The design and development of crystalline porous materials (CPMs), including metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs), have been subjects of extensive study due to their ...regular crystalline lattices and well-defined pore structures. In recent times, an enormous amount of research effort has gone into using CPMs as sacrificial templates to fabricate electrochemically functional materials. The inherently electrochemically active sites inside CPMs are notably abundant and being explored with respect to electrochemical reactions. In this review, electrochemically active sites and the space around them (metal ions, ligands, crystal structures, pores, and morphologies) inside CPMs are the focus and recent progress in the fields of metal-ion batteries, metal-air batteries, water splitting, and other related electrochemical devices has been summarized. Overall, this review provides guidance on the preparation of electroactive CPMs
via
rational design and modulation of active sites such as redox-active metal clusters and organic ligands, and the space around the electrochemically active sites, and their applications in electrochemical energy storage and conversion systems.
This review provides references for the preparation of electroactive CPMs
via
rational design and modulation of active sites and the space around them, and their application in electrochemical energy storage and conversion systems.
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•Co-hydroxyapatite could effectively activate peroxymonosulfate to removal RhB.•Hydroxyl radicals, sulfate radicals and singlet oxygen were responsible for RhB degradation.•Singlet ...oxygen played a leading role in RhB degradation.•Surface hydroxyl groups contributed to the co-catalytic activity of PMS activation.
Hydroxyapatite (HAP) is a promising supporter of catalyst due to its potential in immobilizing metals stably. HAP supported cobalt-based catalyst (Co-HAP) was synthesized via a facile ion exchange-calcination method to reduce the Co leaching. The synthesized Co-HAP was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) analysis and X-ray photoelectron spectroscopy (XPS). Cobalt ions were incorporated into HAP structure and Co3O4 on HAP surface. Co-HAP showed satisfactory performance in peroxymonosulfate (PMS) activation for eliminating Rhodamine B (RhB) in aqueous solution. Co-HAP even revealed a better activity than that of CoFe2O4. •OH, SO4•- and 1O2 were all involved in RhB degradation and 1O2 played a leading role. High content of surface oxygen groups could be found on Co-HAP after RhB degradation, which might be resulted from the high amounts of hydroxyl groups. The presence of hydroxyl groups performed the co-catalytic activity of PMS activation in Co-HAP/PMS system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Piezo-catalysis was first used to degrade a nondye pollutant, 4-chlorophenol (4-CP). In this process, hydrothermally synthesized tetragonal BaTiO3 nano/micrometer-sized particles were used as the ...piezo-catalyst, and the ultrasonic irradiation with low frequency was selected as the vibration energy to cause the deformation of tetragonal BaTiO3. It was found that the piezoelectric potential from the deformation could not only successfully degrade 4-chlorophenol but also effectively dechlorinate it at the same time, and five kinds of dechlorinated intermediates, hydroquinone, benzoquinone, phenol, cyclohexanone, and cyclohexanol, were determined. This is the first sample of piezo-dechlorination. Although various active species, including h+, e–, •H, •OH, •O2 –, 1O2, and H2O2, were generated in the piezoelectric process, it was confirmed by ESR, scavenger studies, and LC-MS that the degradation and dechlorination were mainly attributed to •OH radicals. These •OH radicals were chiefly derived from the electron reduction of O2, partly from the hole oxidation of H2O. These results indicated that the piezo-catalysis was an emerging and effective advanced oxidation technology for degradation and dechlorination of organic pollutants.
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IJS, KILJ, NUK, PNG, UL, UM
Preparation of hierarchical carbon nanomaterials from metal−organicframeworks (MOFs) offers immense potential in the improvement of energy density, tunability, and stability of functional materials ...for energy storage and conversion. How interconnected nitrogen (N)‐doped wrinkled carbon foils derived from MOF nanosheets can serve as high‐performance sodium storage materials due to their multiscale porous structure is shown here. The novel N‐doped carbon nanomaterials are synthesized through the pyrolysis of 2D Mn‐based MOFs, which are produced through the assistance of monodentate ligands to enable the planar growth of MOFs. Subsequent acid etching creates hierarchical pores and channels to allow rapid ion transport. The resulting materials achieve high‐rate capability (165 and 150 mA h g−1 at current densities of 8 and 10 A g−1, respectively) and high stability (capacity retention 72.8% after 1000 cycling at 1.0 A g−1), when they are used as anode in sodium‐ion capacitors.
Interconnected nitrogen‐doped wrinkled carbon foils are successfully synthesized from MOF nanosheets. The unique N‐doping species and favorable pores in the as‐designed materials synergistically contribute to the significantly improved performance in sodium storage.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A cost-efficient and stable oxygen evolution electrocatalyst is essential for improving energy storage and conversion efficiencies. Herein, 2D nanosheets with randomly cross-linked CoNi layered ...double hydroxide （LDH） and small CoO nanocrystals were designed and synthesized via in situ reduction and interface- directed assembly in air. The formation of CoNi LDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal-oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O 2p orbitals, and electron transfer between metal atoms through Ni-O-Co, a number of Co and Ni atoms in the CoNi LDH present a high ＋3 valency. These unique characteristics result in a high density of oxygen evolution reaction （OER） active sites, improving the affinity between OH- and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER. The CoNi LDH/CoO featured a low onset potential of 1.48 V in alkaline medium, and required an overpotential of only 300 mV at a current density of 10 mA.cm-2, while displaying good stability in accelerated durability tests.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Discharging phosphorus (P)-contaminated water directly into the aquatic environment leads to resource loss and eutrophication. Thus, removing P from waste streams is imperative. In this study, ...calcium-decorated biochar (Ca-BC) in different mass ratios of Ca to BC was designed to effectively adsorb P from solution. Ca-BC was characterized through X-ray diffraction (XRD) analysis, followed by isotherm and kinetic adsorption experiments. The decorated Ca on the BC surface was found to have preferred P adsorption ability. A design of calcium hydroxide (Ca(OH)2) to flour in a mass ratio of 2:1 was found to have a maximum adsorption capacity of 314.22 mg g−1 for P. The Langmuir and pseudo-second-order models fit the sorption process adequately. XRD analysis indicated that the preferable adsorption ability to P was due to the reaction of Ca(OH)2 and PO43−, forming the hydroxylapatite (Ca5(PO4)3(OH)) crystal. The P in solution was transformed to the crystal. Thus, Ca-BC is an environmental friendly and low-cost sorbent for P removal.
•Ca-decorated biochar was synthesized.•Excellent sorption capacity of 314.22 mg g−1 for P was observed.•Langmuir and pseudo-second-order models fit the sorption process adequately.•Formation of Ca5(PO4)3(OH) crystal contributes to P sorption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
With the wide application of nuclear energy and the rapid development of mining, a great quantity of uranium (U(VI)) containing wastewater is inevitably generated. In this work, a facile ...environmental-friendly coprecipitation method was proposed for the green synthesis of binary layered double hydroxides (Ni–Co LDHW-7), which could be used to efficiently adsorb U(VI) from wastewater. Pseudo-second-order kinetic model and Dubinin-Radushkevich model fitted well with the adsorption of U(VI) on Ni–Co LDHW-7, the maximum adsorption capacity of U(VI) on Ni–Co LDHW-7 was 201.09 mg/g calculated by the Langmuir model. Adsorption equilibrium reached after 30 min, which is a spontaneous and endothermic process. Fourier Transform Infrared Spectrometer (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurements manifested that the favorable U(VI) extraction on Ni–Co LDHW-7 is mainly ascribed to inner-layer surface electrostatic interaction and complexation, which is dominated by abundant oxygen-containing M-OH and interlayer OH− ions. Briefly, this work provides a facial and environmental-friendly Ni–Co LDHW-7 for removing U(VI) in actual uranium-containing wastewater.
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•A facile environmental-friendly coprecipitation method was proposed for green synthesis of Ni–Co LDHW-7.•Adsorption capacity of uranium reached 201.09 mg/g calculated by Langmuir model at pH = 6 and 298 K.•Metal hydroxyl group configuration and the hydroxyl groups contributed to U(VI) binding on Ni–Co LDHW-7.•Ni–Co LDHW-7 showed good stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Carboxylic acid-based metal-organic frameworks (MOFs) are normally passed for the “pre-catalysts” for oxygen evolution reaction (OER) due to the hydroxides constructed
in-situ
during its alkaline ...hydrolysis process (AHP) in lye. Whereas, it remains a mystery that they show advantageous activity over prototypical hydroxides when they are directly acted as OER catalysts. Herein, we propose for the first time that the steric hindrance effect of Nafion can induce enhanced catalytic activity of such MOFs. Different from conventional catalysts without AHP, the Nafion with 3D structure weakens the AHP of Co-MOF nanoribbons, thus forming small size and low crystallinity species (cobalt hydroxide) with more active sites. And the existence of Nafion also optimizes its electronic structure, which is confirmed by transmission electron microscopy (TEM),
in-situ
UV absorption spectra,
in-situ
Raman spectroscopy and so on. Compared with Co-MOF-K obtained by directly immersing the Co-MOF nanoribbons in 1.0 M KOH, the Co-MOF-NK obtained by AHP of Co-MOF mixed with Nafion shows better catalytic activity. Based on the above inspiration, we realized the low overpotential of 268 mV at 10 mA·cm
−2
by preparing CoFe-MOF-NK. This work provides a new understanding of the structural reconstruction of MOFs in the field of electrocatalysis.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Enzymeless hydrogen peroxide （H2O2） detection with high sensitivity and excellent selectivity is desirable for clinical diagnosis. Herein, one-dimensional Co3O4 nanowires have been successfully ...constructed on reduced graphene oxide （rGO） via a simple hydrothermal procedure and subsequent thermal treatment. These Co3O4 nanowires, assembled by small nanoparticles, are interlaced with one another and make a spider web-like structure on rGO. The formation of Co3O4-rGO hybrids is attributed to the structure-directing and anchoring roles of DDA and GO, respectively. The resulting structure possesses abundant active sites, the oriented transmission of electrons, and unimpeded pathways for matter diffusion, which endows the Co3O4-rGO hybrids with excellent electrocatalytic performance. As a result, the obtained Co3O4-rGO hybrids can serve as an efficient electrochemical catalyst for H2O2 oxidation and high sensitivity detection. Under physiological conditions, the oxidation current of H2O2 varies linearly with respect to its concentration from 0.015 to 0.675 mM with a sensitivity of 1.14 mA.mM^-1.cm^-2 and a low detection limit of 2.4 μM. Furthermore, the low potential （-0.19 V） and the good selectivity make Co3O4-rGO hybrids suitable for monitoring H2O2 generated by liver cancer HepG2 cells. Therefore, it is promising as a non-enzymatic sensor to achieve real-time quantitative detection of H2O2 in biological applications.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
