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The bimetallic metal-organic frameworks (MOFs) with free carboxyl groups and bimetallic centers (expressed as MIL-53(Fe, Al)-COOH) are successfully synthesized by a simple one-step method. The preparation conditions and adsorption properties of the materials are studied. The introduction of trimellitic acid effectively enhances the hydrophilicity of the resultant MOFs and the obtained MIL-53(Fe, Al)-COOH shows better adsorption performance than corresponding monoligand and monometallic center MOFs. The results show hydrogen bond interaction between free carboxyl groups of MOFs and amino and carboxyl groups of glutathione(GSH) is the predominant driving force for GSH adsorption. The enrichment results demonstrate that the prepared MIL-53 (Fe, Al) -COOH has the ability to enrich GSH from aqueous solution up to 221.46 mg g−1, which indicates that MIL-53 (Fe, Al)-COOH could be used as a promising potential adsorbent to enrich GSH from aqueous solution. [ABSTRACT FROM AUTHOR]

The misuse of antibiotics, such as tetracycline (TC), can seriously harm human health so it is of great practical importance to sensitively and rapidly detect TC. In this paper, an Eu3+-functionalized Zr-MOF (Eu3+@UiO-66-(OH) 2) was successfully prepared by a post-synthetic modification strategy as a ratiometric fluorescent sensor for ultrasensitive and specific detection of TC in aqueous medium. The proposed Eu3+@UiO-66-(OH) 2 sensor possessed remarkable fluorescence enhancement properties besides high specific surface area and excellent stability. In the quantitative analysis of TC, the sensor exhibited fast response (<60 s), wide linear range (0–160 μM), high sensitivity (detection limit as low as 1.33 nM) and high selectivity for TC. Furthermore, it has been successfully utilized in determination of TC in real samples, demonstrating its application potential in complex environmental water system. [Display omitted] • Eu3+@UiO-66-(OH) 2 was prepared by a post-synthetic modification strategy for tetracycline detection. • The fluorescence sensor with self-calibration function realizes the color change from green to red for easy visual detection. • The sensor has a low detection limit, high selectivity and strong anti-interference ability. [ABSTRACT FROM AUTHOR]

The detection of acetaminophen (ACOP) and its toxic hydrolyzed product p-aminophenol (4-AP) is very significant for clinical diagnosis and quality control of drug formulation. In this study, a novel electrochemical sensor based on MoS 2 embedding triangular Ag nanoplates (Tri-AgNPs) coated MOF-808 was developed for simultaneous and sensitive detection of ACOP and 4-AP. The morphology and structure MOF-808@MoS 2 /Tri-AgNPs nanocomposite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and so on. The electrochemical and electrocatalytic properties of the composite electrode were evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results demonstrated that the constructed sensor had excellent electrochemical performance for ACOP and 4-AP detection due to the synergistic interaction among MOF-808, MoS 2 and Tri-AgNPs. The proposed sensor exhibited a wide linear range (1–450 μM) and low limits of detection for detection of ACOP (0.054 μM) and 4-AP (0.046 μM). At the same time, the sensor also showed outstanding repeatability, reproducibility, stability and selectivity. In addition, MOF-808@MoS 2 /Tri-AgNPs/GCE was also employed to determine ACOP and 4-AP in acetaminophen tablets and Yellow River water samples with satisfactory recovery rates, which indicated the feasibility of the developed electrochemical sensor in the actual sample analysis. [Display omitted] • MOF-808 coating by conductive MoS 2 improves the conductivity of MOF-808 composite. • Tri-AgNPs embedding in MoS 2 disperses MoS 2 and AgNPs and enhances active sites. • Synergy of MoS 2 , Tri-AgNPs and MOF-808 ensures high detection sensitivity of ACOP and 4-AP. [ABSTRACT FROM AUTHOR]

Uric acid and dopamine are closely related to the health of the organism, so it is important to determine them simultaneously and efficiently. In this paper, the metal-organic framework DUT-67 was in situ grown on the surface of bimetallic oxide ZnCo 2 O 4 nanoflowers, and then ultrasonically compounded with multi-walled carbon nanotubes (MWCNTs) to prepare DUT-67/ZnCo 2 O 4 -MWCNTs composite. The prepared composite was characterized by XRD, SEM, XPS, FTIR, BET and other techniques. Finally, an electrochemical sensor based on DUT-67/ZnCo 2 O 4 -MWCNTs composite modified glassy carbon electrode for simultaneous detection of dopamine (DA) and uric acid (UA) was fabricated. The introduction of ZnCo 2 O 4 into the composite efficiently overcame the disadvantage of the easy aggregation of DUT-67 and produced a synergistic effect with MWCNTs. The electron transfer rate between the electrode and the electrolyte solution was accelerated, and the detection signals of the target molecules were amplified. After characterizing the electrochemical properties of the composite electrode, it was found that the constructed electrochemical sensor showed low detection limits for DA and UA, which were 12 nM and 8.7 nM, respectively, and the wide linear range of 1.0–180.0 μM. Besides, the sensor had excellent reproducibility, repeatability, anti-interference and stability. The proposed sensor was also successfully used to determine the contents of DA and UA in dopamine injection and urine samples with relatively satisfactory recovery rates. This work not only provides a new strategy for the preparation of MOF modified electrodes, but also has a potential application prospect in bioassays. [Display omitted] • DUT-67 aggregation was eliminated and SSA was enhanced by introducing ZnCo 2 O 4 nanoflower. • Synergistic effect of MWCNTs and DUT-67/ZnCo 2 O 4 improves the electrochemical performance. • DUT-67/ZnCo 2 O 4 -MWCNTs/GCE realizes simultaneous detection of DA and UA with high sensitivity. • This work provides a new strategy for preparation of MOFs based electrochemical sensor. [ABSTRACT FROM AUTHOR]

A novel dual-emission ratiometric fluorescent sensor Eu3+/CDs@UiO-66 was synthesized by post-synthesis modifying of UiO-66, a zirconium-based MOF formed by 1,4-phthalic acid (PTA) and Zr4+ , with europium ion (Eu3+) and carbon dots (CDs) and utilized for the determination of Cu2+ ions. The prepared composites not only maintain the excellent optical properties of CDs and Eu3+ but also have good stability in an aqueous solution. At the excitation wavelength of 299 nm, Eu3+/CDs@UiO-66 has two distinct emission peaks at 394 nm and 615 nm, respectively. More interestingly, when the material was dispersed in an aqueous solution containing Cu2+ ions, the characteristic peak of Eu3+ at 615 nm decreased significantly, while the characteristic peak of CDs at 394 nm remained unchanged. In the range of 0–500 μM, the relative fluorescence intensity ratio (F 394 /F 615) linearly increased with increasing Cu2+ ion concentration, and the detection limit was calculated to be 51 nM (3S b /K sv). At the same time, the material can also be effectively applied to the detection of Cu2+ in environmental water samples. So Eu3+/CDs@UiO-66 can be developed as a potential ratiometric fluorescent sensor to detect Cu2+ ions. [Display omitted] • A novel dual-emission ratiometric fluorescent sensor is fabricated for Cu2+ sensing • CDs is prepared with environmentally friendly Pinellia pinellia as raw material. • This method is beneficial for copper visual analysis. [ABSTRACT FROM AUTHOR]

Novel pompon-like nickel-cobalt double hydroxide/graphene oxide (Ni(OH) 2 /Co(OH) 2 /GO) composites were successfully synthesized via a simple one-step solvothermal process. Their structure, morphology, surface and electrochemical properties were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge(GCD) curves. The composite electrodes showed typical pseudocapacitance performances. When addition amount of graphene oxide was 10mg, resulted composite exhibited a high specific capacitance (2050.6 F g −1 at 1 A g −1 ) and good cycling stability with a capacitance retention of 84% after 1000 cycles. Appropriate amount of graphene oxide not only served as a structural director but also enhanced the conductivity and stability of the resulted composite. The attractive performances and facile fabrication made the prepared Ni(OH) 2 /Co(OH) 2 /GO composite become a promising candidate for low-cost high-performance energy storage device. [ABSTRACT FROM AUTHOR]

A series of porous materials with good mechanical and fluorescence properties enhanced by graphene quantum dots (GQDs) were prepared using surfactant reverse micelle swelling method with acrylamide (AAM) and 1-vinylimidazole (VIM) as monomers, ethylene glycol dimethacrylate (EGDMA) as crosslinking agent and azobisisobutyronitrile(AIBN) as initiator. Effects of additional amount of GQDs on the pore structure, fluorescence property, zeta potential and mechanical properties of the porous materials were systematically investigated. The surface area and pore volume increased as introduction of GQDs, while average pore width increased at first and then decreased with the amount of GQDs increasing, verifying the successful preparation of the porous materials. The fluorescence intensity changed to certain degree by the introduction of GQDs, which might resulted from photoelectron transfer between the GQDs and polymer matrices. The mechanical strength of the porous materials was greatly enhanced with introduction of GQDs due to the increase in storage modulus and permeability. The present work will shed light on the preparation of porous materials with high mechanical strength and fluorescence. [ABSTRACT FROM AUTHOR]

Bimetallic metal-organic frameworks (MOFs) with a controlled morphology are potential materials for boosting the electrochemical performance of supercapacitors owing to their unique structural merits. Herein, a solvent-regulated strategy was proposed to synthesize bimetallic MOFs with various morphologies, such as microflowers, microspheres, and nanosheets, and the possible mechanisms of morphology control during nucleation and crystal growth were analyzed. When employed as electrode materials for supercapacitors, the NiCo-MOF microflowers possessed the biggest specific capacitance, which could achieve 1086 F g−1 at a current density of 1 A g−1. To further improve the electrochemical performance of materials, NiCo-P was prepared via a low-temperature phosphating method using NiCo-MOF microflowers as the precursor. Electrochemical studies displayed that the NiCo-P(6) microflowers exhibited good capacitance and superior rate capability with specific capacitances of 1592 and 1384 F g−1 at 1 and 20 A g−1, respectively. Furthermore, an asymmetric supercapacitor assembled by NiCo-P(6) and active carbon exhibited a high energy density of 51.2 Wh kg−1 at a power density of 749.8 W kg−1 and outstanding cycling stability. This work is easy to operate and can be extended to the preparation of other MOF-based electrode materials. The delivered excellent electrochemical performance suggests the resulted flower-like NiCo-P is a promising electrode material for advanced energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the flexibility, ductility and tensile properties, hydrogel is considered as promising candidates for the new generation of wearable flexible devices. However, it is still a challenge to endow multiple functions such as excellent conductivity, high stretchability, self-healing, self-adhesion, and biocompatibility in one hydrogel network. Herein, a two-step method was used to prepare multifunctional transparent tannic acid/sodium alginate/polyacrylic acid/carboxymethyl cellulose/aluminum trichloride (SA/TA/PAA/CMC/Al(III)) hydrogels with high stretchability, toughness, adhesion, and conductivity. This hydrogel can adhere to various substrates both organic and inorganic materials. The highest adhesion strength of the hydrogels to the iron sheet reaches 22.33 kPa with the fracture stress being 0.16 MPa and the toughness 1.01 MJ/m3. Moreover, the hydrogel exhibited repeatable and durable adhesion to human skin and could be peeled off completely without any residual, irritation or allergic reactions. Additionally, the hydrogels also have good repetitive adhesion and strain sensitivity. It was demonstrated that both large-scale and small-scale movements of the human body could be monitored by directly attached to various parts of the human body by the self-adhesion. This work provides a new prospect for the design of the biocompatible hydrogels with transparent, stretchable, self-adhesive, and strain-sensitive properties for potential applications in wearable electronic sensors. [Display omitted] [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have received tremendous interest due to their structural diversity and versatility. These unique physicochemical properties make them exhibit great application potential in the field of electrochemical sensor. In this study, an imine bond-linked COF with porosity and large specific surface area was fabricated by a dehydration condensation reaction between 1, 3, 5-tris(4-formylphenyl)benzene (TFPB) and 1, 3, 5-tris(4-aminophenyl) benzene (TAPB) and combined with high electrical conductivity of oxidized multi-walled carbon nanotube (Ox-MWCNT). The structure of the COF and the resulted composite material were confirmed through a series of characterization techniques, including Fourier-transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy and thermogravimetric analysis, then a co-modified glassy carbon electrode was constructed for simple, sensitive and selective electrochemical recognition of dopamine (DA) and uric acid (UA). The fabricated electrochemical sensor displayed a strong current response to both DA and UA in the phosphate buffer solution (PBS) at pH = 6.5. The synergistic effect between COFs and Ox-MWCNT effectively improved the analytical sensitivity for the target analytes. Under optimized experimental conditions, the method showed good performance for DA and UA in the concentration range of 0.6–250.0 μM with low detection limits of 0.073 μM and 0.063 μM (S/N = 3), respectively. Moreover, the proposed sensor exhibited high selectivity, longtime stability, desirable repeatability and acceptable reproducibility and can be used to analyze simultaneously DA and UA in biological and medicine samples with satisfactory results. Our work not only provides a simple way to detect DA and UA quantitatively in real samples, but also offers a new platform for COF-based composite application in electrochemical sensing. [Display omitted] • TFPB-TAPB-COF is prepared via a simple solvothermal method. • TFPB-TAPB-COF/Ox-MWCNT/GCE is fabricated for sensing of dopamine (DA) and uric acid (UA). • The sensor has low detection limits and wide linear ranges for detection DA and UA. • The sensor is successfully applied to the determination of DA and UA in real samples. [ABSTRACT FROM AUTHOR]

As a typical pseudocapacitance material, NiS is considered a promising electrode material due to its high theoretical specific capacitance and abundant reserves. However, the electrical conductivity is poor, resulting in a decrease in cycle stability and rate performance. Here, we introduce cobalt-containing porous nanocarbon (Co-NC) derived from zeolite-imidazolate frameworks (ZIFs) as a supporting base to design a hybrid structure. As an electrode material, NiS@Co-NC nanocomposite has a composite effect of double-layer capacitive porous carbon and pseudo-capacitance NiS nanoparticles and excellent electrochemical performance. Specifically, the specific capacitance of NiS@Co-NC nanocomposite is as high as 1116.6 F·g−1 when the current density is 1 A·g−1, and capacity retention is 90.177% at a very high current density of 10 A·g−1 after 5000 cycles. Moreover, the fabricated hybrid supercapacitor delivers an energy density of 21.6 Wh·kg−1 at 799.9 W·kg−1 with coulombic efficiency of 90.177%, and 14.22 Wh·kg−1 at a high power density of 7999.9 W·kg−1, along with excellent cyclic stability of 89.85% at 5 A·g−1 after 5000 cycles. All results indicate that NiS@Co-NC nanocomposites have the potential to be applied as electrodes in hybrid supercapacitors and other energy storage devices. ZIF-67 @ZIF-8 was synthesized through hydrothermal reaction and carbonized as a sacrificial template to generate cobalt-containing nano-carbon and carbon nanotubes. [Display omitted] • CNTs interconnected NiS@Co-containing porous carbon nanocomposite was synthesized. • The composite showed a strong synergistic effect of NiS, CNTs and metallic cobalt modified porous carbon. • NiS@Co-NC nanocomposite has a high specific capacitance of 1116.6 F.g-1 1 A.g-1. [ABSTRACT FROM AUTHOR]

Herein, covalent organic framework (COF) and covalent triazine framework (CTF) have been successfully combined for electrochemical sensing via carboxylated multi-walled carbon nanotubes (COOH-MWCNTs). The COF was synthesized from 1,3,5-tris-(4-formylphenyl) benzene (TFPB) and benzidine (BD), named TFPB-BD-COF. Meanwhile, CTF was synthesized by 1, 4-dicyanobenzene (DCB), then chemically activated with KOH at 700 °C to obtained chemically activated porous product, caCTF-1–700. A novel electrochemical sensor based on TFPB-BD-COF/caCTF-1–700/COOH-MWCNT composite was constructed for simultaneous detection of acetaminophen (ACOP) and 4-aminophenol (4-AP). The electrochemical behaviors of the ACOP and 4-AP on the TFPB-BD-COF/caCTF-1–700/COOH-MWCNT electrode were explored via differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The fabricated TFPB-BD-COF/caCTF-1–700/COOH-MWCNT composite modified glassy carbon electrode (GCE) possessed outstanding electrocatalytic performance for the electro-oxidation of acetaminophen (ACOP) and 4- aminophenol (4-AP). Under optimal conditions, the linear ranges were 0.6–150 μM for ACOP and 4-AP, respectively, with the low detection limits of 0.053 μM and 0.075 μM, respectively. In addition, it also showed excellent selectivity, repeatability, reproducibility and stability. The proposed modified electrode was applied for the determination of ACOP and 4-AP in acetaminophen tablet and Yellow river water and obtained satisfactory recovery between 96.31~103.96% and 97.2~101.6%, respectively. [Display omitted] • Imine COF and triazine CTF are combined for electrochemical sensing for the first time. • Hierarchical porous composite provides large surface area for improved sensitivity. • COOH-MWCNT connecting two COFs improved electrocatalytic activity and conductivity. • The sensor shows high sensitivity for simultaneous determination of ACOP and 4-AP. [ABSTRACT FROM AUTHOR]

Due to the insufficient performance, it is still a challenge to combine conventionally synthesized metal-organic framework (MOF-74) with other materials to fabricate composite electrodes for high-performance supercapacitors. Herein, we synthesized a series of NiCo-MOF-74 composite materials with different amounts of polypyrrole nanotubes (T-PPy) denoted as NiCo-MOF-74/T-PPy-m (m = 2.5, 5, 10, 15 and 20) through in situ growth of the bimetallic MOF around the PPy nanotubes by a simple solvothermal method. By comparison, the NiCo-MOF-74(1)/T-PPy-10 composite, with a Ni/Co molar ratio of 1:1 obtained in the presence of 10 mg of T-PPy, possessed the highest specific capacitance of 849 C·g−1 at 1 A·g−1 and excellent cyclic stability with a capacitance retention rate of 90.0% after 10,000 cycles as well as good rate performance. Moreover, the assembled asymmetric supercapacitor respectively using NiCo-MOF-74(1)/T-PPy-10 and active carbon as positive electrode and negative electrode achieved a superior energy density of 58.4 Wh kg−1 at the power density of 747.6 W kg−1 and high cyclic lifespan (91.4% capacitance retention after 10,000 cycles). The mechanism of capacitance increase was studied in detail, influences of metal molar ratios, morphology and addition amounts of PPy on electrochemical performances of the formed composition materials were systematically discussed, and it was found that the interpenetrating network structure assembled by "string of candied haws"-like T-PPy-interweaved NiCo-MOF-74(1) polyhedrons possessed the best capacitive performance for enhanced conductivity of the resulted composite, improved dispersity of the bimetallic MOF and more exposed active sites. And the interwoven structure alleviated the stress change-induced structure or phase variation caused by repeated volumetric swelling and shrinking during charge/discharge cycle and enhanced the rate capability and cycling stability. Interpenetrating network structure assembled by "string of candied haws"-like T-PPY-interweaved NiCo-MOF-74(1) polyhedrons [Display omitted] • Interpenetrating networks assembled by PPY nanotube-interweaved NiCo-MOF-74 were constructed. • The structure delivered good conductivity, high specific capactitance and long cyclic lifespan as supercapacitor electrode. • NiCo-MOF-74 in situ grown around the PPY tubes was directly used as electrode without carbonization and heteroatom doping. [ABSTRACT FROM AUTHOR]

Catechol (CC) and hydroquinone (HQ) are highly toxic organic phenolic compounds and they possess immeasurable harm to human health and the environment. Their simultaneous detection can provide valuable reference for the environment protection and human health. In this work, an imine bond-linked covalent organic framework (COF) was fabricated via a facile solvothermal method and then cooperated with multi-walled carbon nanotubes (MWCNTs) to construct a novel electrochemical sensor. The petal-shaped COF provides large specific surface area, and MWCNTs remarkably improve the conductivity of the resulted modified electrode. Co-modification of the COF and MWCNTs to glassy carbon electrode (GCE) leads to a three-dimensional structure and significant synergy. Under the optimal experimental conditions, good linear relationships are obtained over the concentration range from 4.0 to 450 μM for simultaneous determination of CC and HQ and the detection limits are 0.36 μM and 0.38 μM, respectively. The proposed electrochemical sensor shows excellent repeatability, reproducibility, stability, anti-interference and can be exploited to detect simultaneously CC and HQ in Yellow River water and tap water samples. [Display omitted] • TFPPy-BD-COF/MWCNT/GCE shows high electrocatalytic ability catechol(CC) and hydroquinone(HQ). • The prepared electrochemical sensor has low detection limit and wide linear range for detection CC and HQ. • The sensor has been successfully applied to the determination of catechol and hydroquinone in real water samples. [ABSTRACT FROM AUTHOR]

In this present work, a COF based electrochemical sensor is successfully fabricated by employing TFPB-BD-COF prepared through condensation reaction of 1, 3, 5-tris-(4-formylphenyl) benzene (TFPB) and benzidine (BD), in-situ reduced platinum nanoparticles (PtNPs) and amino functionalized multi-walled carbon nanotubes (NH 2 -MWCNTs) as modified materials for sensitive electrochemical determination of catechol (CC), hydroquinone (HQ) and resorcinol (RS) simultaneously. The obtained TFPB-BD-COF/PtNPs/NH 2 -MWCNTs/GCE exhibits superior electrochemical performance compared with those modified by individual components. The oxidation peaks of CC, HQ and RS show good linear response in the concentration ranges of 0.2–360 μM, 0.2–360 μM and 4–360 μM, respectively. The corresponding limits of detection (LODs) of CC, HQ and RS were 0.015 μM, 0.022 μM and 0.26 μM (S/N = 3). In addition, it possesses outstanding selectivity, repeatability, reproducibility and stability. The proposed modified electrode has been successfully applied for the determination of HQ, CC and RS in tap water, Yellow River water and domestic wastewater with satisfactory. [Display omitted] [ABSTRACT FROM AUTHOR]

In this present paper, a novel electrochemical sensor based on a covalent organic framework (COF) and lanthanum oxide (La 2 O 3) and multi-wall carbon nanotubes (MWCNT S) was prepared for sensitive and selective detection of dopamine (DA) and uric acid (UA). The sensor demonstrated excellent analytical performance for DA and UA owing to the synergistic effect among large surface area of COF, highly conducting MWCNTs and highly catalytic La 2 O 3. Particularly, the COF with a BET surface area of 1396.04 m2/g prepared by the Schiff base reaction between 2, 5-dibromobenzene-1, 4-dicarbaldehyde (DBTA) and 2, 4, 6-tris(4-aminophenyl)− 1, 3, 5-triazine (TAPT), significantly enhanced the adsorption and enrichment ability of the resulted modified electrode toward the target molecules. The constructed electrochemical sensor possessed low detection limits (0.039 μM for DA and 0.024 μM for UA) and wide linear ranges (2 ~ 450 μM for DA and 0.4 ~ 450 μM for UA) and could be employed to detect simultaneously the contents of DA and UA in biological and medicine samples with outstanding reproducibility, high stability as well as strong anti-interference property. [Display omitted] [ABSTRACT FROM AUTHOR]

A blue fluorescent Si/CDs is successfully synthesized via a conventional solvothermal method, which can serve as a sensitive fluorescent sensor to detect Hg2+ ions in water. The synthesized Si/CDs material exhibits excellent optical properties, high chemical and structural stability in an aqueous solution. Under natural light, the mixture is a colorless suspension while under ultraviolet light, it can emit bright blue fluorescence and the maximum excitation and emission wavelengths are 377 and 464 nm, respectively. Particularly, Hg2+ can lead to nearly complete fluorescence quenching of the material suspension and the emission intensity of the constructed fluorescent sensing system linearly decreases with increasing Hg2+ concentration in the range of 0–200 μM with a detection limit of 26.7 nM (S/N = 3). The proposed method has been successfully applied in detection of Hg2+ content in environmental and drinking water samples. In addition, the test paper strips based on fluorescent Si/CDs are also prepared by an immersion method for rapid and quantitative detection of Hg2+ in water environment through a visual mode. [Display omitted] • Blue fluorescence Si/CDs was synthesized and employed as a sensing material for sensitive detection of Hg2+. • A turn-off fluorescent sensor based on Si/CDs had a wide linear range (0-200μM) and low LOD (26.7 nM) for Hg2+. • Si/CDs based fluorescent test paper could quantify Hg2+ rapidly and conveniently in environmental water samples. [ABSTRACT FROM AUTHOR]

In this work, a novel triazine-based covalent organic framework (TS-COF) was constructed by the condensation of 1, 3, 5-tris-(4-aminophenyl)triazine (TAPT) and squaric acid (SA) under solvothermal condition. By in situ growth of Au nanoparticles (AuNPs) on the surface of TS-COF, the AuNPs@TS-COF composite with enhanced electroactivity was prepared successfully. After introduction of reduced graphene oxide (RGO), the constructed AuNPs@TS-COF/RGO nanocomposite modified electrode exhibited excellent conductivity and outstanding catalytic activity, and could be employed to determine uric acid (UA), dopamine (DA) and ascorbic acid (AA) in urine sample simultaneously, accurately and rapidly with high sensitivity, good selectivity and high stability. The detection limits of UA, DA and AA were 0.07 μM, 0.03 μM and 4.30 μM (S/N = 3), respectively. [Display omitted] • A novel triazine-based covalent organic frameworks (TS-COF) was designed and synthesized. • The work employing AuNPs@TS-COF/RGO to build a sensor was first reported. • The sensor displayed high sensitivity and wide linear range for the simultaneous determination of UA, DA and AA. • The work paved the way to utilize triazine-based COFs to design electrochemical sensors. [ABSTRACT FROM AUTHOR]

As a new kind of porous organic material, covalent organic framework materials (COFs) have many advantages and have been widely used in catalysis, sensing, drug delivery, gas separation and other fields. In this paper, A COF was successfully prepared based on Schiff base reaction of 1, 3, 6, 8-tetrakis(4-formyl phenyl) pyrene (TFPPy) and 1, 3, 6, 8-tetrakis(4-amino phenyl) pyrene (PyTTA) named as TF-Py COF, and its structure was characterized in detail. By physically combining a pre-prepared three-dimensional carbon material containing nitrogen (3D NCNF-T) and TF-Py COF, followed by deposition of AuNPs, relatively poor conductivity of TF-Py COF was efficiently overcome and a novel electrochemical sensing platform with high sensitivity and high selectivity for simultaneous detection of acetaminophen (ACOP) and 4-aminophenol (4-AP) was successfully constructed. The synergistic effect between TF-Py COF, 3D NCNF-T and AuNPs effectively improves the analytical sensitivity of target analytes. Under optimized experimental conditions, the electrochemical sensing platform has a sensitive volt-ampere response and a wide linear range to both ACOP and 4-AP, and the detection limits are 0.13 μM and 0.05 μM (S/N = 3), respectively. The sensor has been successfully applied to the determination of ACOP and 4-AP in acetaminophen tablets and Yellow River water samples, with high recovery rate, good selectivity and reproducibility, and strong anti-interference ability. It is expected to be widely used in the actual sample detection. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, novel hybrid nanomaterials constituting carbonized biomass materials derived from walnut shells and metal-organic framework (MOF) have been researched as a new class of renewable supercapacitor materials for electrochemical energy storage. One synthetic route is employed to grow Ni-MOF in the peripheries and channels of walnut shells derived carbon (WS), which had been carbonized previously by heat treatment in air at 850 °C to produce a highly porous network, and vulcanized polyaniline (SPANI) is used as a dummy plate preventing the agglomeration of MOFs and a wire connecting WS and MOFs, which easily improves the electron transfer and enhances the conductivity of the electrode material. The specific capacitance of the obtained WS@Ni-MOF composite is up to 4 times that of the biochar at the current density of 1 A g-1. The connection of SPANI also obviously accelerates the transfer of electrolyte ions. The resulting specific capacitance could reach 14 times of the biochar and exhibit high cycle stability (retention rate of 90.4% after 20000 cycles). In addition, the assembled asymmetrical supercapacitor (ASC) shows a high energy density of 34.79 Wh kg-1 at the power density of 824 W kg-1. This work provides a brilliant renewable candidate for the excellent energy storage device and a promising route design strategy for preparation of high performance and long life electrode materials. [Display omitted] • Design and fabrication of self-assembled Walnut shell-derived carbon and MOF composites. • WS@Ni-MOF/SPANI, as a new electrode material with sandwich structure, applied for supercapacitors for the first time. • The specific capacitance of WS@Ni-MOF/SPANI is greater than that of WS, Ni-MOF and SPANI. • Excellent cyclic stability of WS@Ni-MOF/SPANI (90.4%@20000). [ABSTRACT FROM AUTHOR]

In this work, a novel sensor based on gold nanoparticle-modified zirconium-metal-organic frameworks (MOF-801) and carboxyl-functionalized carbon nanotube (MWCNT-COOH) composite material was built successfully for electrochemical detection of guanine and adenine in DNA sample, which exhibits diverse advantages such as fast, convenience and high efficiency. Guanine and adenine were detected by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimal conditions, MOF-801/MWCNT-COOH/ AuNPs/GCE delivered linear DPV responses to guanine in the range of 0.8 ~ 60, 60 ~ 180 μM and the adenine in the range of 0.8 ~ 60, 60 ~ 180 μM with the low detection limit of 0.09 μM for guanine and 0.08 μM for adenine, respectively. The advantages of this method include simplicity, rapidity, high sensitivity, good selectivity as well as low cost. The modified GCE was successfully applied to the analysis of guanine and adenine in DNA samples. [Display omitted] • A new electrochemical sensor MOF-801/MWCNT-COOHs/AuNPs/GCE is prepared to simultaneously detecting guanine and adenine. • MWCNT-COOHs and AuNPs greatly improve the conductivity of the sensor and the resulted sensitivity. • This electrochemical sensor has good selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

In this present work, a carboxylated multi-walled carbon nanotubes (MWCNT-COOH) and covalent triazine framework (CTF-1) co-modified glassy carbon electrode (GCE) is prepared and used for simultaneous electrochemical detection of hydroquinone (HQ) and catechol (CC). Due to the synergistic effect between the high electrocatalytic activity and good conductivity of MWCNT-COOH and large surface area of CTF-1, the prepared modified electrode exhibits good selectivity and high sensitivity for the simultaneous determination of HQ and CC. In the neutral phosphate buffer, HQ and CC produce a pair of well-defined redox peaks on the MWCNT-COOH/CTF-1/GCE. The concentrations of CC and HQ show good linearity in the range of 2–280 μM and the detection limits of HQ and CC are 0.12 μM and 0.17 μM, respectively. The prepared electrochemical sensor can be employed to determine contents of HQ and CC in real samples. [Display omitted] • The MWCNT-COOH/CTF-1 composite exhibits superior electrocatalytic performance towards hydroquinone and catechol detection. • The research paves a feasible way to unlock high performance CTF electrode materials. • The sensor showed excellent specificity, good stability, and desirable reproducibility. [ABSTRACT FROM AUTHOR]

Mercury (Hg2+) is a highly hazardous and widespread environmental pollutant with bioaccumulative properties, so highly sensitive detection and effective removal of mercury in water environment are very necessary. Considering "soft base" property of N atom, N-containing organic groups cannot coordinate effectively with "hard acid" rare earth ions. A [Sm(ATPA) 1.5 (DEF)] n (Sm-MOF) (H 2 ATPA = 2-aminoterephthalic acid) containing free amino groups is constructed for simultaneous detection and removal of Hg2+ ions. Hg2+ can quench effectively the charge transfer emission of Sm-MOF in aqueous solution, and simultaneously induce the Sm3+ characteristic fluorescence emission of Sm-MOF. The results shows that the prepared Sm-MOF has an excellent selectivity and a high sensitivity for detecting Hg2+ with a wide linear range of 0.6–300 μM and a low detection limit of 0.87 μM. At the same time, the MOF is also employed to adsorb and remove Hg2+ in aqueous solution and it is found that over 97% of Hg2+ can be removed in approximately 2 h. [Display omitted] • Using Sm-MOF to detect and remove Hg2+ in aqueous solutions simultaneously. • 97% Hg2+ in aqueous solution was removed in 2 h. • The optical sensor delivered a low detection limit and a wide linear range. [ABSTRACT FROM AUTHOR]

[Display omitted] This paper studies the application of lanthanide metal-organic frameworks (Ln-MOFs) in fluorescence detection. The europium-based metal-organic frameworks (Eu-MOFs) are synthesized by a facile solvothermal method, and then the as-prepared MOF were further characterized by PXRD, FT-IR, TG, EDS, SEM, UV–vis spectra and fluorescence spectroscopy. The results demonstrate that Eu-MOF exhibits an intense red fluorescence, which can be readily observed by naked eye in solid state, good structural stability and fluorescence stability in aqueous solution or other organic solvents, especially high selectivity and sensitivity to Fe3+ and benzaldehyde and the visible color change by the naked eye under UV-light. This luminescent MOF can be used to detect Fe3+ and benzaldehyde in an aqueous environment with low detection limits of 0.027 μM for Fe3+ and 0.011 μM for benzaldehyde. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual-emission ratio fluorescent sensor (N-CDs/R-CDs@ZIF-8) was developed for Pb2+. • Spinach served as carbon source for green preparation of red fluorescent CDs. • Ultrasensitive Pb2+ detection down to 4.78 nM was delivered. A novel dual-emission ratio fluorescent sensor (N-CDs/R-CDs@ZIF-8) has been constructed successfully by introducing nitrogen-doped blue fluorescence carbon dots (N-CDs) and red fluorescence carbon dots (R-CDs) into the synthetic environment of ZIF-8 by a simple stirring method. The synthesized material not only inherits the excellent optical properties of N-CDs and R-CDs and the strong adsorption and accumulation performance of ZIF-8, but also shows strong fluorescence and structural stability in extreme environments. The presence of Pb2+ strongly causes the fluorescence quenching of N-CDs, but has almost no effect on the fluorescence of R-CDs. Therefore, a ratio fluorescence sensor is developed for the determination of Pb2+. Most importantly, the real-time fluorescence response shows that the composite material has a high selectivity and good sensitivity to Pb2+ determination, and the calculated LOD is 4.78 nM(S/N = 3) (0.05–50 μM), indicating that the material can be used as a potential fluorescent sensor for Pb2+ detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 @Ni-MOF was prepared and alkalized to obtain MoS 2 /Ni(OH) 2. • MoS 2 /Ni(OH) 2 has high specific capacitance and long cycling life for supercapacitor. • MoS 2 /Ni(OH) 2 was used to construct electrochemical sensor for HQ and CC. A nickel-based metal-organic framework (Ni-MOF) layer was in situ grown on the surface of the sheet MoS 2 to synthesize MoS 2 @Ni-MOF as a precursor. In order to improve the properties of the precursor material, the final MoS 2 /Ni(OH) 2 material was obtained by alkalizing the precursor material. Supercapacitors and electrochemical sensors were prepared by MoS 2 /Ni(OH) 2 composite material. The test indicates that alkaline treatment of Ni-MOF materials is helpful to improve electrochemical performance. MoS 2 /Ni(OH) 2 material used as supercapacitor electrode has a high specific capacitance of 2192 F g−1 and excellent cyclic stability (the capacitance retention rate remains 85.19% after 10,000 charge/discharge cycles). The hybrid supercapacitor (HSC) was assembled with MoS 2 /Ni(OH) 2 as the positive electrode and activated carbon as the negative electrode. The MoS 2 /Ni(OH) 2 //AC HSC device shows an excellent energy density of 50.58 Wh kg−1 at the power density of 800 W·Kg−1. In addition, the MoS 2 /Ni(OH) 2 modified GCE electrode is an excellent electrochemical sensor for the simultaneous determination of hydroquinone (HQ) and catechol (CC). The modified electrode provides wide linear ranges of 1 ∼ 500 and 2 ∼ 400 μM and low detection limits of 0.43 and 0.48 μM for HQ and CC, respectively (S/N=3). The MoS 2 /Ni(OH) 2 material can be applied to supercapacitors and electrochemical sensors, indicating that the material has great potential application value in energy storage and biosensing. [ABSTRACT FROM AUTHOR]

• The novel Mn-Ni double hydroxide composite was prepared by alkalizing the Mn/Ni-MOF-74 precursor. • MnNiDH shows high specific capacitance and excellent retention rate. • The assembled aqueous and all-solid-state devices display high energy densities and wide voltage window. MOF-derived hydroxides provide a promising platform for high performance supercapacitors as electrode materials. Herein, a novel manganese-nickel double hydroxide (MnNiDH) composite with special morphology has been successfully prepared by alkalizing the precursor Mn/Ni-MOF-74. Obtaining electrode material inherits the spear-shaped morphology of the precursor well and possesses a smaller particle size by potassium hydroxide treatment. The smaller particle size and rich microporous structure can shorten the ion or proton transport path, thereby improve its electrochemical activity and utilization. Benefiting from these specific properties, the resultant MnNiDH composite demonstrates a high specific capacitance of 2498 F g−1 at a current density of 1A g−1. The assembled aqueous device exhibits high energy density of 58.53Wh kg−1, meanwhile the all-solid-state device also displays energy density of 30.63 Wh kg−1 based on the outstanding voltage window of 0∼2.1 V. These results suggest that as-synthesized MnNiDH hold great potential for practical applications in the energy storage field. [ABSTRACT FROM AUTHOR]

A facile alkaline treatment stripping precursor strategy is developed for preparing MOF derived double hydroxide. The bimetallic MOFs material provides multi-type of redox reaction centres, and the hydroxide nanonanoflower obtained by alkali stripping Ni-MOF@Co-MOF effectively expands the "active area (circumference)" of the redox reaction. The exfoliated sheets expose more active sites, which are more favorable for effective contact with the electrolyte and facilitate the occurrence of redox reactions. The MOF derived double hydroxide maintains the structural and performance advantage of the MOF precursor as well as overcomes the disadvantages of poor conductivity and serious agglomeration of common hydroxide. As-synthesized electrode exhibited high specific capacity of 1088 C g−1 at 1 A g−1 and cycle retention of 94% after 12,000 cycles. Furthermore, assembled battery-supercapacitor hybrid device exhibits a maximum energy density of 66.5 Wh kg−1 at a power density of 825 W kg−1, and superior cycle retention and coulombic efficiency of 86% and 95% after 18,000 cycles, which shows that Ni-MOF@Co-MOF derived double hydroxide has good potential application value. [ABSTRACT FROM AUTHOR]

A pillar-like 3D lanthanide-organic framework (Eu-MOF) with opposite chirality was assembled according to previous report and fully characterized. The Eu-MOF exhibits excellent luminescence and structural stability in the aqueous solution or other organic solvents and good pH-independent luminescence stability in the pH range of 3–12. It is important to point out that the as-synthesized Eu-MOF can be developed as a highly selective and sensitive luminescent probe to rapidly detect Fe3+ (detection limit, 0.39 μM) and Al3+ (detection limit, 0.084 μM) from mixed metal ions, which can be explained by different response mechanisms and the color change are visible to the naked eyes under UV-lamp. In addition, it also exhibits highly sensitive for nitrobenzene (NB) (detection limit, 0.013 μM). Considering the obvious spectral response and low limit detection, the Eu-MOF can be employed as a promising multi-functional luminescent sensor for sensing metal ions and small organic molecules in the future. [ABSTRACT FROM AUTHOR]