MOFs@POMs-derived bimetallic oxide Fe(MoO) nanoparticles for sensitive colorimetric detection of salicylic acid in aspirin.

A colorimetric sensing method for salicylic acid (SA) was developed by designing and fabricating bimetallic oxide nanozymes. Firstly, by calcinating MIL-100(Fe)@PMo (MOFs@POMs) at different temperature, Fe(MoO)-Ts (T = 400℃, 500℃, 600℃, 700℃) nanoparticles (NPs) were successfully prepared. Secondly, by evaluating the peroxidase-like activities, Fe(MoO)-600 NPs shows the best peroxidase-like activity attributed to the Fenton-like effect and the synergistic coupling interaction between Mo and Fe.

Agar-Derived Slope-Dominated Carbon Anode with Puparium Like Nano-Morphology for Cost-Effective SIBs.

The microstructure of hard carbons (HCs) including interlayer distance and lateral ab direction and pore size distribution plays a key role in regulating the sodium ions storage performance. Herein, by employing the gelatinous agar as a model precursor, series P-doping HCs (P-HC-x, x = 1, 2, 3, 4) are facilely prepared in batches via controllably regulating its crosslinking state by phytic acid (PA) at a low carbonization temperature of 750 °C, in which PA plays three roles (acid, flame retardant, and P-doping precursor) in promoting the final structure of P-HC-x. Among those, the puparium like P-HC-2 with expanded carbon interlayer distance of 3.

Construction of a 12-Phosphomolybdate-based Coordination Polymer@Crumpled Graphene Balls Composite as Anode for Lithium Batteries.

To address the poor electronic conductivity and easily dissolved in electrolyte of polyoxometalates (POMs), and considering the high electrical conductivity and configuration advantages of crumpled graphene balls (CGBs), herein, a series of POM-based coordination polymers [Cu(pyttz) ]PMo @CGB (n, n=1, 2, 3) were successfully synthesized, and electrochemical lithium storage performance and lithium ion diffusion kinetics were comprehensively investigated. Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) study confirm that [Cu(pyttz) ]PMo @CGB (n, n=1, 2, 3) integrates the advantage of high electronic conductivity of CGB and excellent Li migration kinetics of POMs, which greatly ameliorates the electrochemical performances of POMs, among [Cu(pyttz) ]PMo @CGB (2) exhibits an excellent reversible specific capacity of around 941.4 mA h g at 0.

Increasing the peroxidase-like activity of the MIL-100(Fe) nanozyme by encapsulating Keggin-type 12-phosphomolybdate and covering three-dimensional graphene.

To improve the peroxidase-like activities of metal-organic frameworks (MOFs) as nanozymes, a ternary MIL-100(Fe)@PMo@3DGO nanocomposite was designed and fabricated by encapsulating Keggin-type HPMoO (PMo) with fast and reversible multi-electron redox processes and an electron-rich structure into MIL-100(Fe), then being covered by three-dimensional graphene (3DGO) with higher conductivity, larger surface area, higher porosity, and better chemical stability. As a consequence, the as-prepared MIL-100(Fe)@PMo@3DGO nanocomposite exhibits excellent peroxidase-like activities, namely, the lowest limit of detection (0.14 μM) in the range of 1-100 μM for glucose to date, to the best of our knowledge, attributed to the individual and synergistic effects of HPMoO, 3DGO and MIL-100(Fe).

ZIF-67 on Sulfur-Functionalized Graphene Oxide for Lithium-Sulfur Batteries.

How to overcome the problem of fast capacity fading and low sulfur utilization is the key to promote the practical applications of lithium-sulfur (Li-S) batteries. Based on the fact that sulfur-functionalized graphene oxide (GO-S) can avoid the loss of sulfur/polysulfides through the strong C-S interaction, and the zeolitic imidazolate framework (ZIF-67) can capture sulfur and catalyze lithium polysulfide (LiS, 4 ≤ ≤ 8), the combination of ZIF-S (ZIF-67 after combining with sulfur) with GO-S can be expected to be an excellent electrode material for Li-S batteries due to the synergistic effect. Herein, ZIF-S@GO-S () nanocomposites ( = 1, 2, and 3 for the mass ratio of ZIF-67/GO of 4:1, 6:1, and 8:1, respectively) as the cathode materials in Li-S batteries were successfully fabricated, and ZIF-S@GO-S (2) showed better electrochemical performances and cycle stability with a high specific capacity of 1529.

A template-free assembly of Cu,N-codoped hollow carbon nanospheres as low-cost and highly efficient peroxidase nanozymes.

Developing carbon-based materials with high catalytic performance and sensitivity has significance in low-cost and highly efficient nanozymes. Herein, for the first time, Cu,N-codoped hollow carbon nanospheres (CuNHCNs) with highly active Cu-Nx sites were successfully assembled through a template-free strategy, in which Cu-poly(-phenylenediamine) (Cu-PmPD) nanospheres were utilized as the source of Cu, N and C. Benefiting from the synergistic effect of the hollow spherical structure and optimized composition, the CuNHCN exhibits high affinity for 3,3',5,5'-tetramethylbenzidine and HO with 0.

Oxygen-powered flower-like FeMo@CeO self-cascade nanozymes: a turn-on enhancement fluorescence sensor.

Enzyme cascade reactions in organisms have sparked tremendous interest for their coupled catalysis-facilitated efficient biochemical reactions. However, multi-enzyme cascade nanozymes remain largely unused. In the work, flower-like porous ceria-based integrated enzymes (INAzyme), FeMo@CeO (FMC-), were readily prepared using an efficient thermally induced process.

Nanohybridization of CoS /MoS Heterostructure with Polyoxometalate on Functionalized Reduced Graphene Oxide for High-Performance LIBs.

To address the poor cycling stability and low rate capability of MoS as electrode materials for lithium-ion batteries (LIBs), herein, the CoS /MoS /PDDA-rGO/PMo nanocomposites are constructed via a simple hydrothermal process, combining the advantages of all three, namely, CoS /MoS heterojunction and polyoxometalates (POMs) provide abundant catalytically active sites and increase the multi-electron transfer ability, and the positively charged poly(diallyldimethylammonium chloride) modified reduced graphene oxide (PDDA-rGO) improve electronic conductivity and effectively prevent the aggregation of MoS , meanwhile stabilize the negatively charged [PMo O ] . After the electrochemical testing, the resulting CoS /MoS /PDDA-rGO/PMo nanocomposite achieved 1055 mA h g initial specific capacities and stabilized at 740 mA h g after 150 cycles at 100 mA g current density. And the specific capacities of MoS , MoS /PDDA-rGO, CoS /MoS , and CoS /MoS /PDDA-rGO were 201, 421, 518, and 589 at 100 mA g after 150 cycles, respectively.

An Unprecedented FeMo @Ce-Uio-66 Nanocomposite with Cascade Enzyme-Mimic Activity as Colorimetric Sensing Platform.

Introducing the idea of integrated design and cascade activity into nanozyme, the novel integrated nanozymes (INAzymes), FeMo @Ce-Uio-66 (FC-66(n)), were designed and synthesized by encapsulating iron-based polyoxometalates (FeMo ) into the ceria-based metal-organic framework (Ce-Uio-66). Due to the oxygen-driven reversible Ce /Ce couple sites, the "Fenton-like" effect by iron centers, the "nanoscale proximity" effects by nanocages, and their synergistic effects, FC-66(n) as INAzymes exhibit elegant cascade enzyme-mimic activities (oxidase-, peroxidase-, and Fenton-like activity), which realizes INAzyme activities based on polyoxometalates based metal-organic framework (POMOFs). By employing dopamine (DA) detection as a model reaction, a high-efficient fluorescent "turning-on-enhanced" platform under near neutral conditions was established.

Ferrocene-reduced graphene oxide-polyoxometalates based ternary nanocomposites as electrochemical detection for acetaminophen.

Developing a convenient and accurate method for the determination of acetaminophen (APAP) content is very vital, and ferrocene (Fc) based nanocomposites coupled with polyoxometalates (POMs) as electrochemical sensor is a promising approach to address the issues. Herein, a new ternary nanocomposite of Fc based carbon nanomaterials (Fc-rGO) with PMo (Fc-rGO/PMo, rGFP-n) was successfully fabricated, and the electrochemical activities and APAP detection of rGFP-n as electro-active materials were systematically investigated, and results of the differential pulse voltammetry (DPV) and electro-active surface area (0.0332 cm) show that rGFP-1 is an excellent electrochemical sensor for APAP, and the proportion of Fc in rGFP-n can affect the charge transfer between APAP and rGFP.

Synthesis of POMOFs with 8-fold helix and its composite with carboxyl functionalized SWCNTs for the voltammetric determination of dopamine.

Although many satisfactory studies have been developed for biomolecule detection, the complexity of biofluids still poses a major challenge to improve the performance of nanomaterials as electrochemical sensors. Herein, unprecedented polyoxometalate-based metal-organic frameworks (POMOFs) with 8-fold meso-helical feature, [Ag(trz)][PMoO] (PAZ), were synthesized and explored as electrochemical sensors to detect dopamine (DA). To improve the conductivity of PAZ and the binding ability with single-walled carbon nanotubes (SWCNTs), the nanocomposite of carboxyl functionalized SWCNTs (SWCNTs-COOH) with nano-PAZ (NPAZ), NPAZ@SWCNTs-COOH, was fabricated, and transmission electron microscopy (TEM) shows that NPAZ can interact stably and uniformly with SWCNTs-COOH, owing to more defect sites on the surface of SWCNTs-COOH.

Seeded Growth of Au@CuO Core-Shell Mesoporous Nanospheres and Their Photocatalytic Properties.

We report a facile synthesis of Au@CuO core-shell mesoporous nanospheres with tunable size in the aqueous phase seeded growth. The success of the current work relies on the use of a halide-free copper (Cu) precursor and n-oleyl-1,3-propanediamine as a capping agent to facilitate the formation of a copperish oxide shell with a mesoporous structure and the presence of mixed oxidation states of Cu. By varying the amount of spherical Au seeds while keeping other parameters unchanged, their diameters could be readily tuned without noticeable change in morphology.

Hollow POM@MOF-derived Porous NiMo @Co O for Biothiol Colorimetric Detection.

Developing highly active and sensitive peroxidase mimics for -cysteine ( -Cys) colorimetric detection is very important for biotechnology and medical diagnosis. Herein, polyoxometalate-doped porous Co O composite (NiMo @Co O ) was designed and prepared for the first time. Compared with pure and commercial Co O , NiMo @Co O (n) composites exhibit the enhanced peroxidase-mimicking activities and stabilities due to the strong synergistic effect between porous Co O and multi-electron NiMo clusters.

Development of a Uricase-Free Colorimetric Biosensor for Uric Acid Based on PPy-Coated Polyoxometalate-Encapsulated Fourfold Helical Metal-Organic Frameworks.

Developing a new cost-effective and reliable approach used for the detection of uric acid (UA) with no requirement of uricase is still very challenging. Herein, an easily realized, cost-effective, and uricase-free approach is reported for selective colorimetric biosensing of UA utilizing polypyrrole (PPy)-coated polyoxometalate-encapsulated fourfold helical metal-organic frameworks Ag[bimt][PMoO]·2HO (AgPMo) as a monolithic peroxidase mimic. It is demonstrated that the as-obtained AgPMo@PPy possesses excellent peroxidase-like activity originated from the synergistic effect to induce catalytic oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to green oxTMB in the presence of HO.

Effects of Polyoxometalates on the Hydroxylation of N-Heterocyclic Ligands.

Four polyoxometalate (POM)-based Cu complexes with the hydroxylated pyridine analogue 3-(2-hydroxylpyrid-4-yl)-5-(1-1,2,4-triazol-3-yl)-1,2,4-triazolyl (btpo), H{[Cu(btpo)](PWO)}·2HO (), H{[Cu(btpo)](PMoO)}·2HO (), H{[Cu(btpo)](SiWO)·SO (), and H{[Cu(btpo)](SiWO)}·8HO (), were synthesized hydrothermally under acid conditions. Single-crystal X-ray structural analysis reveals that 3-(pyrid-4-yl)-5-(1-1,2,4-triazol-3-yl)-1,2,4-triazolyl was hydroxylated into btpo in compounds -, again providing structural evidence for the Gillard mechanism, in which HO as a weak nucleophile can attack the α-C atom of N-heterocyclic molecules at a lower pH value (ca. 1.

Polyelectrolyte-functionalized reduced graphene oxide wrapped helical POMOF nanocomposites for bioenzyme-free colorimetric biosensing.

For the sake of effective colorimetric sensing-pattern, a sensitive colorimetric sensor was conceived based on polyoxometalates based metal-organic frameworks (POMOFs) and polydiallyldimethylammonium chloride functionalized reduced graphene oxide (PDDA-rGO) for the first time, in which PDDA as a "glue" molecule turns rGO nanosheets into general platforms for bonding POMOFs nanoparticles. Herein, a new POMOF compound with fascinating helices-on-helices feature, [Ni(Trz)(HO)][SiWO]4HO (Trz = 1,2,4-triazole) (abbreviated as NiSiW), was synthesized and characterized, then PDDA-rGO sheet as dispersive and conductive material was successfully introduced to NiSiW fabricating new PDDA-rGO/NiSiW-n nanocomposites, (abbreviated as PMPG-n). The resulting PMPG-n nanocomposites as peroxidase mimetic show excellent catalytic activities under extreme condition (pH value 2.

Assembly of 12-Tungstovanadate-Templated Nanocage and Nanocomposites with Single-Walled Carbon Nanotubes as Anodes in Lithium-Ion Batteries.

A new 12-tungstovanadate-templated 3D nanocage framework, Ag(μ-ttz)(HO)(VWO) (VW@MOCF), was designed based on a "molecular library", hydrothermally synthesized, structurally characterized, and explored as anode material for lithium-ion batteries (LIBs). Combination of the structural superiority of VW@MOCF with the good electrical conductivity of the single-walled carbon nanotubes (SWNTs) renders the VW@MOCF/SWNT-2 nanocomposite reasonable electrochemical performance and stability as anode materials of LIBs. The successful cooperative fabrication of nanocages and polyoxometalate (POMs) must initiate extensive research interests.

A polypyrrole-coated eightfold-helical Wells-Dawson POM-based Cu-FKZ framework for enhanced colorimetric sensing.

To explore a novel colorimetric biosensor with high sensibility and selectivity, a new Wells-Dawson-type polyoxometalate (POM)-based metal-organic framework (MOF) with an eightfold helix, [Cu(FKZ)(HO)][HPWO]·4HO (CuFKZPW) (HFKZ = 1-(2,4-difluorophenyl)-1,1-bis[(1H-1,2,4-triazol-1-yl)methyl] ethanol), was successfully synthesized; then, polypyrrole (PPy) was introduced to fabricate CuFKZPW/PPy(n) nanocomposites (n = 7%, 15%, 30%) via a facile in situ oxidation polymerization process. All the results indicate that CuFKZPW/PPy(15%) as a colorimetric biosensor exhibits lower limits of detection (0.07 μM towards HO and 0.

Molybdenum oxide-based metal-organic framework/polypyrrole nanocomposites for enhancing electrochemical detection of dopamine.

To overcome the poor conductivities and promote the application in the biosensors of metal-organic frameworks (MOFs), a simple approach was employed to improve their overall conductivity by adjusting the metal centers of MOFs and coating conductive polypyrrole (PPy) in the work. An unprecedented molybdenum oxide-based three-dimensional MOFs with helical channels (CuTRZMoO) was synthesized based on MoO, Cu ions and 1,2,3-trz for the first time, then combined with PPy to fabricate hybrid composites (CuTRZMoO@PPy-n) with both advantages. The CuTRZMoO modified glassy carbon electrode show high sensitivity for detecting the neurotransmitter dopamine (DA), and the CuTRZMoO@PPy-2 modified glassy carbon electrode has the highest catalytical activity to DA with the linear detection range from 1 μM to 100 μM and the detection limit of 80 nM (S/N = 3) by differential pulse voltammetry (DPV).

Insights into the lithium diffusion process in a defect-containing porous crystalline POM@MOF anode material.

Rechargeable lithium-ion batteries (LIBs) for potentially low-cost and high-energy-density storage have been intensively researched to meet ever-growing demands. Achieving higher storages and understanding the transporting and storing diffusion process of Li ions are still great challenges. Herein, a porous crystalline polyoxometalate-based metal-organic framework (POM@MOF), H[Cu(Htrz)(HO)][MoCuO]·3HO, with defect sites as a LIB electrode material is reported.

Heightened Integration of POM-based Metal-Organic Frameworks with Functionalized Single-Walled Carbon Nanotubes for Superior Energy Storage.

To increase the conductivity of polyoxometalate-based metal-organic frameworks (POMOFs) and promote their applications in the field of energy storage, herein, a simple approach was employed to improve their overall electrochemical performances by introducing a functionalized single-walled carbon nanotubes (SWNT-COOH). A new POMOF compound, [Cu (trz) Cl (H O) ][PW O ] (CuPW), was successfully synthesized, then the size-matched functionalized SWNT-COOH was introduced to fabricate CuPW/SWNT-COOH composite (PMNT-COOH) by employing a simple sonication-driven periodic functionalization strategy. When the PMNT-COOH nanocomposite was used as the anode material for Lithium-ion batteries (LIBs), PMNT-COOH(3) (CuPWNC:SWNT-COOH=3:1) showed superior behavior of energy storage, a high reversible capacity of 885 mA h g up to a cycle life of 170 cycles.

POMOF/SWNT Nanocomposites with Prominent Peroxidase-Mimicking Activity for l-Cysteine "On-Off Switch" Colorimetric Biosensing.

In order to explore novel colorimetric biosensors with high sensibility and selectivity, two new Keggin polyoxometalates (POMs)-based Cu-trz (1,2,4-triazole) metal-organic frameworks (MOFs) with suitable specific surface areas and multiple active sites were favorably fabricated; then single-walled carbon nanotubes (SWNTs) were merged with new POMOFs to construct POMOF/SWNT nanocomposites. Herein, POMOF/SWNT nanocomposites as peroxidase mimics were explored for the first time, and the peroxidase-mimicking activity of the prepared POMOF/SWNT nanocomposites is heavily dependent on the mass ratio of POMOFs and SWNTs, in which the maximum activity is achieved at the mass ratio of 2.5:1 (named PMNT-2).

Enhancing the colorimetric detection of HO and ascorbic acid on polypyrrole coated fluconazole-functionalized POMOFs.

A new fluconazole-functionalized polyoxometalate-based metal-organic framework (POMOF) [Ag(FKZ)(HO)][HSiWO] (AgFKZSiW) was successfully constructed, and its polypyrrole (PPy) coated composite AgFKZSiW@PPy was also obtained via a facile 'in situ' oxidation polymerization process. The peroxidase-like activity evaluation indicates that the maximized synergistic effect from the integration of PPy, SiW clusters, HFKZ drug molecules, and Ag ions deeply enhanced the overall performance. More importantly, AgFKZSiW@PPy exhibits the fastest response time (30 s) among all the reported peroxidase mimics to date, including the pristine AgFKZSiW (2 min).

Ce self-doped CeO/FeOCl: an efficient Fenton catalyst for phenol degradation under mild conditions.

Herein, a novel Ce3+ self-doped CeOx/FeOCl composite was successfully prepared by a facile method for the first time, which showed remarkable catalytic activity as a Fenton catalyst in the degradation of phenol under the conditions of a neutral solution, room temperature and natural light. In CeOx/FeOCl, 5.23% CeOx is the optimal condition, and the degradation constant (k) of CeOx/FeOCl is greater than that of FeOCl by a factor of 10.