Cooperative defect engineering and ligand modification in UiO-66 to achieve high proton conductivity.

D-UiO-66-NIM with high proton conductivity has been synthesized through the dual strategy of defect engineering and ligand modification. Moreover, D-UiO-66-NIM exhibits good temperature cycling stability and durability in proton conductivity. This work has developed a new method to obtain efficient MOF-based proton conductors.

Multiflower-like ReS2/NiAl-LDH Heterojunction for Visible-Light-Driven Photocatalytic CO2 Reduction.

The development of high-efficiency heterojunction photocatalysts has been recognized as an effective approach to facilitate photocatalytic CO2 reduction. In this research, we successfully synthesized a novel multiflower-like ReS2/NiAl-LDH heterojunction through a hydrothermal method. Remarkably, when exposed to visible-light irradiation, 2-ReS2/NiAl-LDH demonstrated an exceptional CO production rate of 272.26 µmol·g-1·h-1, which was 4.0 and 10.8 times higher than that of pristine NiAl-LDH and ReS2. The intertwined structure of ReS2 and NiAl-LDH promoted the efficient transfer and separation of photogenerated carriers, thereby significantly enhancing the photocatalytic CO2 reduction capabilities of the ReS2/NiAl-LDH. Furthermore, the carrier transfer pathway for the 2-ReS2/NiAl-LDH heterojunction was elucidated, suggesting a type II scheme mechanism, as evidenced by photochemical deposition experiments. The findings of this study offer valuable insights and pave the way for future research in the design and construction of LDH-based and ReS2-based heterojunctions for efficient photocatalytic CO2 reduction.

Achieving High Proton Conductivity in MIL-91(Al) Aerogel.

The processability and sustainability of proton conductors are two important indicators of their application. Here, MIL-91(Al) with an intrinsic proton conduction framework originating from protonated phosphonate groups was cross-linked with poly(vinyl alcohol) (PVA) to obtain MIL-91(Al) aerogel through freeze-drying. This simple and inexpensive strategy not only facilitated the processing of MIL-91(Al) powder but also resulted in a molded MIL-91(Al) aerogel having a high proton conductivity of 1.02 × 10-2 S cm-1 at 70 °C and 100% relative humidity. Furthermore, MIL-91(Al) aerogel was recyclable and reusable, in line with the principles of environmental protection and sustainability. To the best of our knowledge, this is the first example of using a metal-organic framework aerogel as a proton conductor, which may develop a new model system in this field.

Enhancement of CO2 adsorption and separation in basic ionic liquid/ZIF-8 with core-shell structure.

A novel strategy was proposed to improve the performance of gas separation in nano-materials, by fabricating a core-shell structure out of the basic ionic liquid ([Emim]2[IDA]) and zeolitic imidazolate framework (ZIF-8). The [Emim]2[IDA]/ZIF-8 exhibits a remarkable CO2 adsorption capacity of 14 cm3 g-1 at 298 K and 20 kPa, the ideal selectivity of CO2/N2 is as high as 104 and CO2/CH4 is 348 at 298 K and 100 kPa, which are much higher than the CO2 adsorption capacity (4.3 cm3 g-1) and the selectivity (SCO2/N2 = 7.4, SCO2/CH4 = 2.7) of ZIF-8. This work could pave the way for designing advanced nanostructures tailored for gas separation.

Engineering Metallic Alloy Electrode for Robust and Active Water Electrocatalysis with Large Current Density Exceeding 2000 mA cm-2.

The amelioration of brilliantly effective electrocatalysts working at high current density for the oxygen evolution reaction (OER) is imperative for cost-efficient electrochemical hydrogen production. Yet, the kinetically sluggish and unstable catalysts remain elusive to large-scale hydrogen (H2) generation for industrial applications. Herein, a new strategy is demonstrated to significantly enhance the intrinsic activity of Ni1-xFex nanochain arrays through a trace proportion of heteroatom phosphorus doping that permits robust water splitting at an extremely large current density of 1000 and 2000 mA cm-2 for 760 h. The in situ formation of Ni2P and Ni5P4 on Ni1-xFex nanochain arrays surface and hierarchical geometry of the electrode significantly promote the reaction kinetics and OER activity. The OER electrode provides exceptionally low overpotentials of 222 and 327 mV at current densities of 10 and 2000 mA cm-2 in alkaline media, dramatically lower than benchmark IrO2 and is among the most active catalysts yet reported. Remarkably, the alkaline electrolyzer renders a low voltage of 1.75 V at a large current density of 1000 mA cm-2, indicating outperformed overall water splitting. The electrochemical fingerprints demonstrate vital progress toward large-scale H2 production for industrial water electrolysis.

Constructing FeNiPt@C Trifunctional Catalyst by High Spin-Induced Water Oxidation Activity for Zn-Air Battery and Anion Exchange Membrane Water Electrolyzer.

Developing cost-efficient trifunctional catalysts capable of facilitating hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) activity is essential for the progression of energy devices. Engineering these catalysts to optimize their active sites and integrate them into a cohesive system presents a significant challenge. This study introduces a nanoflower (NFs)-like carbon-encapsulated FeNiPt nanoalloy catalyst (FeNiPt@C NFs), synthesized by substituting Co2+ ions with high-spin Fe2+ ions in Hofmann-type metal-organic framework, followed by carbonization and pickling processes. The FeNiPt@C NFs catalyst, characterized by its nitrogen-doped carbon-encapsulated metal alloy structure and phase-segregated FeNiPt alloy with slight surface oxidization, exhibits excellent trifunctional catalytic performance. This is evidenced by its activities in HER (-25 mV at 10 mA cm-2), ORR (half-wave potential of 0.93 V), and OER (294 mV at 10 mA cm-2), with the enhanced water oxidation activity attributed to the high-spin state of the Fe element. Consequently, the Zn-air battery and anion exchange membrane water electrolyzer assembled by FeNiPt@C NFs catalyst demonstrate remarkable power density (168 mW cm-2) and industrial-scale current density (698 mA cm-2 at 1.85 V), respectively. This innovative integration of multifunctional catalytic sites paves the way for the advancement of sustainable energy systems.

Metal-Organic-Framework-Derived Bromine and Nitrogen Dual-Doped Porous Carbon for CO2 Photocycloaddition Reaction.

The cycloaddition of CO2 with epoxides driven by light irradiation is an intriguing approach to preparing cyclic carbonates. However, it remains a great challenge to achieve high photocatalytic efficiency in the absence of a cocatalyst. Herein, we explored a metal-organic-framework (MOF)-templated pyrolysis strategy to prepare uniform bromine ions/nitrogen-codoped carbon materials (Br-CN) as low-cost photocatalysts for CO2 cycloaddition. The optimal catalyst Br-CN-1-550 can be used as a photocatalyst to catalyze CO2 cycloaddition, remarkably reducing the energy consumption. As a result of its benefits of high photothermal efficiency and rich nucleophilic sites (Br ions), BN-CN-1-550 affords a 9 times higher yield of 4-(chloromethyl)-1,3-dioxolan-2-one than that of the ZIF-8-derived CN under cocatalyst-free conditions and light irradiation (300 mW·cm-2 full-spectrum irradiation, 10 h). This strategy provides a cost-effective way to obtain cyclic carbonate under cocatalyst-free conditions.

Construction of Hollow Ultrasmall Co3O4 Nanoparticles Immobilized in BN for CO2 Conversion.

Rational design and fabrication of metal-organic framework-derived metal oxide (MO) materials featuring a hollow structure and active support can significantly enhance their catalytic activity for specific reactions. Herein, a series of Co3O4 nanoparticles (NPs) immobilized in boron nitride (denoted as Co3O4@BN) with highly open and precisely controllable structures were constructed by an in situ self-assembly method combined with a controlled annealing process. The obtained Co3O4@BN not only possesses a hollow structure but also shows highly dispersed Co3O4 NPs and high loadings of up to 34.3 wt %. Owing to the ultrafine particle size and high dispersity, the optimized Co3O4@BN exhibits high catalytic activity for the cycloaddition of CO2 to epoxides under mild conditions (i.e., 100 °C and CO2 balloon), resulting in at least 4.5 times higher yields (99%) of styrene carbonate than that of Co3O4 synthesized by the pristine ZIF-67. This strategy sheds light on the rational design of hollow MO materials for various advanced applications.

Unlocking the Potential of High Entropy Alloys in Electrochemical Water Splitting: A Review.

The global pursuit of sustainable energy is focused on producing hydrogen through electrocatalysis driven by renewable energy. Recently, High entropy alloys (HEAs) have taken the spotlight in electrolysis due to their intriguing cocktail effect, broad design space, customizable electronic structure, and entropy stabilization effect. The tunability and complexity of HEAs allow a diverse range of active sites, optimizing adsorption strength and activity for electrochemical water splitting. This review comprehensively covers contemporary advancements in synthesis technique, design framework, and physio-chemical evaluation approaches for HEA-based electrocatalysts. Additionally, it explores design principles and strategies aimed at optimizing the catalytic activity, stability, and effectiveness of HEAs in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. Through an in-depth investigation of these aspects, the complexity inherent in constituent element interactions, reaction processes, and active sites associated with HEAs is aimed to unravel. Eventually, an outlook regarding challenges and impending difficulties and an outline of the future direction of HEA in electrocatalysis is provided. The thorough knowledge offered in this review will assist in formulating and designing catalysts based on HEAs for the next generation of electrochemistry-related applications.

Amorphous Engineering of Scalable Metal-Organic Framework-Derived Electrocatalyst for Highly Efficient Oxygen Evolution Reaction.

The engineering of amorphous metal-organic frameworks (MOFs) offers potential opportunities for the construction of electrocatalysts for efficient oxygen evolution reaction (OER). Herein, highly efficient OER performance and durability in alkaline electrolyte are discovered for MOF-derived amorphous and porous electrocatalysts, which are synthesized in a brief procedure and can be facilely produced in scalable quantities. The structural inheritance of MOF amorphous catalysts is significant for the retention of catalytic sites and the diffusion of electrolytes, and the presence of Fe sites can change the electronic structure and effectively control the adsorption behavior of important intermediates, accelerating reaction kinetics. The obtained amorphous A-FeNi can be transformed from FeNi-MOF effortlessly and instantly, and it only needs low overpotentials of 152 and 232 mV at 10 and 100 mA cm-2 with a Tafel slope of 17 mV dec-1 in 1 m KOH for OER. Moreover, A-FeNi possesses high corrosion resistance and durability, therefore A-FeNi can work continually for at least 400 h at 100 mA cm-2 . This work may pave a new avenue for the design of MOFs-related amorphous electrocatalyst.

Constructing Nitrogen-Doped Carbon Hierarchy Structure Derived from Metal-Organic Framework as High-Performance ORR Cathode Material for Zn-Air Battery.

The development of efficient and low-cost catalysts for cathodic oxygen reduction reaction (ORR) in Zn-air battery (ZAB) is a key factor in reducing costs and achieving industrialization. Here, a novel segregated CoNiPt alloy embedded in N-doped porous carbon with a nanoflowers (NFs)-like hierarchy structure is synthesized through pyrolyzing Hofmann-type metal-organic frameworks (MOFs). The unique hierarchical NFs structure exposes more active sites and facilitates the transportation of reaction intermediates, thus accelerating the reaction kinetics. Impressively, the resulting 15% CoNiPt@C NFs catalyst exhibits outstanding alkaline ORR activity with a half-wave potential of 0.93 V, and its mass activity is 7.5 times higher than that of commercial Pt/C catalyst, surpassing state-of-the-art noble metal-based catalysts. Furthermore, the assembled CoNiPt@C+RuO2 ZAB demonstrates a maximum power density of 172 mW cm-2 , which is superior to that of commercial Pt/C+RuO2 ZAB. Experimental results reveal that the intrinsic ORR mass activity is attributed to the synergistic interaction between oxygen defects and pyrrolic/graphitic N species, which optimizes the adsorption energy of the intermediate species in the ORR process and greatly enhances catalytic activity. This work provides a practical and feasible strategy for synthesizing cost-effective alkaline ORR catalysts by optimizing the electronic structure of MOF-derived catalysts.

A Cu-Based Metal-Organic Framework Cu-Cip with Cuproptosis for Cancer Therapy and Inhibition of Cancer Cell Migration.

Microflora within cancer cells plays a pivotal role in promoting metastasis of cancer. However, contemporary anticancer research often overlooks the potential benefits of combining anticancer and antibacterial agents. Consequently, a metal-organic framework Cu-Cip with cuproptosis and antibacterial properties was synthesized for cancer therapy. To enhance the anticancer effect of the material, Mn2+ was loaded into Cu-Cip, yielding Mn@Cu-Cip. The fabricated material was characterized using single-crystal X-ray diffraction, PXRD, and FT-IR. By interacting with overexpressed H2O2 to produce ROS and accumulating Cu ions in cancer cells, MOFs exhibited excellent anticancer performance. Moreover, the material displayed the function of damaging Staphylococcus aureus and Escherichia coli, revealing the admirable antibacterial properties of the material. In addition, the antibacterial ability could inhibit tumor cell migration. The Cu-based MOF revealed promising applications in the field of tumor treatment.

Construction of Core-Shell MOF CSMnP with Enzyme-Like Activity for Chemotherapy and Chemodynamic Therapy.

Materials with enzyme-like activity have received a lot of attention in the field of tumor catalytic therapy. Here, biocompatible core-shell MOF CSMnP with two valence states of Mn ion, which could process chemodynamic therapy (CDT), was designed and synthesized. Besides, it could also promote a series of catalytic processes in the tumor microenvironment (TME). CSMnP catalyzed endogenous hydrogen peroxide (H2O2) to oxygen (O2) via catalase-like activity and then combined with the outer layer Mn(II)-PBC to convert O2 into superoxide radicals (•O2-), exhibiting oxidase-like activity. Besides, intracellular glutathione (GSH) could be effectively consumed through the glutathione oxidase-like activity of Mn3+. The occurrence of the cascade reactions effectively amplified the enzymatic production to enhance CDT. Furthermore, the therapeutic effect of CSMnP was improved through the loading of cationic drug DOX. The loading capacity was 11.10 wt %, which was 2.2 times that of Mn(III)-PBC (4.95 wt %), and the release of DOX showed a characteristic response. Therefore, the core-shell MOF with enzyme-like activity had a potential application for tumor combination therapy.

Differential fluorescent response to amino acids based on metal-organic framework Zn-PBC.

A novel metal-organic framework (MOF) Zn-PBC (H2PBC = pyridine-3,5-bis(phenyl-4-carboxylic acid)) was designed and synthesized via a solvothermal reaction with the H2PBC ligand, and produced a strong fluorescence. The material exhibited good stability and an ideal luminescent property in water. In addition, it was found that Zn-PBC displayed a different fluorescent response to different types of amino acids, and the mechanism was investigated. This research might give insight to the interaction between MOFs and amino acids, which would provide a strategy to fabricate MOF-based sensors for biomolecules in future.

Pore Modulation of Hydrogen-Bonded Organic Frameworks for Efficient Separation of Propylene.

Developing hydrogen-bonded organic frameworks (HOFs) that combine functional sites, size control, and storage capability for targeting gas molecule capture is a novel and challenging venture. However, there is a lack of effective strategies to tune the hydrogen-bonded network to achieve high-performance HOFs. Here, a series of HOFs termed as HOF-ZSTU-M (M=1, 2, and 3) with different pore structures are obtained by introducing structure-directing agents (SDAs) into the hydrogen-bonding network of tetrakis (4-carboxyphenyl) porphyrin (TCPP). These HOFs have distinct space configurations with pore channels ranging from discrete to continuous multi-dimensional. Single-crystal X-ray diffraction (SCXRD) analysis reveals a rare diversity of hydrogen-bonding models dominated by SDAs. HOF-ZSTU-2, which forms a strong layered hydrogen-bonding network with ammonium (NH4 + ) through multiple carboxyl groups, has a suitable 1D "pearl-chain" channel for the selective capture of propylene (C3 H6 ). At 298 K and 1 bar, the C3 H6 storage density of HOF-ZSTU-2 reaches 0.6 kg L-1 , representing one of the best C3 H6 storage materials, while offering a propylene/propane (C3 H6 /C3 H8 ) selectivity of 12.2. Theoretical calculations and in situ SCXRD provide a detailed analysis of the binding strength of C3 H6 at different locations in the pearl-chain channel. Dynamic breakthrough tests confirm that HOF-ZSTU-2 can effectively separate C3 H6 from multi-mixtures.

Halogen-modified metal-organic frameworks for efficient separation of alkane from natural gas.

As a rich green energy source, natural gas is widely used in many fields such as the chemical industry, automobile energy, and daily life. However, it is very challenging to separate and recover C2H6 and C3H8 from natural gas. Metal-organic frameworks (MOFs) as an emerging type of multi-pore porous materials show huge potential in gas adsorption separation. Herein, we report pillar-layered MOFs, Ni (BDC)(DABCO)0.5 (DMOF-X), modified by halogen atoms (F, Cl, Br), and investigate their CH4/C2H6/C3H8 separation performance. The experimental results show that DMOF-Cl exhibited a extremely high adsorption capacity for C3H8 and C2H6. Under the conditions of 298 K and 100 kPa, the adsorption capacities for C3H8 and C2H6 on DMOF-Cl are as high as 6.23 and 4.94 mmol g-1, which are superior to the values for most of the porous materials that have been reported. In addition, DMOF-Cl also shows high C3H8/CH4 (5: 85, V/V) and C2H6/CH4 (10: 85, V/V) separation selectivities, with values of 130.9 and 12.5, respectively. Finally, DMOF-Cl also demonstrated great potential as an adsorbent for separating C3H8/C2H6/CH4.

Salt-Assisted Low-Temperature Growth of 2D Bi2 O2 Se with Controlled Thickness for Electronics.

Bi2 O2 Se is the most promising 2D material due to its semiconducting feature and high mobility, making it propitious channel material for high-performance electronics that demands highly crystalline Bi2 O2 Se at low-growth temperature. Here, a low-temperature salt-assisted chemical vapor deposition approach for growing single-domain Bi2 O2 Se on a millimeter scale with thicknesses of multilayer to monolayer is presented. Because of the advantage of thickness-dependent growth, systematical scrutiny of layer-dependent Raman spectroscopy of Bi2 O2 Se from monolayer to bulk is investigated, revealing a redshift of the A1g mode at 162.4 cm-1 . Moreover, the long-term environmental stability of ≈2.4 nm thick Bi2 O2 Se is confirmed after exposing the sample for 1.5 years to air. The backgated field effect transistor (FET) based on a few-layered Bi2 O2 Se flake represents decent carrier mobility (≈287 cm2  V-1 s-1 ) and an ON/OFF ratio of up to 107 . This report indicates a technique to grow large-domain thickness controlled Bi2 O2 Se single crystals for electronics.

Theoretical Investigations on MIL-100(M) (M=Cr, Sc, Fe) with High Adsorption Selectivity for Nitrogen and Carbon Dioxide over Methane.

The removal of impurity gases (N2 , CO2 ) in natural gas is critical to the efficient use of natural gas. In this work, the selective adsorption for N2 and CO2 over CH4 on MIL-100 (M) (M=4 Cr, 10 Cr, 6 Fe, 1 In, 1 Sc, 3 V) is studied by density functional theory (DFT) calculations. The calculated adsorption energy of the large-size cluster model (LC) of MIL-100 (M) shows that the 4 MIL-100 (4 Cr) is the best at the refinement of natural gas due to the lower adsorption energy of CH4 (-2.58 kJ/mol) in comparison with that of N2 (-21.49 kJ/mol) and CO2 (-23.82 kJ/mol). 1 MIL-100 (1 Sc) and 1 MIL-100 (6 Fe) can also achieve selective adsorption and follows the order 4 MIL-100 (4 Cr)>1 MIL-100 (1 Sc)>1 MIL-100 (6 Fe). In the research of the selective adsorption mechanism of MIL-100 (M) (M=4 Cr, 1 Sc, 6 Fe), the independent gradient model (IGM) indicates that these outstanding adsorbents interact with CO2 and N2 mainly through the electrostatic attractive interaction, while the van der Walls interaction dominates in the interaction with CH4. The atomic Projected Density of State (PDOS) further confirms that CH4 contributes least to the intermolecular interaction than that of CO2 and N2 . Through the scrutiny of molecular orbitals, it is found that electrons transfer from the gas molecule to the metal site in the adsorption of CO2 and N2 . Not only does the type of the metallic orbitals, but also the delocalization of the involved orbitals determines the selective adsorption performance of MIL-100. Both Cr and Sc share their d z 2 ${{d}_{{z}^{2}}}$ orbitals with the gases, making 1 MIL-100 (1 Sc) another potential effective separator for CH4 . Additionally, the comparison of adsorption energy and PDOS shows that the introduction of ligands such as benzene impedes the electron donation from gas molecules (CO2 , N2 ) to the metal site, indicating electron-withdrawing ligands will further favor the adsorption.

Pillared-MOF@NiV-LDH Composite as a Remarkable Electrocatalyst for Water Oxidation.

Oxygen evolution reaction (OER) represents a highly important electrochemical transformation in energy storage and conversion technologies. Considering the low rate of this four-electron half-reaction, there is a demand for efficient, stable, and noble-metal-free electrocatalysts to improve the kinetic and economical parameters. In this work, a new pillared-MOF@NiV-LDH nanocomposite based on a CoII metal-organic framework (pillared-MOF) and heterometallic Ni/V-layered double hydroxide (NiV-LDH) was assembled via a simple protocol, characterized, and explored as an electrocatalyst in OER. A remarkable electrocatalytic efficiency of pillared-MOF@NiV-LDH in 1 M KOH is evidenced by a low overpotential (238 mV at 10 mA cm-2 current density) and a small value of the Tafel slope (62 mV dec-1). These parameters are very close to those of the reference IrO2 electrocatalyst and are superior to the majority of the LDH- and MOF-based systems previously applied for OER. Excellent stability of pillared-MOF@NiV-LDH was confirmed by the chronopotentiometry tests for 70 h and linear-sweep voltammetry after 7000 cycles. Features such as rich electroactive sites, porous structure, high surface area, and synergic effect between pillared-MOF and NiV-LDH are likely responsible for the remarkable electrocatalytic efficiency of this electrocatalyst in OER. Despite prior reports on the application of NiV-LDH in OER, the present study describes the first example where this type of LDH is blended with MOF to generate a nanocomposite material. The interface between the two components of the composite can improve the electronic structure and, in turn, the electrocatalytic behavior. The introduction of this composite paves the way toward the synthesis of other multicomponent materials with potential applications in different energy fields.

Multi-Responsive Sensor Based on Porous Hydrogen-Bonded Organic Frameworks for Selective Sensing of Ions and Dopamine Molecules.

Hydrogen-bonded organic frameworks (HOFs), as an emerging porous material, have attracted increasing research interest in fluorescence sensing due to their inherent fluorescence emission units with unique physicochemical properties. Herein, based on the organic building block 3,3',5,5'-tetrakis-(4-carboxyphenyl)-1,1'-biphenyl (H4TCBP), the porous material HOF-TCBP was successfully synthesized using hydrogen bond self-assembly in a DMF solution. The fluorescence properties of the HOF-TCBP solution showed that when the concentration was high, excimers were easily formed, the PL emission was red-shifted, and the fluorescence intensity became weaker. HOF-TCBP showed good sensitivity and selectivity to metal ions Fe3+, Cr3+, and anion Cr2O72-. In addition, HOF-TCBP can serve as a label-free fluorescent sensor material for the sensitive and selective detection of dopamine (DA). HOF-based DA sensing is actually easy, low-cost, simple to operate, and highly selective for many potential interfering substances, and it has been successfully applied to the detection of DA in biological samples with satisfactory recoveries (101.1-104.9%). To our knowledge, this is the first report of HOF materials for efficient detection of the neurotransmitter dopamine in biological fluids. In short, this work widely broadens the application of HOF materials as fluorescent sensors for the sensing of ions and biological disease markers.