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Among a large variety of energy storage technologies, supercapacitors possess special advantages such as rapid charge/discharge, high power density, safety, and environmental friendliness to meet the requirement of specific applications. The common electrode materials of supercapacitors, including porous carbon, conductive polymers, and metal oxides/hydroxides, have their own benefits and drawbacks in energy density and stability. Owing to the big surface area and controllable porosity, the metal-organic frameworks (MOFs) have been explored as important candidates for supercapacitor applications. This mini-review focuses on the recent advances of MOF-based materials including pristine MOFs, MOFs composite materials, and MOF-derived materials in the development of long cycling life supercapacitors. The devices discussed here mean those with capacitive retention rates of more than 90% after 10,000 cycles and high energy density. In addition, we also describe the fundamental knowledge of supercapacitors, highlight the stabilization mechanism of MOFs, and propose the strategies to enhance the stability of MOF-based supercapacitor electrodes. • The fundamental knowledge of supercapacitor is illustrated. • The fundamental mechanisms of MOFs stabilization are emphasized. • Recent advances of MOF-based long cycling stability supercapacitors are reviewed. • The strategies to enhance the stability of MOF-based supercapacitors are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Downsizing a benchmark MOF into uniform nanosized materials. • Enhanced gas adsorption rate and capacity. • High-performance separation of propane and propylene. The separation of propane/propylene mixtures to produce polymer-grade propylene represents an important yet challenging task in the petrochemical industry. Metal-organic frameworks (MOFs) hold particular promise for the energy-efficient adsorptive separation of propane/propylene, in light of their structural diversity as well as highly tunable pore dimensions. MOFs exhibiting selective molecular exclusion for propylene over propane render exceptionally high adsorption selectivity. However, the relatively low adsorption capacity and/or slow diffusion kinetics have largely limited their separation efficiency. Here we report the fabrication of nano-sized crystals of a MOF-based splitter for propane and propylene. Compared to the micro-sized MOF samples, the nanocrystals display enhanced adsorption kinetics as well as notably improved adsorption capacity, making a new record with the highest efficiency for the separation of propane/propylene among all reported MOF-based splitters. Our study may shed light on the development of MOF-based adsorbents with optimal efficiency for industrially challenging gas separations. [ABSTRACT FROM AUTHOR]

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]

A metal porous carbon (Ni@NC) supported nickel/cobalt layered double hydroxide (NiCo-LDH) (Ni@NC@NiCo-LDH) with a cauliflower morphology was synthesized by a successive double template method. At first a nickel metal-organic framework (Ni-MOF) was prepared and used as a sacrifice template to produce metal porous carbon (Ni@NC). Then the prepared conductive porous carbon material was exploited as a substrate for in-situ growing of ZIF-67 on its surface. Lastly the obtained Ni@NC@ZIF-67 was further used as a sacrifice template to prepare the final electrode material Ni@NC@NiCo-LDH by Ni2+ etching and co-precipitation. The cooperation of Ni@NC with excellent conductivity and NiCo-LDH with superior pseudocapacitive property yielded a synergistic effect, which effectively improved the electrochemical performance of the resulted electrode material. And the special flower morphology exposed more redox active sites and provided proper charge transport path for enhanced electrochemical performance. The prepared Ni@NC@NiCo-LDH exhibited a high specific capacitance of 1761.8 F·g−1 at the current density of 1 A·g−1. The assembled Ni@NC@NiCo-LDH//AC asymmetric supercapacitor also displayed an acceptable energy density (39.27 Wh·kg−1 at the power density of 757.21 W·kg−1) and ultrahigh cycling stability (94.74% capacitance retention after 25000 cycles at 10 A g−1). [Display omitted] • Ni@NC@NiCo-LDH was prepared by combination of Ni@NC and NiCo-LDH for the first time. • Ni@NC@NiCo-LDH had a big specific capacitance. • The assembled supercapacitor with Ni@NC@NiCo-LDH and AC had excellent cycle stability. [ABSTRACT FROM AUTHOR]

Nickel-cobalt sulfides (NiCo 2 S 4) with abundant valence states are promising electrode materials for multiple faradaic reactions in hybrid supercapacitors. However, the slow electron transfer kinetics and lack of active sites restrict its electrochemical activity. Herein, an effective synthesis strategy was proposed to synergistically improve the electrochemical performance of NiCo 2 S 4 through one-step in-situ carbonization-vulcanization method of metal-organic frameworks (MOF). Through rational selection and optimization of the Ni:Co ratio, the fibre-assembled urchin-like 3D nanoflowers (denoted as NCSC) possess abundant sulfur vacancies and appropriate porosity. Interestingly, the S vacancies can expose more redox active sites, while the expandable 3D carbon conductive network can accelerate electron transport. Furthermore, the electrical conductivity and interfacial activity is synergistically enhanced by strong electronic coupling effects. Experimental results reveal that the NiCo 2 S 4 /C exhibit excellent electrochemical performance as a battery-type electrode material. The specific capacitance is 1934 F·g−1 (967 C·g−1) at 1 A·g−1 and the capacitance retention is 93.2% after 5000 cycles at 5 A·g−1. The assembled hybrid supercapacitor device (NiCo 2 S 4 /C//AC) exhibits an exceptionally high energy density of 50.24 Wh·kg−1 at power density of 800 W·kg−1. These results have significant implications for the optimization of the transition metal compounds for electrochemical energy-storage devices. [Display omitted] • The sulfur vacancy-rich 3D fibrous nanoflowers is synthesized successfully. • The in situ generated carbon network modulates the intrinsic electronic/surface structure. • One-step vulcanization-carbonization achieves highly dispersive S vacancies-rich NiCo 2 S 4. • Highly graphitized 3D nanostructures shows high specific capacitance of 1934 F·g−1 at 1 A·g−1. [ABSTRACT FROM AUTHOR]

Although peroxidase-like nano-enzymes have been widely utilized in biosensors, nano-enzyme based biosensors are seldom used for both quantitative analysis of H 2 O 2 and differentiation of isomers of organic compounds simultaneously. In this study, a dual-functional mimetic enzyme-based fluorescent sensor was constructed using metal-organic frameworks (Bi-MOFs) with exceptional oxidase activity and fluorescence properties. This mimetic enzyme sensor facilitated quantitative analysis of H 2 O 2 and accurate discrimination of phenylenediamine isomers. The sensor exhibited a wide linear range (0.5–400 μM) and low detection limit (0.16 μM) for the detection of H 2 O 2. Moreover, the sensor can also be used for the discrimination of phenylenediamine isomers, in which the presence of o-phenylenediamine (OPD) leads to the appearance of a new fluorescence emission peak at 555 nm, while the presence of p-phenylenediamine (PPD) significantly quenched its fluorescence due to the internal filtration effect. The proposed strategy exhibited a commendable capability in distinguishing phenylenediamine isomers, thereby paving the way for novel applications of MOFs in the field of environmental science. [Display omitted] • A mimic enzyme fluorescent probe realized detection of H 2 O 2 and distinction of phenylenediamine isomers, simultaneously. • A green, simple and eco-friendly method is used to visual analysis. • H 2 O 2 in real samples was detected by the proposed fluorescent probe. [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]

• Hetero-phase hybridization strengthens internal electric field. • Covalent interaction creates nucleation sites and stabilizes the hybrids. • In-situ growth of MOF on Co 2 (OH) 2 CO 3 eliminates self-aggregation. • Controlled synthesis of the heterostructure with MWCNTs aid produces synergistic effect. • The integrated electrode delivers superior rate performance at high current density. In this work, bimetallic nickel-cobalt based metal organic framework (MOF) is in-situ grown on 2D laminar Co 2 (OH) 2 CO 3 with multi-walled carbon nanotubes (MWCNTs) aid to form nanoflower-like hierarchical porous heterogeneous structure for advanced supercapacitor application. Benefitting from the low crystal surface energy of Co 2 (OH) 2 CO 3 , its intersection and connection with MOF generate convenient electron path and open channel for ionic transmission, and large contact area. The high aromaticity of MWCNTs slows down destruction for MOF structure from water molecule through providing hydrophobic environment, guaranteeing stable presence of the resulting composite in aqueous electrolyte. The synergistic effect of Ni/Co with high redox activity in bimetallic NiCo-MOF provides rapid and multiple redox reactions for enhanced capacitance. Taking full advantage of promising merits of individual components, the optimized NiCo MOF-Co 2 (OH) 2 CO 3 nanosheet-MWCNT 30 (NCM-NS-CNT 30) composite under MWCNT dosage of 30 mg delivers greatly enhanced specific capacitance (1773 F g−1 at 1 A g−1) and obviously improved rate performance (96.5 % retention at 10 A g−1). Based on it, the fabricated hybrid supercapacitor (HSC) NCM-NS-CNT 30 //AC presents comparatively good energy density (30.625 Wh Kg−1), superior to most recently reported Ni, Co-based supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel dual-emission ratiometric fluorescent sensor (CDs@Eu-MOFs) has been synthesized successfully by encapsulating water-soluble fluorescent CDs into the chambers of Eu-MOFs via a simple one-pot hydrothermal method, which can be used for the detection of Hg2+ in environmental water samples. The synthesized CDs@Eu-MOFs inherited simultaneously the excellent luminescence performance of Eu3+ and CDs and exhibited good structural and fluorescence stability in aqueous solution. The presence of Hg2+ changed the fluorescence intensity of CDs, while the fluorescence intensity of Eu-MOFs hardly changed, which could be used as the recognition part and the reference part respectively to construct the ratiometric fluorescence sensor. The obtained Hg2+ fluorescent probe showed a wide linear range (0–300 μM) and a low detection limit (0.12 nM). The developed method can be used as a multi-functional fluorescent sensor with high sensitivity and good selectivity for the determination of Hg2+ in actual water samples. Image 1 • CDs@Eu-MOFs composite was prepared using in-situ synthesis method. • A green, simple, eco-friendly strategy for synthesizing CDs was established. • The ratiometric fluorescence sensor can recognize Hg2+ highly sensitively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual-emission ratiometric fluorescent sensor Eu/CDs@UiO-66-(COOH) 2 was synthesized. • Eu/CDs@UiO-66-(COOH) 2 had high structural and fluorescence stability in aqueous solution. • The probe was used for sensitive and selective detection of CO 3 2– in actual samples. Carbonate ion (CO 3 2–) is an anion essential for the maintenance of life activities and is of great importance to human health. Here, a novel ratiometric fluorescent probe Eu/CDs@UiO-66-(COOH) 2 (ECU) was prepared by introducing europium ions (Eu3+) and carbon dots (CDs) into the UiO-66-(COOH) 2 parent framework under the guidance of a post-synthetic modification strategy and used for the detection of CO 3 2– ion in the aqueous environment. Interestingly, when CO 3 2– ions were added to the ECU suspension, the characteristic emission of carbon dots at 439 nm was significantly enhanced, while the characteristic emission of Eu3+ ions at 613 nm was reduced. Therefore, the detection of CO 3 2– ions can be realized through the peak height ratio of the two emissions. The probe had a low detection limit (about 1.08 μM) and a wide linear range (0–350 μM) for the detection of carbonate. In addition, the presence of CO 3 2– ions can cause a significant ratiometric luminescence response and resulted obvious red-to-blue color shift of the ECU under UV light, which will facilitate visual analysis by the naked eye. [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]

Arginine (Arg) is considered a valuable biomarker for various diseases, including cystinuria, and its concentration level holds significant implications for human health. To achieve the purposes of food evaluation and clinical diagnosis, it is imperative to develop a rapid and facile method for selective and sensitive determination of Arg. In this work, a novel fluorescent material (Ag/Eu/CDs@UiO-66) was synthesized by encapsulating carbon dots (CDs), Eu3+ and Ag + into UiO-66. This material can serve as a ratiometric fluorescent probe for detecting Arg. It exhibits a high sensitivity with a detection limit of 0.74 μM and a relatively broad linear range from 0–300 μM. After dispersing the composite Ag/Eu/CDs@UiO-66 in an Arg solution, the red emission of Eu3+ center at 613 nm was significantly enhanced, while the characteristic peak of CDs center at 440 nm remained unchanged. Therefore, a ratio fluorescence probe could be constructed based on the peak height ratio of the two emission peaks to achieve selective detection of Arg. In addition, the remarkable ratiometric luminescence response induced by Arg results in a significant color transition from blue to red under UV-lamp for Ag/Eu/CDs@UiO-66, which was convenient for visual analysis. [Display omitted] • A ratiometric fluorescent probe Ag/Eu/CDs@UiO-66 realized biomarker detection of cystinuria. • A green, simple and eco-friendly method is used to synthesize CDs. • Arginine in real samples was detected by the proposed fluorescent probe. [ABSTRACT FROM AUTHOR]

• A hollow structure PZ-20 was prepared by controlling the ligand exchange time. • Hollow structure r-NiCo 2 S 4 with sulfur vacancies for more active sites and redox reactions was synthesized. • The fabricated structure exhibited an ultra-high specific capacitance. • The assembled device presented an high energy density of 43.80 Wh·kg−1 under 800 W·kg−1. Defect and hollow structure on transition metal sulfides can produce abundant active sites and shorten electron/ion diffusion paths, improving the conductivity of electrochemically active materials. In this study, an effective strategy was proposed for preparing r-NiCo 2 S 4 electrode materials with sulfur vacancies and hollow structures and resulted excellent electrochemical performance through ligand exchange followed chemical reduction. Due to the unique structure, the prepared r-NiCo 2 S 4 electrode exhibited excellent specific capacitance (1406.4 F g−1 at 1 A g−1) and rate capacity (90.03%). Additionally, a hybrid supercapacitor r-NiCo 2 S 4 //AC HSC was assembled using r-NiCo 2 S 4 as the positive electrode and AC as the negative electrode. It presented an excellent energy density of 43.8 Wh kg−1 under 800 W kg−1 and cycling performance with 93.93% capacity retention after 10,000 cycles at 5 A g−1. This study provided a simple strategy for design and optimization of electrode materials with a unique hollow structure and sulfur vacancies. [ABSTRACT FROM AUTHOR]

Considering the high electrical conductivity of carbon dots (CDs) and good oxidation-reduction property of polyoxometalates (POMs), a novel CDs coated POMs /metal organic frameworks (POMOFs) composition structure, CDs@PMo 12 /Ni-MOF, was prepared by hydrothermal reaction in this work. PMo 12 was encapsulated in the Ni-MOF framework to form the POMOF composite material, which realized the fixation of water-soluble [PMo 12 O 40 ]3- (PMo 12). A comparison study on the cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) of the resulting CDs@PMo 12 /Ni-MOF with different compositions revealed that 6CDs@PMo 12 /Ni-MOF was better formulation in terms of specific capacity (748.8 C·g−1 at 1 A·g−1) and rate performance (75.93 % at 10 A·g−1). Furthermore, a hybrid supercapacitor device was assembled using 6CDs@PMo 12 /Ni-MOF as positive electrode and activated carbon (AC) as negative electrode, which showed an high energy density of 39.22 Wh·kg−1 under 749.9 W·kg−1 and excellent cyclic stability (98.4 % for 20000 cycles at 5 A·g−1). [Display omitted] • Fixation of water-soluble PMo 12 was realized to form POMOF composite material. • CDs@PMo 12 /Ni-MOF has excellent rate performance and cycle stability. • 6CDs@PMo 12 /Ni-MOF exhibits high specific capacitance and energy density. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotube (MWCNT)/Ni-Mn-S composites are derived from MWCNT/Ni/Mn bimetallic metal-organic framework (MOF) for supercapacitor electrodes. Electroconductive MWCNT is introduced into Ni-Mn-S to form a three-dimensional interconnected structure due to the covalent interaction between Ni atoms and C atoms. During energy storage, MWCNT serves as miniature current collector to shorten pathway of electron collection and transmission. In addition, S2- etching agent with Kirkendall effect makes edges and surfaces of the resulted sulfide structures rougher provide more active sites and improves electrochemical performance compared with precursors. By finely adjusting Ni/Mn molar ratio, the prepared MWCNT/Ni-Mn-S composite achieves excellent properties. As-prepared MWCNT/Ni-Mn-S(3:2) exhibits high specific capacitance of 1041 mAh g−1 at 1 A g−1 and good cyclic stability. The capacitance retention reaches 83.3% after 10,000 cycles. The assembled MWCNT/Ni-Mn-S(3:2)//AC hybrid supercapacitor (HSC) also shows high energy density of 25.33 Wh Kg−1 at power density of 829 W Kg−1 and outstanding cycling stability (93.3% after 20,000 cycles), which illustrates MWCNT/Ni-Mn-S(3:2) has important potential in supercapacitor. [Display omitted] • MWCNT/Ni-Mn-S(3:2) is derived from corresponding MWCNT/MOF-Ni/Mn for supercapacitors. • MWCNT/Ni-Mn-S(3:2) electrode shows high specific capacitance of 1041 mAh g−1. • Assembled MWCNT/Ni-Mn-S(3:2)//AC HSC delivers high specific capacitance and excellent cyclic stability. [ABSTRACT FROM AUTHOR]

• Ni-MOF on MXene is vulcanized to sandwiched p-MXene/Ni 3 S 4 /CuS in the presence of copper. • p-MXene/Ni 3 S 4 /CuS show the remarkable specific capacitance. • The p-MXene/Ni 3 S 4 /CuS//AC has a high energy density and ultrahigh cyclic stability. [Display omitted] Metal-organic frameworks (MOFs) have ordered porous structure and intriguing properties for supercapacitors, however, poor conductivity and cycle stability limits their application. To solve these problems, hence, a simple strategy is proposed, by which MOFs are in-situ grown in the porous conductive p-MXene substrate. And then, along with the introduction of CuS, the grown Ni-MOF is derived to Ni 3 S 4 , which is more stable and more electrochemically active. Due to higher contact area, excellent synergistic effect and more exposed active sites, the prepared sandwiched p-MXene@Ni 3 S 4 /CuS nanostructure displays a big specific capacitance (1917 F·g−1) and superior cycling performance (91.2%@30000). What's more, the assembled p-MXene@Ni 3 S 4 /CuS//AC asymmetric device delivers a high energy density of 87.62 Wh·Kg−1 at the power density of 775.02 W·Kg−1, suggesting that this material provides a brilliant candidate for energy storage. [ABSTRACT FROM AUTHOR]

Creatinine (Cre) measurement in biological fluids is an increasingly important clinical measure for evaluating renal insufficiency, thyroid dysfunction, and muscle injury. Therefore, a simple, fast, and reliable Cre analysis method is of great significance to human health. Herein, a novel ratiometric fluorescence sensor, Ag-Eu-MOF-808-EDTA, was synthesized by introducing ethylenediaminetetraacetic acid (EDTA), Ag+, and Eu3+ into the framework of MOF-808 through three steps of post-synthesis modification, and was used to detect Cre in PBS buffer of pH 7.2 at 35 °C with a "turn-on" ratio response in the presence of various interfering ions and several biomolecules. In this strategy, the characteristic emission of Eu3+ at 551 nm can be turned on due to coordination between Cre and Ag+, while emission at 613 nm is independent of Cre, which produces a significant ratio response change throughout the cycle. Experimental results showed that the ratio fluorescence sensor displayed a wide linear range for Cre from 0.5 to 350 μM with a low detection limit of 0.42 μM. Finally, a good recovery rate (96.7–102.9%) and appropriate relative standard deviation (RSD <2.39%, n = 3) were obtained during the determination of creatinine in real urine and serum. This work provides additional insights into the detection of creatinine in clinical blood samples. [Display omitted] • Ag-Eu-MOF-808-EDTA was prepared by three-step post-synthetic modification. • The material was used for a ratiometric fluorescence sensing of creatinine. • The ratiometric sensor showed a wide linear range and low detection limit for Cre. [ABSTRACT FROM AUTHOR]

[Display omitted] In this study, metal–organic backbone (UiO-66-NH 2) and thionyl chloride functionalized carbon nanotubes (COCl-MWCNT) were successfully synthesized, and introduced into carbon black (CB) for fabricating novel electrochemical sensor UiO-66-NH 2 /COCl-MWCNT/CB/GCE towards simultaneous determination of dihydroxybenzene isomers hydroquinone (HQ), catechol (CC) and resorcinol (RC). Due to large surface area, excellent conductivity, good electrocatalytic activity and high stability the developed composite modified electrode delivered excellent analytical performance for these three analytes. Under optimal conditions, differential pulse voltammetric (DPV) currents showed good linear relationships with the concentrations of HQ, CC and RC with low detection limits (0.24 μM, 0.11 μM, 0.47 μM) and wide detection ranges (1–1000 μM and 5–1000 μM). In addition, this sensor demonstrated favorable reproducibility, stability and good selectivity for HQ, CC and RC and possessed a great potential for selective detection of dihydroxybenzene isomers in environmental water samples. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) can perform later transformation without compromising the integrity of the overall framework, and a variety of chemical reactions can be used to modify framework components. Postsynthetic modification (PSM) of MOFs has been developed as an alternative strategy that can expand the range of MOF functional groups. Considering the p-type semiconducting visible light active performance of CuBi 2 O 4 (CBO) and the unique porous nanostructure and stability of zeolitic imidazolate framework-8 (ZIF-8), in this work, a novel core-shell coordination assembled hybrid based on p-type semiconductor@MOFs (Eu-CBO@ZIF-8) is prepared for the first time via in-situ growth and postsynthetic metal exchange. A series of detailed characterizations were conducted to confirm the successful synthesis of the material. Moreover, we are focusing on using this material as a new dual-functional sensing material for simultaneous detection and removal of tetracycline (TC), which shows an outstanding analytical performance with a low detection limit of 17 nM, relatively broad linear range (0–70 μM), fast response of less than 120 s, and excellent adsorption performance (377.07 mg g−1) toward TC. In addition, the sensitive luminescence response caused by TC makes Eu-CBO@ZIF-8 undergo a significant color transition from dark to red under UV-lamps, which is beneficial for visual analysis with the naked eye. The possible detection and adsorption mechanisms, including coordination between Eu3+ and the detected substance, the hydrogen bond between ligand and the detected substance, were further discussed. In addition, the practical feasibility of Eu-CBO@ZIF-8 for TC sensing was also studied, with a satisfactory recovery rate of 96.9%–104.6% and RSD ≤3.32%. These results indicate that this material can be used for the detection and adsorption of TC in actual samples. [Display omitted] • A core-shell coordination assembled hybrid Eu-CBO@ZIF-8 is prepared. • The material is used for simultaneous detection and removal of tetracycline (TC). • Significant color change under UV-lamp makes it adequate to visual analysis of TC. [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]

• A simple ultrasound-assisted method was used to synthesize nitrogen-containing p - π conjugated-organic ligands. • Nitrogen-containing conjugated organic ligands have good conductivity. • Carbon-enriched MOFs and derived porous carbon have excellent electrochemical performance. • The change law of electrochemical performance was explored with gradient temperature. • The MOF-B-600//AC ASC device exhibits a high energy density of 63.62 Wh·kg−1 at power density of 400 W·kg−1. [Display omitted] This article aims to use nitrogen-doped metal p - π conjugated-organic frameworks and derived carbon-rich electrode materials for high-performance electrode materials. Nitrogen-doped contributes to the energy storage performance, and the p-π conjugated-organic ligands of the conjugated system can not only improve the stability of the structure, but increase the conductivity of the material. Gradient carbonization can explore the maximum electrochemical potential of MOF-B, from which the previous 1271.0 increased to 2727.5 F·g−1 at a current density of 1.0 A·g−1. The excellent capacitance retention rate is 86.67% of the initial value at a high current density after 20,000 cycles. Besides, the MOF-B-600//AC also shows a high energy density of 63.62 Wh·kg−1 at a power density of 400 W·kg−1 and good coulomb efficiency of 90.7%. As a result, the excellent electrochemical performance of the nitrogen-doped and carbon-enriched MOF-B-600 has potential application prospects in energy storage devices. [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]

The transition metal selenides have aroused wide concern due to their potential characteristics in the energy storage and conversion. The formation of multivariate MOFs attracts much research attention and provides the essential guarantee for multivariate mixed-metal selenides. Herein, a series of isostructural MOF-74 materials with different divalent metals were prepared by changing the molar ratios of nickel to cobalt. After selenizing, CoSe 2 , NiSe 2 and three kinds of mixed-metal selenides were easily obtained, prompting us to systematically research the effect of different metal species and molar ratios on the electrochemical performance of the mixed-metal selenides. It is found that mixed-metal selenides derived from MOF-74 display much better performance than single metal selenides, and NiCoSe-4 with a Ni/Co molar ratio of 4:1 demonstrates a high specific capacity of 211 mAh g−1 at a current density of 1 A g−1. What's more, the assembled asymmetric supercapacitor NiCoSe-4//AC shows a high energy density of 61.24 Wh kg−1 at power density of 800 W kg−1, which suggests that NiCoSe-4 as a promising electrode material possesses further research value and potential for practical applications in energy storage fields. Image 1 • CoSe 2 , NiSe 2 and three kinds of mixed-metal selenides were easily obtained by selenizing different isostructural MOF-74 materials. • Mixed-metal selenides of electrochemical performance derived from MOF-74 display much better than single metal selenides, and NiCoSe-4 demonstrates a high specific capacity of 211 mAh g−1 at a current density of 1 A g−1. • The assembled NiCoSe-4//AC exhibits high energy density of 61.24 Wh kg−1 at power density of 800 W kg−1. The capacitance retention and Faradic efficiency of the NiCoSe-4//AC are 91% and 89% after 12,000 cycles at a current density of 10 A g−1. [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]

In this present paper, a novel layered multi-metal sulphide was reported as a positive electrode material with abundant electroactive sites and redox reaction centres. Molybdenum and sulfur elements were introduced into the metal-organic frameworks (M-MOF: M = Ni, Co and Ni/Co) to synthesize layered MMoS x by a hydrothermal method. The electrochemical performance comparison of MOFs and six electrode materials demonstrated that NiCoMoS x electrode materials had the best electrochemical performance and the highest specific capacitance. The highest specific capacitance could reach 2595 F g−1 at a current density of 1 A g−1. The NiCoMoS x electrode material also had an excellent cycle stability with a retention rate of 90.8% after 10,000 charge and discharge cycles. In addition, the as-assembled NiCoMoS x //AC assymmetric supercapacitor (ASC) device exhibited a maximum energy density of 48.2 Wh·kg−1 at a power density of 807.2 W kg−1, and the capacity retention rate after 10,000 charge and discharge cycles was 91.6%. This electrochemical performance indicated that this kind of material had a good market development prospect. • Six kinds of materials were synthesized by hydrothermal method to make working electrodes, and electrochemical properties were tested and compared. • It is proved that cobalt-nickel composite has higher specific capacitance and better electrochemical performance after molybdenum-doped vulcanization with MOF as precursor. • NiCoMoS x electrode material has good electrochemical properties and excellent cycling stability. • The assembled asymmetric supercapacitor has good energy storage and can light up red LED. [ABSTRACT FROM AUTHOR]

Nitrogen sulfur co-doped bimetal nanocomposites (NS-BNs) are prepared through vulcanization and annealing using bimetallic Ni/Co-MOF as a precursor. The nitrogen sulfur co-doped bimetal nanocomposites have abundant electroactive sites and redox reaction centres, which exhibit remarkable electrochemical performance as electrode materials for supercapacitor. The specific capacitance could reach 1529 F g−1 at a current density of 1 A g−1 and excellent cycle stability (retention rate of 89.29% after 10000 cycles). After the current density is expanded ten times, the specific capacitance can still reach 1069 F g−1, indicating superior rate performance. Furthermore, the assembled asymmetric supercapacitor displayed a high energy density of 41.04 Wh kg−1 at power density of 750 W kg−1. As a result, non-metal doped nanocomposites material has promised applications for electrochemical supercapacitors. Image 1 • Advanced asymmetric supercapacitor device assembled by nitrogen sulfur co-doped bimetal nanocomposites. • Outstanding electrochemical behaviour and ultrahigh specific capacitance of 1529 F g−1 at 1 A g−1. • High energy density of 41.04 Wh kg−1 at power density of 750 W kg−1. • Remarkable long term cycle stability with 90% after 10000 charge-discharge cycles. [ABSTRACT FROM AUTHOR]