The conjugation of metal–organic frameworks (MOFs) into different multicomponent materials to precisely construct aligned heterostructures is fascinating but elusive owing to the disparate ...interfacial energy and nucleation kinetics. Herein, a promising lattice‐matching growth strategy is demonstrated for conductive MOF/layered double hydroxide (cMOF/LDH) heteronanotube arrays with highly ordered hierarchical porous structures enabling an ultraefficient oxygen evolution reaction (OER). CoNiFe‐LDH nanowires are used as interior template to engineer an interface by inlaying cMOF and matching two crystal lattice systems, thus conducting a graft growth of cMOF/LDH heterostructures along the LDH nanowire. A class of hierarchical porous cMOF/LDH heteronanotube arrays is produced through continuously regulating the transformation degree. The synergistic effects of the cMOF and LDH components significantly promote the chemical and electronic structures of the heteronanotube arrays and their electroactive surface area. Optimized heteronanotube arrays exhibit extraordinary OER activity with ultralow overpotentials of 216 and 227 mV to deliver current densities of 50 and 100 mA cm−2 with a small Tafel slope of 34.1 mV dec−1, ranking it among the best MOF and non‐noble‐metal‐based catalysts for OER. The robust performance under high current density and vigorous gas bubble conditions enable such hierarchical MOF/LDH heteronanotube arrays as promising materials for practical water electrolysis.
Porous metal–organic framework/layered double hydroxide (MOF/LDH) hierarchical heteronanotube arrays consisting of a lattice‐matched 2D conductive MOF and a trimetallic LDH, established by an inner template sacrificial process, enable excellent activity and superior stability toward the oxygen evolution reaction (OER) reaction in comparison to the best MOF and non‐noble‐metal‐based catalysts for the OER.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The design of highly efficient, stable, and noble‐metal‐free bifunctional electrocatalysts for overall water splitting is critical but challenging. Herein, a facile and controllable synthesis ...strategy for nickel–cobalt bimetal phosphide nanotubes as highly efficient electrocatalysts for overall water splitting via low‐temperature phosphorization from a bimetallic metal‐organic framework (MOF‐74) precursor is reported. By optimizing the molar ratio of Co/Ni atoms in MOF‐74, a series of CoxNiyP catalysts are synthesized, and the obtained Co4Ni1P has a rare form of nanotubes that possess similar morphology to the MOF precursor and exhibit perfect dispersal of the active sites. The nanotubes show remarkable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic performance in an alkaline electrolyte, affording a current density of 10 mA cm−2 at overpotentials of 129 mV for HER and 245 mV for OER, respectively. An electrolyzer with Co4Ni1P nanotubes as both the cathode and anode catalyst in alkaline solutions achieves a current density of 10 mA cm−2 at a voltage of 1.59 V, which is comparable to the integrated Pt/C and RuO2 counterparts and ranks among the best of the metal‐phosphide electrocatalysts reported to date.
An unusual nanotube of nickel–cobalt bimetal phosphides is produced via a facile and controllable low‐temperature phosphorization from a bimetallic metal‐organic framework (MOF‐74) by optimizing the molar ratio of Co/Ni atoms in MOF precursor. It shows remarkable hydrogen evolution reaction and oxygen evolution reaction catalytic performance in an alkaline electrolyte and can be used as a highly efficient electrocatalyst for overall water splitting.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A UiO type MOF with Lewis basic bipyridyl sites was synthesized and structurally characterized. After being activated by Soxhlet-extraction, this MOF exhibits high storage capacities for H2, CH4 and ...CO2, and shows unusual stepwise adsorption for liquid CO2 and solvents, indicating a sequential filling mechanism on different adsorption sites.
Due to their significance in energy-conversion applications, the development of efficient non-noble electrocatalysts for the oxygen reduction reaction (ORR) to accelerate the sluggish cathodic ...reaction for fuel cells and metal-air batteries has attracted extensive attention. Metal-organic frameworks (MOF), a family of crystalline organic-inorganic porous materials constituted by ligands and metal struts, have been identified as a promising platform for preparing efficient ORR catalysts. In this review, the progress and current developments of MOF derivatives as non-noble ORR catalysts are summarized. Beginning with an introduction of the general principles in fabricating efficient non-noble ORR catalysts, the MOF-directed synthesis in the fabrication of non-noble catalysts with finely controlled local electronic structures, extrinsic structures and interface properties is reviewed and discussed. The construction of special local electronic structures and morphologies under the guidelines of general principles is presented in detail. Particularly, the superiority of MOFs, as compared to other precursors, in the controlled immobilization of favourable factors into resulting catalysts is highlighted. Finally, prospects and future perspectives of MOF utilization in fabricating non-noble ORR catalysts are proposed.
This review provides an overview of crucial roles that MOFs have played in constructing non-noble ORR catalysts.
The separation of acetylene and carbon dioxide is an essential but challenging process owing to the similar molecular sizes and physical properties of the two gas molecules. Notably, these molecules ...usually exhibit different orientations in the pore channel. We report an adsorption site selective occupation strategy by taking advantage of differences in orientation to sieve the C2H2 from CO2 in a judiciously designed amine‐functionalized metal–organic framework, termed CPL‐1‐NH2. In this material, the incorporation of amino groups not only occupies the adsorption sites of CO2 molecules and shields the interaction of uncoordinated oxygen atom and CO2 molecules resulting in a negligible adsorption amount and a decrease in enthalpy of adsorption but also strengthened the binding affinity toward C2H2 molecules. This material thus shows an extremely high amount of C2H2 at low pressure and a remarkably high C2H2/CO2 IAST selectivity (119) at 1 bar and 298 K.
Metal–organic framework (CPL‐1‐NH2) with keyhole‐like pore apertures offers selective adsorption site properties for gas separation. Amine groups limit interactions with CO2 molecules by decreasing the enthalpy of CO2 adsorption, whereas the binding affinity of C2H2 is increased (see picture, distances in Å). CPL‐1‐NH2 demonstrates a remarkably high C2H2 selectivity with C2H2/CO2 (50/50) mixtures at 1 bar and 298 K.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Highlights
An electrochemical-induced surface restructuring strategy is developed to design phosphorus-doped carbon@MoP electrocatalysts which exhibits excellent activity for the hydrogen evolution ...reaction (HER) in both acidic and alkaline electrolytes.
The activation process and the fundamental mechanism of the prominent synergistic interaction between the phosphorus-doped carbon and MoP are elucidated.
The hydrogen evolution reaction (HER) through electrocatalysis is promising for the production of clean hydrogen fuel. However, designing the structure of catalysts, controlling their electronic properties, and manipulating their catalytic sites are a significant challenge in this field. Here, we propose an electrochemical surface restructuring strategy to design synergistically interactive phosphorus-doped carbon@MoP electrocatalysts for the HER. A simple electrochemical cycling method is developed to tune the thickness of the carbon layers that cover on MoP core, which significantly influences HER performance. Experimental investigations and theoretical calculations indicate that the inactive surface carbon layers can be removed through electrochemical cycling, leading to a close bond between the MoP and a few layers of coated graphene. The electrons donated by the MoP core enhance the adhesion and electronegativity of the carbon layers; the negatively charged carbon layers act as an active surface. The electrochemically induced optimization of the surface/interface electronic structures in the electrocatalysts significantly promotes the HER. Using this strategy endows the catalyst with excellent activity in terms of the HER in both acidic and alkaline environments (current density of 10 mA cm
−2
at low overpotentials, of 68 mV in 0.5 M H
2
SO
4
and 67 mV in 1.0 M KOH).
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Metal selenides with good electronic conductivity and high theoretical capacities are regarded as potential anodes for potassium-ion batteries (PIBs). But the large radius and heavy weight of K-ion, ...and inefficient electrolyte lead to sluggish reaction kinetics and structure collapse of the electrode. Herein, the enhanced rate capability and cycling performance of FeSe/C nanocomposites are achieved by electrolyte salt and solvent engineering. The introduction of KFSI-EC/DEC electrolyte significantly boosts the charge transfer, K-ion diffusion, and capacitive behavior of FeSe/C electrode, which can be attributed to the stable solvation structure and the inorganic compound-rich solid electrolyte interphase layer demonstrated by computational studies on molecular orbital energy levels, X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) characterizations. Consequently, the FeSe/C electrode shows superior rate performance (230 mA h g−1 at 10 A g−1) and stable cycling performance (550 mA h g−1 at 0.2 A g−1 over 100 cycles). Additionally, ex-situ X-ray diffraction, HRTEM and XPS characterizations throw light on the reversible conversion reaction mechanism between FeSe and K-ion.
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•FeSe/C nanocomposites are prepared by direct selenization of Fe-MOF.•Enhanced performance is achieved by the regulation of potassium salt and solvent.•FeSe/C nanocomposites deliver 550 mA h g−1 over 100 cycles at 0.2 A g−1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Understanding the crystallization pathway is of fundamental importance in controlling structures and functionalities for metal–organic frameworks (MOFs), but only few studies have been reported on ...the mechanism of crystallization for MOFs to date. Here, by using a microdroplet flow (MF) reaction technique, we successfully revealed the different status of HKUST-1 during its crystal growth process. The morphologies and structures of crystals at different stages were recorded and characterized by scanning electron microscopy, transmission electron microscopy, and small-angle X-ray diffraction. Experimental observations clearly demonstrate a process of crystallization by particle attachment (CPA) for crystal growth of HKUST-1 under MF conditions. The superstructure of HKUST-1, which is assembled from oriented attachment of nanosized particles of HKUST-1, is observed at early stage of crystal growth. This type of superstructure gradually transforms to true single crystals through a ripening effect upon increasing residence time, accompanied by increase in dimensions of crystals. Thus, the superstructure is the intermediate state during crystallization and acts as the bridge between disordered reactants and highly ordered single crystals. Based on these findings, the crystal growth of HKUST-1 in MF reaction can be elucidated as a process involving three steps: the generation of nanosized primary particles, the following assembly of the primary particles into a superstructure, and the ripening of superstructure into a crystal. Furthermore, the superstructure of HKUST-1 shows superior performance for CO2 and CH4 adsorptions. The CPA mechanism in the crystallization of HKUST-1 demonstrated in this work is in clear contrast to the monomer-by-monomer addition mechanism in classic models of crystal growth. This mechanism could have important reference meaning for understanding the crystal growth mechanism of other type of MOFs or other special morphologies.
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IJS, KILJ, NUK, PNG, UL, UM
MnO nanorods encapsulated by N-doped carbon are prepared, using polypyrrole-coated MnOOH nanorods as both a template and a precursor. The resulting coaxial nanorods have a one-dimensional shape, ...nanoscale size and an N-doped carbon coating within one particle, which substantially improves their electrochemical performance. As an anode material for lithium-ion batteries, the coaxial nanorods of MnO/N-doped carbon deliver a specific capacity of 982 mA h g super(-1) at a current density of 500 mA g super(-1) after 100 cycles, higher than the values for pure MnO nanostructures and MnO/C nanocomposites. At a current density of 5000 mA g super(-1), the reversible capacity of the coaxial nanorods could be as high as 372 mA h g super(-1).
Contrast-enhanced ultrasound (CEUS) and elastography are of great value in the diagnosis of cervical cancer (CC). However, there is limited research on the role of contrast-enhanced ultrasound ...combined with elastography in predicting concurrent chemoradiotherapy and disease progression for cervical cancer. The purpose of this study was to evaluate the feasibility of contrast-enhanced ultrasound combined with elastography and tumor prognosis.
MRI was performed on 98 patients with cervical cancer before and after treatment. Before, during, and 1 week after the treatment, contrast-enhanced ultrasound and elastography were conducted, and the alterations of ultrasound-related parameters at each time point of the treatment were compared. The correlation between contrast-enhanced ultrasound combined with elastic imaging and oncological outcome was assessed.
There was no notable difference in overall clinical data between the complete remission (CR) group and the partial remission (PR) group (P>0.05). Before treatment, there were no statistically significant differences in elasticity score, time to peak (TTP), and peak intensity (PI) between the CR group and the PR group. However, there were no statistical differences in elastic strain ratio (SR) and area under the curve (AUC) before and after treatment between the CR group and the PR group, and there were also no statistical differences in the elastic strain ratio (SR) and area under the curve (AUC) of contrast-enhanced ultrasound parameters between the CR group and the PR group before and during treatment. There was a statistically significant difference after treatment (P<0.05).At present, the follow-up of patients is about 1 year, 7 patients were excluded due to loss to follow-up, and 91 patients were included in the follow-up study. Through the review of the cases and combined with MRI (version RECIST1.1) and serology and other related examinations, if the patient has a new lesion or the lesion is larger than before, the tumor marker Squamous cell carcinoma antigen (SCC-Ag) is significantly increased twice in a row, and the patient is divided into progressive disease (PD). Those who did not see significant changes were divided into stable disease (SD) group. The relationship between clinical characteristics, ultrasound parameters and disease progression in 91 patients was compared. There was no significant difference in age and clinical stage between the two groups (P>0.05), but there was a significant difference in the elevation of tumor marker squamous cell carcinoma antigen (SCC-Ag) between the two groups (P<0.05).With the growth of tumors, TTP decreased, elasticity score and PI increased, and the difference was statistically significant (P<0.05). The AUC of SCC-Ag was 0.655, the sensitivity was 85.3%, and the specificity was 45.6%.The AUC, sensitivity and specificity of ultrasound parameters combined with SCC-Ag predicted disease progression was 0.959, 91.2% and 94.8%.
Using contrast-enhanced ultrasound and elastography to predict the efficacy and disease progression of concurrent chemoradiotherapy is feasible. In addition, the combination of SCC-Ag with contrast-enhanced ultrasound and elastography can further enhance the efficiency of predicting disease progression.
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