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Mixed Co-based spinel oxides were synthesized via a simple MOF/MXene pyrolysis–reorganization strategy, which revealed that the coupling effect between Co3O4 and Co2TiO4 is crucial for improving OER activity.

Ar plasma technology tunes sulfur vacancies in polymetallic heterogeneous sulfide catalysts generated from MOG precursor to boost oxygen release.

Morphology and interfacial engineering of heterogeneous MOF/MXene hierarchically-porous nanorods on Ni foam deliver exceptional robust stability and energy density in hybrid supercapacitor application.

Dynamic long-lived multicolor room temperature afterglow and circularly polarized luminescence (CPL) are promising for optoelectronic applications, but integration of these functions into a single-phase chiroptical material is still a difficult and meaningful challenge. Here, a nitrogen-doped benzimidazole molecule 1

Developing efficient metal-organic framework (MOF)-based electrocatalysts with improvable activity and persistence toward the methanol oxidation reaction (MOR) is attracting great research attention but still remains an enormous challenge. Herein, a facile strategy, hydrangea-shaped nickel hydroxide template-directed synthesis of the hierarchically structured Ni-MOF on the Ni(OH)2 heterocomposite (denoted as Ni-Ni) for efficient MOR, is developed. The unique hierarchical structure and synergistic effect of the heterocomposite afford more exposed active sites, a facile ion diffusion path, and improved conductivity, favorable for improving MOR catalytic performance. Remarkably, the optimized Ni-Ni-2 material delivers an excellent activity with a high peak current density (24.6 mA cm-2). Furthermore, to prove the universality of this strategy, NixCu1-x(OH)2 isometallic hydroxide was used as the precursor, and a series of MOF-74/CuxNi1-x(OH)2 (denoted as Ni-NiCu) heterogeneous materials have been prepared and could be used as an effective electrocatalyst to catalyze MOR. The results indicate that this strategy can be used in the synthesis of other new composite materials with specific hierarchical structures for a more efficient electrocatalytic system.

Integrating the merits of different components to construct heterostructures for energy storage and conversion has attracted intensive attention. Herein, taking advantage of bimetallic MOFs and transition bimetal hydroxide, we have successfully used nanoflower-like Ni1−xCox(OH)2 as both the precursor and template to in situ construct three dimensional (3D) NiCo-MOF@Ni1−xCox(OH)2 (denoted as MOF@TMH) hierarchical heterostructures. Benefiting from the optimized composition with hierarchical heterostructures assembled by ultrathin nanosheets, MOF@TMH-2 possesses rich effective active sites and high electrochemical reactivity, delivering superior pseudocapacitor performance with a specific capacitance of 1855.3 F g−1 at 2 A g−1 and good rate performance. Besides, MOF@TMH-2 also exhibits excellent OER activity with small overpotentials of 193 mV and 310 mV at 10 and 100 mA cm−2, respectively.

Ni-based materials have emerged as promising anode electrocatalysts that can replace noble metals for the methanol oxidation reaction (MOR). However, the potential applications of Ni-based metal–organic gels (Ni-MOGs) in MOR have rarely been recognized. In this study, using the readily prepared Al-MOG (MIL-53(Al)) without MOR activity as a template, we fabricated AlNi-MOG and AlNi-based trimetallic MOGs (Cu, Co and Fe) by a simple solvothermal method, which could be directly used as electrocatalysts for the MOR. Among them, the as-obtained AlNiCu-MOG exhibited better MOR activity with an area-specific peak current density of 17.1 mA cm−2 than AlNi-MOG (11.46 mA cm−2), which could be attributed to the electron coupling between Ni and Cu. Moreover, the addition of the conductive material acetylene black (AB) could immensely increase the electric conductivity of AlNiCu-MOG, leading to its improved MOR activity with a peak current density of 33.24 mA cm−2. These results represent an important first step towards the application of MOGs in the MOR.

Searching for non-noble metal catalysts with high activities and low price is critical to the commercialization of methanol oxidation in the process of fuel cells. Herein, two new pseudo-isomeric Ni metal–organic frameworks (Ni-MOFs) (CTGU-17/CTGU-18) have been prepared with 1,4-naphthalenedi-carboxylate (H2NDC), 4,4′-dipyridyl amine (DPA) and Ni(ClO4)2 under hydrothermal condition. Each phase contains one water molecule, but differs dramatically in its bonding to the framework, resulting in different topological networks with fourfold interpenetrating 4-connected dia net (CTGU-17) and (3,7)-connected net (CTGU-18) and diverse electrocatalytic performance for methanol oxidation reaction (MOR). Remarkably, by combining each MOF with the conductive additive, acetylene black (AB), a composite material, AB&CTGU-18(2:4) was confirmed to have an excellent performance for MOR with a high mass specific peak current of 442.3 mA·mg−1. The enhanced electrocatalytic activities and robustness might be attributed to the synergetic effect of acetylene black and the active metal centers of MOFs particles for methanol oxidation. The present work would provide a new insight for the rational design of MOFs-based composites with enhanced methanol oxidation reaction performance.

Tungsten ditelluride (WTe2) is provoking immense interest because of its unique electronic properties, but studies about its semiconducting hexagonal (2H) phase are quite rare. Herein, we report the synthesis of semiconducting 2H WTe2 nanosheets with large positive magnetoresistance, for the first time, by a simple lithium-intercalation-assisted exfoliation strategy. Systematic characterizations including high-resolution transmission electron microscopy, X-ray diffraction, and Raman and X-ray photoelectron spectroscopies provide clear evidence to distinguish the structure of 2H WTe2 nanosheets from the orthorhombic (Td) phase bulk counterpart. The corresponding electronic phase transition from metal to semiconductor is also confirmed by density of states calculation, optical absorption, and electrical transport property measurements. Besides, the 2H WTe2 nanosheets exhibit large positive magnetoresistance with values of up to 29.5% (10 K) and 16.2% (300 K) at 9 T. Overall, these findings open up a promising avenue into the exploration of WTe2-based materials in the semiconductor field.

Embedding cubane [M4 (OH)4 ] (M=Ni, Co) clusters within the matrix of metal-organic frameworks (MOFs) is a strategy to develop materials with unprecedented synergistic properties. Herein, a new material type based on the pore-space partition of the cubic primitive minimal-surface net (MOF-14-type) has been realized. CTGU-15 made from the [Ni4 (OH)4 ] cluster not only has very high BET surface area (3537 m2 g-1 ), but also exhibits bi-microporous features with well-defined micropores at 0.86 nm and 1.51 nm. Furthermore, CTGU-15 is stable even under high pH (0.1 m KOH), making it well suited for methanol oxidation in basic medium. The optimal hybrid catalyst KB&CTGU-15 (1:2) made from ketjen black (KB) and CTGU-15 exhibits an outstanding performance with a high mass specific peak current of 527 mA mg-1 and excellent peak current density (29.8 mA cm-2 ) at low potential (0.6 V). The isostructural cobalt structure (CTGU-16) has also been synthesized, further expanding the application potential of this material type.

The development of metal–organic frameworks (MOFs)-based composites is a research topic of high importance because these composites have great potential for wide utilization in energy transfer and ...

Exploring high-performance metal-organic frameworks (MOFs) for pseudocapacitors is quite meaningful for energy storage. Herein a bimetal NiCo-MOF with ultrathin thickness was prepared via a simple hydrothermal method, which shows excellent electrochemical performance with specific capacitances of 1945.83 and 1700.40 F/g at current densities of 0.5 and 1 A/g, respectively, while maintaining good stability. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy spectra unravel that the strong coupling between Ni and Co species enhances the valence state of Ni2+ in the ultrathin nanosheets, which facilitates the charge transfer during the electrochemical reaction and results in greatly improved pseudocapacitive reactivity. This work provides guidance on the promising prospect of MOF materials for pseudocapacitor applications.

Extensive attention has been paid to metal-organic frameworks (MOFs) due to their interesting structures and plenty of potential applications in catalysis, chemical sensors, magnetism, drug delivery, gas separation and storage. A variety of synthetic methodologies for the synthesis of multifunctional MOFs with complicated structures and attracting properties (such as solvothermal, hydrothermal, urothermal and ionothermal methods), have been developed. Recently, the surfactant-assisted strategy for the synthesis, adjustment and control of multifunctional MOFs has attracted extensive research interest, because surfactants forcefully determine the dimensions, phases, and morphologies of MOFs materials via acting as emulsifiers, detergents, foaming agents, wetting agents or dispersants. This review offers recent developments and prospects in the surfactants as promising templates in the field of growing MOFs, namely, surfactant-assisted strategy for the synthesis of crystalline MOFs, the separation of the pure single-phase of MOFs, the control of the pore’s sizes and morphologies of MOFs (such as core/shell, nanodisks, nanoplates, nanorods, nanosheets) as well as their mechanism.

Developing high-efficiency and cost-effective electrocatalytic oxygen evolution reaction (OER) catalysts would determine the future distributions of energy conversion technologies. Metal-organic frameworks (MOFs), with unsaturated active metal sites, functionalized organic linkers, and large surface areas, are emerging heterogeneous electrocatalysts for the water oxidation process. Herein, we report an oxygen-evolving microporous (3,10)-connected Co6-based MOF (denoted as CTGU-14) for the electrocatalytic OER. Moreover, the integration of Co-MOF and SnO2, SnO2 (15%) & CTGU-14 composite attains remarkable electrochemical OER performance with a small Tafel slope of 68 mV·dec-1, a positive overpotential of 388 mV at 10 mA·cm-2, and overall durability in an alkali medium. The superior OER activities might be ascribed to more convenient electron transfer from the SnO2 additive to the electrode medium, effective surface area and unsaturated active cobalt centers, and more beneficial delivery for hydroxy radicals in the microporous Co-MOF skeleton in the process of the OER.

The integration of heterometallic units and nanostructures into metal-organic frameworks (MOFs) used for the oxygen evolution reaction (OER) can enhance the electrocatalytic performance and help elucidate underlying mechanisms. We have synthesized a series of stable MOFs (CTGU-10a1-d1) based on trinuclear metal carboxylate clusters and a hexadentate carboxylate ligand with a (6,6)-connected nia net. We also present a strategy to synthesize hierarchical bimetallic MOF nanostructures (CTGU-10a2-d2). Among these, CTGU-10c2 is the best material for the OER, with an overpotential of 240 mV at a current density of 10 mA cm-2 and a Tafel slope of 58 mV dec-1 . This is superior to RuO2 and confirms CTGU-10c2 as one of the few known high-performing pure-phase MOF-OER electrocatalysts. Notably, bimetallic CTGU-10b2 and c2 show an improved OER activity over monometallic CTGU-10a2 and d2. Both DFT and experiments show that the remarkable OER performance of CTGU-10c2 is due to the presence of unsaturated metal sites, a hierarchical nanobelt architecture, and the Ni-Co coupling effect.

The development of efficient MOF-based electrocatalysts with good stability to produce hydrogen is a great challenge in the field of sustainable energy conversion. Herein, we introduced a controlled in-situ sulfurization strategy to generate a highly active and stable hybrid catalyst containing good conductive Fe3S4 ultrasmall nanosheets attached on the surface of 3D MIL-53(Fe) for the hydrogen evolution reaction in acidic solutions.

Two new 2D coordination polymers (CPs), [Co2(HL)(4,4′-bipy)(H2O)]·0.5 (4,4′-bipy)·3H2O (1) and [Ni1.5(H2L)(4,4′-bipy)1.5(H2O)3]·2H2O (2), were prepared by hydrothermal reactions of Co(II)/Ni(II) salt with 3,5-(di(2',5'-dicarboxylphenyl)benozoic acid (H5L) and 4,4′-dipyridyl (4,4′-bipy). Compounds 1 and 2 were assembled to form a 3D framework by hydrogen bonds, 1 shows a binodal (3,6)-connected kgd net with a (43)2(46.66.83) topology, while 2 displays a new (3,4)-connected net topology with a Schlafli symbol of {4.62}2{42.62.82}. Magnetic susceptibility measurements indicate that both 1 and 2 show weak antiferromagnetic interactions between the adjacent Co(II) ions and Ni(II) ions. Moreover, electrocatalytic properties of two compounds for the electrocatalytic oxygen evolution reaction (OER) properties of two compounds were also studied.

Two new 3D isostructural MOFs, [M(ddbp)0.5(4,4′-biby)0.5(H2O)2](M = Co/Ni, H4ddbp = 1, 3-di (3′,5′-dicarboxylphenyl)benzene, 4,4′-biby = 4,4-bipyridine) with four-fold poly-rotaxane-like networks, have been successfully synthesized and characterized. The hydrogen evolution reaction of two complexes has also been investigated. Notably, Co-MOF has better HER performance with a smaller overpotential of 357 mV at 10 mA·cm−2, lower Tafel slope of 107 mV·dec−1.

A new 2D MOF with unique [Co5(μ3-OH)2]8+ subunit, [Co5(μ3-OH)2(bcpt)4(bib)2] (1) (H2bcpt = 3,5-bis(3′-carboxyphenyl)-1,2,4-triazole, bib = 1,4-bis(1-imidazoly)benzene) is prepared, which not only shows weak antiferromagnetic interaction between the adjacent Co(II) ion, but also exhibits efficient electrocatalytic hydrogen evolution reaction by the integration with graphene (Gr).

Designing novel multifunctional rare-earth metal-organic frameworks (MOFs) has attracted intensive attention. In particular, employing such materials for sensing or catalytic reactions is still very challenging. Here, a new 3D porous Eu(iii)-MOF, [Eu(cppa)(OH)]·xS (denoted as CTGU-19, S = solvent molecule, CTGU = China Three Gorges University), was synthesized by using 5-(4-carboxyphenyl)picolinic acid (H2cppa) as an organic ligand, and it shows a 3D (3,12)-connected topological net with the point symbol (420·628·818)(43)4, constructed from cubane-shaped tetranuclear europium building units. Interestingly, CTGU-19 can be used as a highly sensitive luminescent sensor to identify ornidazole (ODZ) and nitrofurantoin (NFT) at different excitation wavelengths. This result represents the first example of a lanthanide-metal-organic-framework (Eu-MOF) that can be employed as a discriminating fluorescent probe to recognize ODZ and NFT at different excitation wavelengths. Furthermore, after loading CTGU-19 with Ag and/or Au nanoparticles, the composites exhibit efficient catalytic performance for reducing 2-/3-/4-nitrophenols (2-/3-/4-NP), in which the unit mass reduction rate constants of Ag0.8Au0.2@CTGU-19 for 2-NP, 3-NP, and 4-NP reach 68.8, 53.80, and 52.34 s-1 g-1, respectively.

Four new isostructural coordination polymers, [M2(μ2-H2O)(DTBC)2] (CTGU- 26(M), M ​= ​Zn, Cd, Co and Ni] have been prepared with a new butterfly-typed nitroheterocyclic 4,6-di- 1H-1,2,4-triazol-1-yi-1,3-benzenedicarboxylic acid(H2DTBC) ligand and metal salts under hydrothermal condition. CTGU-26(Zn) features an unusual 2-nodal (4, 8)-connected scu topological network generated by [Zn2(μ2-H2O)(COO)4] units and DTBC2− anion linkers. Luminescent properties measurements indicate that both CTGU-26(Zn) and CTGU-26(Cd) show intense fluorescence-emission compared with free H2DTBC ligand in solid state. Moreover, the electrocatalytic activities of CTGU-26(Co) and CTGU-26(Ni) towards methanol oxidation reaction (MOR) of two compounds were also investigated. Remarkably, by combining each MOF with the conductive 2,3,6,7,10,11-hexahydroxytriphenylene(HHTP) additive, a composite material, HHTP/CTGU-26(Ni)–I was confirmed to have an excellent performance for MOR with a high mass specific peak current of 25.55 ​mA ​cm−2.

The exploration of high-efficiency electrocatalysts for hydrogen evolution reaction (HER) still remains a tremendous challenge for energy conversion. Herein, a composite made from acetylene black (AB) and Cu-based metal-organic frameworks (Cu.BTC) via two different strategies shows distinctly electrocatalytic HER performance. The distinctive design of Cu.BTC incorporated AB exhibits high-efficiency HER activity with a smaller overpotential of 208 mV at −10 mA cm−2, lower Tafel slope of 80 mV·dec−1 and long-term stability of at least 18 h. This work may provide a new strategy for the preparation of conductive MOFs-composite materials.

Reaction of Tb3+ ions with p-terphenyl-3,3″,5,5″-tetracarboxylic acid (H4ptptc) in a mixed solvent system has afforded a new metal-organic framework formulated as [Tb2(ptptc)1.5(H2O)2]n (1). Compound 1 displays a 3D (5,6,8)-connected framework with fascinating one-dimensional triangle open channels. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive response to Fe3+ in DMF solution and biological system through luminescence quenching effects. In addition, 1 also shows high detection for the Cr2O72-, making it a promising dual functional materials for detecting Fe3+ cation and Cr2O72- anion with high sensitivity and selectivity.

It is essential to develop new effective sensor materials for the detection of antibiotics and organic explosives, due to their negative impacts on ecosystems and human health. In this work, guided by an in situ metal‐node metathesis approach, a fluorescent metal–organic gel [MOG(Eu) gel] has been synthesized for the first time by metal‐ion exchange between Eu3+ and Al3+ in the nonfluorescent MOG(Al) gel. More importantly, the postsynthetic MOG(Eu) xerogel shows remarkable selective detection ability towards ronidazole (RDZ), ornidazole (ODZ), metronidazole (MDZ), and dimetridazole (DTZ) antibiotics, as well as 4‐nitrophenol (4‐NP), with low detection limits of 1.205, 0.542, 0.999, 0.377, and 1.582 ppm, respectively. The high quenching efficiencies can be attributed to the decrease of effective energy transfer in the host–guest systems. The strategy of metathesis opens up new opportunities for synthetic methods and functional applications in MOGs materials. MOE (Min. of Education, S’pore)

Metal–organic frameworks (MOFs) incorporating different metal nanoparticles or conductive additives are expected to possess desirable catalytic performance. Herein, we report a novel 3D microporous Co(II)-MOF, [Co1.5(TTAB)0.5(4,4′-bipy)(H2O)] (denoted CTGU-9), based on 3,4,5-tricarboxylic-(3′,4′,5′-tricarboxylazophenyl)benzene (H6TTAB) and 4,4′-bipyridine (4,4′-bipy) ligands. To improve electrical conductivity, a series of composites was integrated by the assembly of CTGU-9 and acetylene black (AB), and shows distinct electrocatalytic activity for the hydrogen evolution reaction (HER). Strikingly, the AB&CTGU-9 (3 : 4) composite exhibits superior HER performance with a very favorable onset potential of 98 mV, an overpotential of 128 mV at 10 mA cm−2, a small Tafel slope of 87 mV dec−1 and long-term stability of at least 21 h. These results indicate that the integration of MOFs with conductive cocatalysts could produce an effective candidate electrocatalyst for HER. Additionally, the gas sorption behavior for N2, CO2, and CH4 is also investigated.

Detecting formaldehyde at low operating temperature and maintaining long-term stability are of great significance. In this work, a hierarchical Co3O4 nanostructure has been fabricated by calcining Co5-based metal–organic framework (MOF) microcrystals. Co3O4-350 particles were used for efficient gas-sensing for the detecting of formaldehyde vapor at lower working temperature (170 °C), low detection limit of 10 ppm, and long-term stability (30 days), which not only is the optimal value among all reported pure Co3O4 sensing materials for the detection of formaldehyde but also is superior to that of majority of Co3O4-based composites. Such extraordinarily efficient properties might be resulted from hierarchically structures, larger surface area and unique pore structure. This strategy is further confirmed that MOFs, especially Co-clusters MOFs, could be used as precursor to synthesize 3D nanostructure metal oxide materials with high-performance, which possess high porosity and more active sites and shorter io...

A new 3D anionic metal-organic framework material, namely, [Me2NH2]2[Cd3(L)]·2H2O (1, H4L ​= ​2,5′-di(3′,5′-dicarboxylphenyl)pyridine) has been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, PXRD, thermogravimetric analysis and proton conduction investigation. In 1, the adjacent Cd(II) ions are joined to form a trinuclear [Cd3(COO)8] secondary building unit (SBU) by eight bridging carboxylate groups of L4− ligands. The trinuclear [Cd3(COO)8] SBUs are connected by L4− ligands into a 3D (4,8)-connected framework with 1D channels. Most interestingly, due to the guest [Me2NH2]+ cations, water molecules and carboxylates sites are lined the pore channels, 1 possesses a remarkable proton conductivity of 1.12 ​× ​10−1 ​S ​cm−1 ​at 60 ​°C and 98% RH, which is comparable to commercially available Nafion. The mechanism of proton conduction was also well discussed.

In this work, we reported a facile, scalable and, environmentally friendly approach to encapsulate catalytically active Ag nanoparticles (NPs) in porous metal–organic gel (MOG) via in situ grown. Attributing to the porous and abundant coordination cites in structural features of the MOG, Ag NPs can be readily fixed in the MOG with a uniform distribution. The resultant Ag NPs@MOG hybrid exhibited a remarkable and durable activity for the catalytic reduction of nitrophenol to aminophenol compounds in an aqueous solution. The strategy for preparing hybrid based on MOGs opens a way toward the functional applications of MOGs.

Three new copper(II)-based coordination polymers, namely [Cu5(μ3-OH)4 (STP)2(4,4’-bipy)2(H2O)2]·4H2O (CTGU-20), [Cu2(μ2-OH)(SIP)(1,4′-bib)2] (CTGU-21) and [Cu2 (SIP)(4,4′-bibp)2(HCOO)]·3H2O(CTGU-22), (STP ​= ​2-sulfoterephthalate, SIP ​= ​5-sulfoisophthalate, 4,4’-bipy ​= ​4,4’-bipyridine, 4,4′-bibp ​= ​4,4’-bis(imidazolyl)biphenyl and 1,4′-bib ​= ​1,4-bis(1-imidazoly) benzene) have been prepared by two less-developed isomeric sulfo-functionalized phthalate ligands under solvothermal conditions and characterized by PXRD, single crystal X-ray diffraction analysis and thermogravimetric analysis.CTGU-20 exhibits a 3D pillared-layer framework constructed from a unique 1D Cu4O8–CuO4 rod packing unit generated by four μ3-OH groups and pyridyl/carboxylicate mixed linkers. While, CTGU-21 shows a 3D pillared-layer framework extended by Cu2(μ2-OH)(SIP) layers and 1,4′-bib pillars. When 1,4′-bib was replaced by longer 4,4′-bibp, CTGU-22 is obtained, which features a 2D bilayer structure bridged by double 4,4′-bibp ligand. Remarkably, complexes CTGU-20, CTGU-21 and CTGU-22 show promising photocatalytic activities toward the degradation of Rhodamine B(RhB), methyl blue(MB) and 9,10-bis (phenylethynyl)anthracene(BPEA). Moreover, the proton conductivity for three complexes were also studied.