross-linking between the coating material metal-organic framework-5/graphene oxide and stainless steel wire. The prepared fiber was used for the extraction of five triazole fungicides from fruit and vegetable samples. Gas chromatography coupled with microelectron capture detector (GC-μECD) was used for quantification. The developed method gave a low limit of detection (0.05-1.58 ng g(-1)) and good linearity (0.17-100 ng g(-1)) for the determination of the triazole fungicides in fruit and vegetable samples. The relative standard deviations (RSDs) for five replicate extractions of the triazole fungicides ranged from 3.7 to 8.9%. The method recoveries for spiked fungicides (5, 20, and 50 ng g(-1)) in grape, apple, cucumber, celery cabbage, pear, cabbage, and tomato samples were in the range of 85.6-105.8% with the RSDs ranging from 3.6 to 11.4%, respectively, depending on both the analytes and samples. The metal-organic framework-5/graphene oxide coated fiber was stable enough for 120 extraction cycles without a significant loss of extraction efficiency. The method was suitable for the determination of triazole fungicides in fruit and vegetable samples.

Porous organic frameworks (POFs), a general term for covalent‐organic frameworks (COFs), covalent triazine frameworks (CTFs), porous aromatic frameworks (PAFs), etc., are constructed from organic building monomers with strong covalent bonds and have generated great interest among researchers. The remarkable features, such as large surface areas, permanent porosity, high thermal and chemical stability, and convenient functionalization, promote the great potential of POFs in diverse applications. A critical overview of the important development in the design and synthesis of COFs, CTFs, and PAFs is provided and their state‐of‐the‐art applications in analytical chemistry are discussed. POFs and their functional composites have been explored as advanced materials in “turn‐off” or “turn‐on” fluorescence detection and novel stationary phases for chromatographic separation, as well as a promising adsorbent for sample preparation methods. In addition, the prospects for the synthesis and utilization of POFs in analytical chemistry are also presented. These prospects can offer an outlook and reference for further study of the applications of POFs.