High-Valence Metal Doping Induced Lattice Expansion for M-FeNi LDH toward Enhanced Urea Oxidation Electrocatalytic Activities.

The precise design of low-cost, efficient, and definite electrocatalysts is the key to sustainable renewable energy. The urea oxidation reaction (UOR) offers a promising alternative to the oxygen evolution reaction for energy-saving hydrogen generation. In this study, by tuning the lattice expansion, a series of M-FeNi layered double hydroxides (M-FeNi LDHs, M: Mo, Mn, V) with excellent UOR performance are synthesized. The hydrolytic transformation of Fe-MIL-88A is assisted by urea, Ni2+ and high-valence metals, to form a hollow M-FeNi LDH. Owing to the large atomic radius of the high-valence metal, lattice expansion is induced, and the electronic structure of the FeNi-LDH is regulated. Doping with high-valence metal is more favorable for the formation of the high-valence active species, NiOOH, for the UOR. Moreover, the hollow spindle structure promoted mass transport. Thus, the optimal Mo-FeNi LDH showed outstanding UOR electrocatalytic activity, with 1.32 V at 10 mA cm-2 . Remarkably, the Pt/C||Mo-FeNi LDH catalyst required a cell voltage of 1.38 V at 10 mA·cm-2 in urea-assisted water electrolysis. This study suggests a new direction for constructing nanostructures and modulating electronic structures, which is expected to ultimately lead to the development of a class of auxiliary electrocatalysts.

Substituent Engineering in Pore-Space-Partitioned Metal-Organic Frameworks for CO2 Selective Adsorption and Fixation.

Comprehensive understanding of substituent groups located on the pore surface of metal-organic frameworks (which we call substituent engineering herein) can help to promote gas adsorption and catalytic performance through ligand functionalization. In this work, pore-space-partitioned metal-organic frameworks (PSP MOFs) were selected as a platform to evaluate the effect of organic functional groups on CO2 adsorption, separation, and catalytic conversion. Twelve partitioned acs metal-organic frameworks (pacs-MOFs, named SNNU-25-Rn here) containing different functional groups were synthesized, which can be classified into electron-donor groups (-OH, -NH2, -CH3, and -OCH3) and electron-acceptor groups (-NO2, -F, -Cl, and -Br). The experimental results showed that SNNU-25-Rn with electron donors usually perform better than those with electron acceptors for the comprehensive utilization of CO2. The CO2 uptake of the 12 SNNU-25-Rn MOFs ranged from 30.9 to 183.6 cm3 g-1 at 273 K and 1 bar, depending on the organic functional groups. In particular, SNNU-25-OH showed the highest CO2 adsorption, SNNU-25-CH3 had the highest IAST of CO2/CH4 (36.1), and SNNU-25-(OH)2 showed the best catalytic activity for the CO2 cycloaddition reaction. The -OH functionalized MOFs with excellent performance may be attributed to the Lewis acid-base and hydrogen-bonding interactions between -OH groups and the CO2 molecules. This work modulated the effect of the microenvironment of MOFs on CO2 adsorption, separation, and catalysis in terms of substituents, providing valuable information for the precise design of porous MOFs with a comprehensive utilization of CO2.

Au Nanowires Decorated Ultrathin Co3 O4 Nanosheets toward Light-Enhanced Nitrate Electroreduction.

Nitrate is a reasonable alternative instead of nitrogen for ammonia production due to the low bond energy, large water-solubility, and high chemical polarity for good absorption. Nitrate electroreduction reaction (NO3 RR) is an effective and green strategy for both nitrate treatment and ammonia production. As an electrochemical reaction, the NO3 RR requires an efficient electrocatalyst for achieving high activity and selectivity. Inspired by the enhancement effect of heterostructure on electrocatalysis, Au nanowires decorated ultrathin Co3 O4 nanosheets (Co3 O4 -NS/Au-NWs) nanohybrids are proposed for improving the efficiency of nitrate-to-ammonia electroreduction. Theoretical calculation reveals that Au heteroatoms can effectively adjust the electron structure of Co active centers and reduce the energy barrier of the determining step (*NO → *NOH) during NO3 RR. As the result, the Co3 O4 -NS/Au-NWs nanohybrids achieve an outstanding catalytic performance with high yield rate (2.661 mg h-1 mgcat -1 ) toward nitrate-to-ammonia. Importantly, the Co3 O4 -NS/Au-NWs nanohybrids show an obviously plasmon-promoted activity for NO3 RR due to the localized surface plasmon resonance (LSPR) property of Au-NWs, which can achieve an enhanced NH3 yield rate of 4.045 mg h-1 mgcat -1 . This study reveals the structure-activity relationship of heterostructure and LSPR-promotion effect toward NO3 RR, which provide an efficient nitrate-to-ammonia reduction with high efficiency.

Monodispersed Pt Sites Supported on NiFe-LDH from Synchronous Anchoring and Reduction for High Efficiency Overall Water Splitting.

Precise design of low-cost, efficient and definite electrocatalysts is the key to sustainable renewable energy. Herein, this work develops a targeted-anchored and subsequent spontaneous-redox strategy to synthesize nickel-iron layered double hydroxide (LDH) nanosheets anchored with monodispersed platinum (Pt) sites (Pt@LDH). Intermediate metal-organic frameworks (MOF)/LDH heterostructure not only provides numerous confine points to guarantee the stability of Pt sites, but also excites the spontaneous reduction for PtII . Electronic structure, charge transfer ability and reaction kinetics of Pt@LDH can be effectively facilitated by the monodispersed Pt moieties. As a result, the optimized Pt@LDH that with the 5% ultra-low content Pt exhibits the significant increment in electrochemical water splitting performance in alkaline media, which only afford low overpotentials of 58 mV at 10 mA cm-2 for hydrogen evolution reaction (HER) and 239 mV at 10 mA cm-2 for oxygen evolution reaction (OER), respectively. In a real device, Pt@LDH can drive an overall water-splitting at low cell voltage of 1.49 V at 10 mA cm-2 , which can be superior to most reported similar LDH-based catalysts. Moreover, the versatility of the method is extended to other MOF precursors and noble metals for the design of ultrathin LDH supported monodispersed noble metal electrocatalysts promoting research interest in material design.

Oxygen-Vacancy-Rich Cu2O Hollow Nanocubes for Nitrate Electroreduction Reaction to Ammonia in a Neutral Electrolyte.

The electrocatalytic nitrate reduction reaction (NO3--ERR) to ammonia (NH3) is a promising strategy for NH3 production. Cu-based nanomaterials have been regarded as a kind of effective NO3--ERR catalysts. In this work, high-quality hollow Cu2O nanocubes (Cu2O h-NCs) are facilely synthesized by a simple one-step reduction method. The as-prepared Cu2O h-NCs reveal high selectivity and activity for NO3--ERR, which is ascribed to abundant oxygen vacancies, high surface area, hollow architecture, low mass transfer resistance, and strong adsorbing ability toward NO3-. In fact, Cu2O h-NCs can achieve a Faradic efficiency of 92.9% and an NH3 yield of 56.2 mg h-1 mgcat-1 for NH3 production at -0.85 V (vs RHE) potential, which exceeds those of other transition-metal-based NO3--ERR electrocatalysts.

Iron-Doped Cobalt Phosphide Nanohoops for Electroreduction of Nitrate to Ammonia.

Heteroatom doping can effectively tune the electronic structure of an electrocatalyst to accelerate the adsorption/desorption of reaction intermediates, which sharply increases their intrinsic electroactivity. Herein, we successfully prepare iron (Fe)-doped cobalt phosphide (CoP) nanohoops (Fe/CoP NHs) with different Fe/Co atomic ratios as highly active electrocatalysts for the nitrate electrocatalytic reduction reaction (NIT-ERR). Electrochemical measurements reveal that appropriate Fe doping can improve the electroactivity of cobalt phosphide nanohoops for the NIT-ERR. In a 1 M KOH electrolyte, the Fe/CoP NHs with the optimized chemical composition can achieve an efficient ammonia (NH3) generation rate of 27.6 mg h-1 mgcat-1 for the conversion of NO3- into NH3 and a Faradaic efficiency of 93.3% at a -0.25 V potential, which exceed the values of various previously reported nanomaterials in an alkaline electrolyte.

Micropore Regulation in Ultrastable [Sc3O]-Organic Frameworks for Acetylene Storage and Purification.

High storage capacity, high separation selectivity, and high structure stability are essential for an idea gas adsorbent. However, it is not easy to achieve all three at the same time, even for the promising metal-organic framework (MOF) adsorbents. We demonstrate herein that robust [Sc3O]-organic frameworks could be regulated by a micropore combination strategy for high-performance acetylene adsorption. Under the same solvent system with formic acid as a modulator, similar tritopic ligands extend [Sc3O(COO)6] trigonal-prismatic clusters to generate SNNU-5-Sc and SNNU-150-Sc adsorbents. Notably, the two Sc-MOFs can keep their architectures over 24 h in water at different pH values (2-12) or at 90 °C. Modulated by the linker symmetry, the final stacking metal-organic polyhedral cages produce open window sizes of about 10 Å for SNNU-5-Sc and 5 Å + 7 Å for SNNU-150-Sc. Due to such micropore combinations, SNNU-5-Sc exhibits a top-level C2H2 uptake of 211.2 cm3 g-1 (1 atm and 273 K) and SNNU-150-Sc shows high C2H2/CH4, C2H2/C2H4, and C2H2/CO2 selectivities of 80.65, 4.03, and 8.19, respectively, under ambient conditions. Dynamic breakthrough curves obtained on a fixed-bed column and grand canonical Monte Carlo (GCMC) simulations further support their prominent acetylene storage and purification performance. High framework stability, storage capacity, and separation selectivity make SNNU-5-Sc and SNNU-150-Sc ideal acetylene adsorbents in practical applications.

Competitive Coordination-Oriented Monodispersed Ruthenium Sites in Conductive MOF/LDH Hetero-Nanotree Catalysts for Efficient Overall Water Splitting in Alkaline Media.

Rational exploration of efficient, inexpensive, and robust electrocatalysts is critical for the efficient water splitting. Conjugated conductive metal-organic frameworks (cMOFs) with multicomponent layered double hydroxides (LDHs) to construct bifunctional heterostructure catalysts are considered as an efficient but complicated strategy. Here, the fabrication of a cMOF/LDH hetero-nanotree array catalyst (CoNiRu-NT) coupled with monodispersed ruthenium (Ru) sites via a controllable grafted-growth strategy is reported. Rich-amino hexaiminotriphenylene linkers coordinate with the LDH nanotrunk to form cMOF nanobranches, providing numerous anchoring sites to precisely confine and stabilize RuN4 sites. Moreover, monodispersed and reduced Ru moieties facilitate H2 O adsorption and dissociation, and the heterointerface between the cMOF and the LDH further modifies the chemical and electronic structures. Optimized CoNiRu-NT displays a significant increase in electrochemical water-splitting properties in alkaline media, affording low overpotentials of 22 mV at 10 mA cm-2 and 255 mV at 20 mA cm-2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively. In an actual electrochemical system, CoNiRu-NT drives an overall water splitting at a low cell voltage of 1.47 V to reach 10 mA cm-2 . This performance is comparable to that of pure noble-metal-based materials and superior to most reported MOF-based catalysts.

Amide-Functionalized Metal-Organic Frameworks Coupled with Open Fe/Sc Sites for Efficient Acetylene Purification.

Acetylene (C2H2) purification is of great importance for many chemical synthesis and processes. Metal-organic frameworks (MOFs) are widely used for gas adsorption and separation due to their variable structure and porosity. However, the exploitation of ideal MOF adsorbents for C2H2 keeps a challenging task. Herein, a combination of open metal sites (OMSs) and Lewis basic sites (LBSs) in robust MOFs is demonstrated to effectively promote the C2H2 purification performance. Accordingly, SNNU-37(Fe/Sc), two isostructural MOFs constituted by [Fe3O(COO)6] or [Sc3O(COO)6] trinuclear clusters and amide-functionalized tricarboxylate linkers, were designed with extra-stable 3,6-connected new architectures. Derived from the coexistence of high-density OMSs and LBSs, the C2H2 adsorption amounts of SNNU-37(Fe/Sc) are much higher than those values for C2H4 and CO2. Theoretical IAST selectivity values of SNNU-37(Fe) are 2.4 for C2H2/C2H4 (50/50, v/v) and 9.9 for C2H2/CO2 (50/50, v/v) at 298 K and 1 bar, indicating an excellent C2H2 separation ability. Experimental breakthrough curves also revealed that SNNU-37(Fe) could effectively separate C2H2/C2H4 and C2H2/CO2 under ambient conditions. GCMC simulations further indicate that open Fe or Sc sites and amide groups mainly contribute to stronger adsorption sites for C2H2 molecules.

Cobalt phosphide nanorings towards efficient electrocatalytic nitrate reduction to ammonia.

High-quality CoP nanorings (CoP NRs) are easily achieved using a phosphorating treatment of CoOOH nanorings, and reveal high activity towards the hydrogen evolution reaction and the nitrate electrocatalytic reduction reaction due to substantial coordinately unsaturated active sites, a high surface area, and available mass transfer pathways. Consequently, the CoP NRs can achieve a faradaic efficiency of 97.1% towards NO3--to-NH3 conversion and provide an NH3 yield of 30.1 mg h-1 mg-1cat at a -0.5 V potential.

Efficient Nitrate-to-Ammonia Electroreduction at Cobalt Phosphide Nanoshuttles.

The nitrate electroreduction reaction (NO3--ERR) is an efficient and green approach for nitrate remediation, which requires a highly active and selective electrocatalyst. In this work, porous and amorphous cobalt phosphide nanoshuttles (CoP PANSs) are successfully synthesized by using Mg2+ ion-doped calcium carbonate nanoshuttles (Mg-CaCO3 NSs) as the initial reaction precursor via precipitation transformation and a high-temperature phosphidation strategy. Various physical characterizations show that CoP PANSs have porous architecture, amorphous crystal structure, and big surface area. Electrochemical measurements reveal for the first time that CoP PANSs have outstanding electroactivity for NO3--ERR in a neutral electrolyte. At an applied potential of -0.5 V vs reversible hydrogen electrode, CoP PANSs can achieve a high Faraday efficiency (94.24 ± 2.8%) and high yield rate (19.28 ± 0.53 mg h-1 mgcat-1) for ammonia production, which exceeds most reported values at various electrocatalysts for NO3--ERR. Thus, the present result indicates that cobalt phosphide nanomaterials have promising application for NO3--ERR.

Ultrahigh-Uptake Capacity-Enabled Gas Separation and Fruit Preservation by a New Single-Walled Nickel-Organic Framework.

High gas-uptake capacity is desirable for many reasons such as gas storage and sequestration. Moreover, ultrahigh capacity can enable a practical separation process by mitigating the selectivity factor that sometimes compromises separation efficiency. Herein, a single-walled nickel-organic framework with an exceptionally high gas capture capability is reported. For example, C2H4 and C2H6 uptake capacities are at record-setting levels of 224 and 289 cm3 g-1 at 273 K and 1 bar (169 and 110 cm3 g-1 at 298 K and 1 bar), respectively. Such ultrahigh capacities for both gases give rise to an excellent separation performance, as shown for C2H6/C2H4 with breakthrough times of 100, 60 and 30 min at 273, 283 and 298 K and under 1 atm. This new material is also shown to readily remove ethylene released from fruits, and once again, its ultrahigh capacity plays a key role in the extraordinary length of time achieved in the preservation of the fruit freshness.

Precise Pore Space Partitions Combined with High-Density Hydrogen-Bonding Acceptors within Metal-Organic Frameworks for Highly Efficient Acetylene Storage and Separation.

The high storage capacity versus high selectivity trade-off barrier presents a daunting challenge to practical application as an acetylene (C2 H2 ) adsorbent. A structure-performance relationship screening for sixty-two high-performance metal-organic framework adsorbents reveals that a moderate pore size distribution around 5.0-7.5 Šis critical to fulfill this task. A precise pore space partition approach was involved to partition 1D hexagonal channels of typical MIL-88 architecture into finite segments with pore sizes varying from 4.5 Š(SNNU-26) to 6.4 Š(SNNU-27), 7.1 Š(SNNU-28), and 8.1 Š(SNNU-29). Coupled with bare tetrazole N sites (6 or 12 bare N sites within one cage) as high-density H-bonding acceptors for C2 H2 , the target MOFs offer a good combination of high C2 H2 /CO2 adsorption selectivity and high C2 H2 uptake capacity in addition to good stability. The optimized SNNU-27-Fe material demonstrates a C2 H2 uptake of 182.4 cm3 g-1 and an extraordinary C2 H2 /CO2 dynamic breakthrough time up to 91 min g-1 under ambient conditions.

Hydrogen and Potassium Acetate Co-Production from Electrochemical Reforming of Ethanol at Ultrathin Cobalt Sulfide Nanosheets on Nickel Foam.

The sluggish reaction kinetics of the anodic oxygen evolution reaction increases the energy consumption of the overall water electrolysis for high-purity hydrogen generation. In this work, ultrathin cobalt sulfide nanosheets (Co3S4-NSs) on nickel foam (Ni-F) nanohybrids (termed as Co3S4-NSs/Ni-F) are synthesized using cyanogel hydrolysis and a sulfurization two-step approach. Physical characterizations reveal that Co3S4-NSs with a 1.7 nm thickness have abundant holes, implying the big surface area, abundant active edge atoms, and sufficient active sites. Electrochemical measurements show that as-synthesized Co3S4-NSs/Ni-F have excellent electrocatalytic activity and selectivity for ethanol oxidation reaction and hydrogen evolution reaction. Due to their bifunctional property of Co3S4-NSs/Ni-F nanohybrids, a symmetric Co3S4-NSs/Ni-F∥Co3S4-NSs/Ni-F ethanol electrolyzer can be effectively constructed, which only requires a 1.48 V electrolysis voltage to reach a current density of 10 mA cm-2 for high-purity hydrogen generation at the cathode as well as value-added potassium acetate generation at the anode, much lower than the electrolysis voltage of traditional electrochemical water splitting (1.64 V).

The safety and effectiveness of heated humidified high-flow nasal cannula as an initial ventilation method in the treatment of neonatal respiratory distress syndrome: A protocol for systematic review and meta-analysis.

BACKGROUND: This study uses a method of systematic evaluation to evaluate the safety and effectiveness of heated humidified high-flow nasal cannula (HHHFNC) as an initial ventilation method in the treatment of neonatal respiratory distress syndrome (NRDS) scientifically. In the field of evidence-based medicine, this study provides a theoretical reference and basis for choosing appropriate initial non-invasive ventilation methods in the treatment of NRDS, thereby providing assistance for clinical treatment. METHODS: The main electronic network databases were searched by computer, including 4 Chinese databases: CNKI, WangFang Data, CQVIP, SinoMed and 3 English databases: PubMed, The Cochrane Library and EMBASE, the time range of retrieval from the beginning of each database to September 1, 2020. The content involves all the published randomized controlled trials on the effectiveness of HHHFNC compared with NCPAP as an initial ventilation method in the treatment of NRDS. Using a search method that combines medical subject words and free words. Based on the Cochrane risk bias assessment tool, 2 researchers independently screen the literature, and then extract the data we needed in the literature, and cross-check. If it is difficult to decide whether to include literature, then turning to a third researcher for help and making a final decision after discussion, and using RevMan 5.3 and STATA 13.0 to analyze the relative data. RESULTS: Based on the method of meta-analysis, this study analyzes the pre-determined outcome indicators through scientific statistical analysis, and compares the effectiveness and safety of HHHFNC compared with NCPAP as an initial ventilation method in the treatment of NRDS. All results will be published in peer-reviewed high-quality professional academic journals. CONCLUSION: Based on evidence-based medicine, this study will obtain the establishing evidence of comparison that the clinical effectiveness and safety of HHHFNC compared with NCPAP as an initial ventilation method in the treatment of NRDS through the existing data and data, which provides the evidence support of evidence-based medicine in the treatment of NRDS. OSF REGISTRATION NUMBER: September 17, 2020. osf.io/f6at4 (https://osf.io/f6at4).

Tuning the Pore Surface of an Ultramicroporous Framework for Enhanced Methane and Acetylene Purification Performance.

Both methane (CH4) and acetylene (C2H2) are important energy source and raw chemicals in many industrial processes. The development of an energy-efficient and environmentally friendly separation and purification strategy for CH4 and C2H2 is necessary. Ultramicroporous metal-organic framework (MOF) materials have shown great success in the separation and purification of small-molecule gases. Herein, the synergy effect of tritopic polytetrazolate and ditopic terephthalate ligands successfully generates a series of isoreticular ultramicroporous cadmium tetrazolate-carboxylate MOF materials (SNNU-13-16) with excellent CH4 and C2H2 purification performance. Except for the uncoordinated tetrazolate N atoms serving as Lewis base sites, the pore size and pore surface of MOFs are systematically engineered by regulating dicarboxylic acid ligands varying from OH-BDC (SNNU-13) to Br-BDC (SNNU-14) to NH2-BDC (SNNU-15) to 1,4-NDC (SNNU-16). Benefiting from the ultramicroporous character (3.8-5.9 Å), rich Lewis base N sites, and tunable pore environments, all of these ultramicroporous MOFs exhibit a prominent separation capacity for carbon dioxide (CO2) or C2 hydrocarbons from CH4 and C2H2. Remarkably, SNNU-16 built by 1,4-NDC shows the highest ideal adsorbed solution theory CO2/CH4, ethylene (C2H4)/CH4, and C2H2/CH4 separation selectivity values, which are higher than those of most famous MOFs with or without open metal sites. Dynamic breakthrough experiments show that SNNU-16 can also efficiently separate the C2H2/CO2 mixtures with a gas flow rate of 4 mL min-1 under 1 bar and 298 K. The breakthrough time (18 min g-1) surpasses most best-gas-separation MOFs and nearly all other metal azolate-carboxylate MOF materials under the same conditions. The above prominently CH4 and C2H2 purification abilities of SNNU-13-16 materials were further confirmed by the Grand Canonical Monte Carlo (GCMC) simulations.

Tailoring the Pore Environment of a Robust Ga-MOF by Deformed [Ga3O(COO)6] Cluster for Boosting C2H2 Uptake and Separation.

The construction of superstable metal-organic frameworks (MOFs) for selective gas uptake is urgently demanded but remains a great challenge. Herein, a unique bifunctional deformed [Ga3O(COO)6] inorganic secondary building unit (SBU) generated from the desymmetrical evolution of typical triangular prismatic trinuclear cluster was first introduced, which was extended by an isosceles triangular organic linker to produce a robust Ga-MOF (SNNU-63). Remarkably, SNNU-63 can stabilize in water at 25 °C for 96 h and at 80 °C for more than 24 h, which surpasses nearly all other Ga-MOFs. The combined effects of open metal sites and hydrophobic pore environment provided by deformed [Ga3O] SBUs render SNNU-63 with high C2H2 storage capacity and efficient C2H2 and natural gas purification performance. The ideal adsorbed solution theory calculation, column breakthrough tests, and grand canonical Monte Carlo simulations demonstrate that SNNU-63 is a potential material for addressing the challenge of C2H2/CO2 and C2H2/CH4 mixture separation under ambient conditions.

Multimetal Incorporation into 2D Conductive Metal-Organic Framework Nanowires Enabling Excellent Electrocatalytic Oxidation of Benzylamine to Benzonitrile.

As an important organic intermediate, benzonitrile (BN) is widely involved in organic synthetic chemistry and pharmaceutical and dyestuff industries. However, the exploration of a more efficient and controllable synthesis technique and the corresponding greener catalysts for the synthesis of BN still poses a great challenge. Herein, with multimetallic two-dimensional conductive metal-organic frameworks (2D cMOF) as anodic electrocatalysts, we develop a green, convenient, and highly efficient electrochemical synthesis strategy for BN. Thanks to the intrinsic 2D electrically conductive structure and the optimized the multimetallic coupling catalytic effect, the resulting multimetallic 2D cMOFs exhibit excellent benzylamine (BA) electrooxidation performance. Especially, the trimetallic 2D cMOF (NiCoFe-CAT) requires an ultralow potential of 1.29 V vs reversible hydrogen electrode (RHE) to achieve a 10 mA·cm-2 current density, which indicates the fastest reaction and the most favorable thermodynamic condition. A very high yield (0.058 mmol·mg-1·h-1) and faradic efficiency (∼87%) of benzonitrile are both achieved during the BA electrooxidation reaction at 1.45 V. The reaction mechanism investigations indicated that the various redox mediators of MII/MIII (Ni, Co, Fe) may be regarded as multimetal active species to promote BA conversion. Also, the excellent cycling durability of multimetallic 2D cMOFs further promotes their potential practical applications. These electrocatalytic performances are considered excellent and nearly surpass all other reported Ni-based inorganics or MOF-based electrocatalysts for the electrocatalytic oxidation of benzylamine.

Systematic Regulation of C2H2/CO2 Separation by 3p-Block Open Metal Sites in a Robust Metal-Organic Framework Platform.

The separation of a mixture of C2H2 and CO2 is a great challenge due to their similar molecular sizes and shapes. Al-based metal-organic frameworks (Al-MOFs) have great promise for gas separation applications due to their light weight, high stability, and low cost. However, the cultivation of suitable Al-MOF single crystals is extremely difficult and has limited their explorations up to now. Since In, Ga, and Al are all 3p-block metal elements, a systematic application of the periodic law to investigate 3p-MOFs will undoubtedly help in the understanding and development of worthy Al-MOF materials. Herein, we report the design of a robust 3p metal-organic framework platform (SNNU-150) and the systematic regulation of C2H2/CO2 separation by open 3p-block metal sites. X-ray single-crystal diffraction analysis reveals that SNNU-150 is a 3,6-connected 3D framework consisting of [M3O(COO)6] trinuclear secondary building units (SBUs) and tritopic nitrilotribenzoate (NTB) linkers. Small {[M3O(COO)6]4(NTB)6} tetrahedral cages and extra-large {[M3O(COO)6]10(NTB)14} polyhedral cages connect with each other to generate a hierarchically porous architecture. These 3p-MOFs present very high water, thermal, and chemical stability, especially for SNNU-150-Al, which can maintain its framework at 85 °C in water for 24 h and in a room-temperature environment for more than 30 days. IAST calculations, breakthrough experiments, and GCMC simulations all show that SNNU-150 MOFs have top-level C2H2/CO2 separation performance and follow the order Al-MOF > Ga-MOF > In-MOF.

Mimic of Ferroalloy To Develop a Bifunctional Fe-Organic Framework Platform for Enhanced Gas Sorption and Efficient Oxygen Evolution Electrocatalysis.

It is well-known that the formation of ferroalloy with the addition of the second or third metal during the steel-making process usually can improve the performance of the iron. Inspired by ferroalloy materials, it is speculated that the pore environment, framework charge, and catalytic properties of metal-organic frameworks (MOFs) could be optimized dramatically via the introduction of ferroalloy-like inorganic building blocks. However, different to ferroalloy, the accurate integration of different metals into one MOF platform is still challenging. Herein, taking advantages of the good compatibility for metals in trigonal prismatic trinuclear cluster, a series of Fe-based alloy-like [M3O(O2C)6] motifs (M3 = Fe3, Fe1.5Ni1.5, Fe1.5Co1.5, Fe1.5Ti1.5, FeCoNi, and FeTiCo) are successfully generated, which further lead to a robust Fe-MOF material family (SNNU-5s). These multicomponent MOFs not only provide a good chance to explore the impact of pore environment on gas adsorption/separation but also offer an opportunity to the efficient electrocatalytic reaction directly. Accordingly, compared with the SNNU-5-Fe parent structure, the pore characters of heterometallic SNNU-5 MOFs are clearly regulated by the type of alloy-like building blocks. SNNU-5-FeTi displays more superior gas separation performance for CO2/CH4, C2H2/CH4, C2H4/CH4, and C2H2/CO2 gas mixtures. What is more, benefited from the multimetallic active sites and their catalytic synergy, FeCoNi-ternary alloy-like cluster-based SNNU-5 MOF material exhibits an exceptional oxygen evolution reaction activity in aqueous solution at pH = 13, which delivers a low overpotential (ηj=10 = 317 mV), a fast reaction kinetics (Tafel slope = 37 mV dec-1), and excellent catalytic stability. This facile multialloy-like building block strategy holds promise to accurately design and improve the performance of MOFs, as well as open an avenue to understand the related mechanisms.