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Metal-organic frameworks (MOFs) are promising electrochemical materials that possess large specific surface areas, high porosities, good adjustability, and high activities. However, many conventional MOFs exhibit poor conductivity, which hinders their application in electrochemistry. In recent years, conductive MOFs (cMOFs) have attracted a considerable attention. As an important transition metal hydroxide, Ni(OH)

The invention of printing technologies has revolutionized the manner in which information is transmitted and reproduced. In the modern era, printing technologies , which are equipped with computerized control and design methods, have become considerably efficient and effective, facilitating A significant breakthrough in the manufacture of high-performance electrochemical energy storage systems. Through careful design and execution, the components of energy storage devices, particularly electrodes, can be formulated into functional inks, enabling the use of divers materials and devices in high-performance energy storage applications. This reviewfocuses on three major printing technologies: inkjet printing, screen printing, and 3D printing, introducing the principles of each printing technology, the design and preparation of various electrode inks, and their applications in supercapacitors. Finally, the challenges and scope for the future development of printing technologies forhigh-performance supercapacitors are presented.

Metal organic frameworks (MOFs) have been widely researched and applied in many fields. However, the poor electrical conductivity of many traditional MOFs greatly limits their application in electrochemistry, especially in energy storage. Benefited from the full charge delocalization in the atomical plane, conductive MOFs (c-MOFs) exhibit good electrochemical performance. Besides, unlike graphene, c-MOFs are provided with 1D cylindrical channels, which can facilitate the ion transport and enable high ion conductivity. Transition-metal oxides (TMOs) are promising materials with good electrochemical energy storage performance due to their excellent oxidation-reduction activity. When composited with TMOs, the c-MOFs can significantly improve the capacitance and rate performance. In this work, for the first time, we designed serial MnO2@Ni-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanoarrays with different lengths and explored how the lengths influence the electrochemical energy storage performance. By taking advantage of the high redox activity of MnO2 and the excellent electron and ion conductivity in Ni-HHTP, when assembled as the positive electrode material in an aqueous asymmetric supercapacitor, the device displays high energy density, outstanding rate performance, and superior cycle stability. We believe that the results of this work would provide a good prospect for developing other c-MOF composites as a potential class of electrode materials in energy storage and conversion.

电解水能够为我们提供清洁可持续的能源, 这对生态环境系统大有裨益. 因此, 在电解水体系中, 开发新型有效的析氧催化剂迫在眉睫. 本文首先通过自下而上的方法合成Au@ZIF-67, 再对其进行控温处理得到纳米复合物Au@ZIF-67-500. 通过扫描电子显微镜、透射电子显微镜、X射线光电子能谱和紫外光谱等一系列测试手段揭示了材料的纳米结构形貌及其表面电子分布. 在 1.0 mol L−1 KOH电解液中, 利用三电极体系进行了电催化性能的测试. 结果显示, 该纳米复合物在催化析氧反应过程中呈现出良好的催化活性和较好的稳定性. 这一结果可以归功于三方面的协同作用: 金纳米粒子的包覆、多孔结构和有效的热控制. 这种通过简单方法制备的析氧催化剂对能量转换领域具有一定的借鉴意义.

Uneven energy distribution in space–time has led to an increase in the demand for energy storage devices. In recent years, aqueous energy storage systems have attracted considerable attention because of their low manufacturing costs and superior safety. For next-generation energy storage systems, the cyclic stability of the electrode material and exceptional energy storage performance are necessary. This review briefly summarizes the performance of aqueous electrochemical energy storage devices based on nanodimensions, including aqueous sodium-ion batteries, aqueous aluminum-ion batteries, aqueous zinc-ion batteries, aqueous supercapacitors, and other aqueous electric energy storage systems. Furthermore, to reveal the mechanism of the energy storage performance among various electrode materials with varying dimensions, we highlight the recent significant progress of novel electrode materials based on their rational design, controlled synthesis, and corresponding energy storage performance.

Two dimensional (2D) ultrathin nonprecious metal based catalysts show excellent electrocatalytic activities, due to the larger surface areas, more catalytic sites and more interconnected electron-transfer access than their bulk counterparts. Here, we synthesized cobalt pyrophosphate (Co2P2O7) nanosheets with different thickness by a simple and efficient one-step hydrothermal process. The catalytic performance of the obtained Co2P2O7 was investigated via diverse electrochemical measurement. Due to the unique 2D structure and the flexible coordination of pyrophosphate group, the as-prepared Co2P2O7 catalyst had excellent electrocatalytic performance and good stability, which could rank among the most active nonprecious metal catalysts for oxygen evolution reaction and oxygen reduction reaction. In addition, the ultrathin Co2P2O7 nanosheets exhibited good performance as the air cathode catalyst for zinc air batteries.

By integrating the merits of lanthanide elements and quantum dots, we firstly design CeO2 quantum dots doped Ni-Co hydroxide nanosheet via a controllable synthetic strategy, which exhibits a large specific capacitance (1370.7 F/g at 1.0 A/g) and a good cyclic stability (90.6% retention after 4000 cycles). Moreover, we assemble an aqueous asymmetric supercapacitor with the obtained material, which has an extremely high energy density (108.9 Wh/kg at 378 W/kg) and outstanding cycle stability (retaining 88.1% capacitance at 2.0 A/g after 4000 cycles).

The construction of interpenetrated structures was originally achieved via the self-assembly process by an accidental discovery. Nevertheless, this type of interpenetrated structure exhibits fascinating properties and outstanding applications, such as catalysis, molecule recognition and separation, selective gas adsorption. Recent years, several groups focus on the development of such interesting structures and explore their potential applications in different areas. Herein, interpenetrated structures including interpenetrated supramolecular cages, MOFs and COFs are discussed in this manuscript. Concrete examples in recent years are reviewed to illustrate their synthetic strategies, structural features and potential applications. We would like to provide an overview on the developments in the area of interpenetrated topologies and hope this review can shed some light on the further investigation of interpenetrated architectures and provide some insight on their applications.

Nowadays, materials with a core-shell structure have been widely explored for applications in advanced batteries owing to their superb properties. Core-shell structures based on the electrode type, including anodes and cathodes, and the material compositions of the cores and shells have been summarized. In this review, we focus on core-shell materials for applications in advanced batteries such as LIBs, LSBs and SIBs. Firstly, a novel concept of aggregates of spherical core-shell architectures and their aggregates, linear core-shell architectures and their aggregates, sheet-like core-shell architectures and their aggregates and special core-shell architectures and their aggregates are involved. Secondly, the main material compositions of carbon/Si-based, carbon/metal-based, metal-based materials and organic-based composites are introduced along with the synthesis and electrochemical performances of core-shell nanostructured materials. Finally, the emerging challenges and prospects of core-shell materials are briefly discussed.

Covalent organic frameworks (COFs) are burgeoning crystalline porous materials that are constituted with organic building units and covalent bonds. The pre-designable porous structures make a platform for solving energy and environmental problems. This article systematically presents the basic design principle of COFs and introduces the applications in energy and environment fields, for instance, gas storage, energy storage, photoconduction, and catalysis. We also discussed the gas storage conditions and the strategies to improve the hydrogen storage. Finally, we proposed a scheme for improving the storage capacity of lithium-ion (Li-ion) batteries with COFs and the use of COFs to remove Hg in water, and as a catalyst to make rational use of solar energy.

Core–shell MOF structural materials have become research hotspots in the field of chemical materials in recent decades. This rapidly developing research field has been intensively studied and has attracted great attention. In this review, recent strategies in the synthesis of core–shell MOF structures and their derivatives are summarized, including the in situ method, self-template method, self-assembly method and one-pot method. Regarding the properties of these materials, the core–shell MOF structures and their derivatives possess the features of high specific surface area and ultrahigh porosity; therefore, MOF composite materials show amazing potential in practical applications. In this review, we particularly focus on electrochemical applications such as water splitting reactions, energy storage devices, nanoreactors and sensing equipment. Finally, further developments of core–shell MOF structural composites, future challenges, and promising prospects are proposed.

The Prussian blue analogue (PBA) NiHCF was assembled by carrying out a simple chemical precipitation. Nanocubes of different sizes were prepared by adjusting the concentration during the synthesis process, and a new type of non-enzymatic glucose sensor was constructed. The sensor displayed a good linear response to glucose in the range of 0.5 μM to 2165.5 μM, a detection limit of 0.8621 μM, and a lack of interference by uric acid, ascorbic acid, and other coexisting substances. It provides a new platform for the application of three-dimensional PBA nanomaterial electrodes in medical fields and biological sciences.

Designing nanocomposites with good electrochemical properties is one of the challenges in constructing supercapacitors. Adjustable metal-organic frameworks (MOFs) have potential research value in improving charge storage and transfer due to their multi-porosity. Moreover, MOFs can serve as a precursor to various derivatives. Herein, a series of core-shell structures with macro-microporous ZIF-67 (M-ZIF-67) as the core and layered double hydroxide (LDH) as the shell were synthesized based on polystyrene spheres (PSs) template via a simple ion etching method. As a result, the sample of M-ZIF-67@LDH4 shows a specific capacitance of 597.6 F g-1 at 0.5 A g-1 and a high rate retention of 92% at 3 A g-1 .

Exposing catalytically active metal sites in metal-organic frameworks with maintained porosity could accelerate electron transfer, leading to improved performances in electrochemical energy storage and conversion. Here, we report a series of quasi-ZIF-67 obtained from low temperature calcination of ZIF-67 for electrocatalytic oxygen evolution reaction (OER) and reveal the nanostructural structure via the spherical aberration-corrected transmission electron microscopy. The quasi-ZIF-67-350 not only possesses a large Brunauer-Emmett-Teller surface area of 2038.2 m

As porous materials, metal–organic frameworks (MOFs) have drawn increased attention and are widely applied in various fields such as catalysis, gas/energy storage, chemical sensing, and drug delivery. However, the low conductivity of most MOFs greatly hinders their development. Therefore, the conductive properties of MOFs need to be strategically modulated to achieve optimal performance and realize broad and practical applications. Although most MOFs possess poor conductivity, several sorts of materials in this class exhibit outstanding conductivity and high charge mobility. In this review, the multifarious strategies and recent progress used to improve the electronic and ionic conductivities of MOFs, including the conductive mechanisms and conductivity measurements are summarized and highlighted. In addition, the important breakthroughs, challenges and future trends of MOF-based conductors are also discussed.

Coordination cages with well-defined cavities have attracted sustained attention for their applications in many fields, including host-guest chemistry, molecular recognition, and catalysis, due to their structural aesthetics and unique properties. This review covers the achievements in the catalytic application of these materials in specific chemical transformations. The developments in the utilizations of the coordination cages themselves as catalysts and their abilities to encapsulate catalytic cofactors for catalysis are summarized. In addition, the current challenges and great application potential of coordination cages in catalysis are discussed.

Huynh’s electronic parameter (HEP) was applied to distinguish the electronic properties of benzimidazole and pyrazole donors in N^N ditopic and N^N′ hetero-ditopic, dinucleating ligands by 13C NMR spectroscopy of their dipalladium complexes bearing terminal iPr2-bimy reporter ligands. The 13Ccarbene NMR resonances of the iPr2-bimy ligand (HEPs) indicate stronger donation of the symmetrical dibenzimidazole compared to that of the dipyrazole with a ΔHEP value of 1.54 ppm. Based on this benchmark value, the effect of spacer groups on the electron donation of the mixed benzimidazole-pyrazole ligands was investigated for the first time. The donicity gap between the benzimidazole and pyrazole donors increases with alkylene spacers, but shrinks with the 1,4-phenylene linker, suggesting electronic communication between the two different heterocycles via π-electron conjugation. Furthermore, these complex probes could also be used to catalyze the direct arylation of pentafluorobenzene, which showed that the unsymmetrically bridged, dinuclear complexes with alkylene linkers are more reactive.

Correction for ‘Concentration as a trigger to improve electrocatalytic activity of a Prussian blue analogue in glucose oxidation’ by Zhimin Zhao et al., CrystEngComm, 2019, 21, 5455–5460, DOI: 10.1039/C9CE00947G.

A series of metal-mediated cages, having multiple cavities, was synthesized from PdII cations and tris- or tetrakis-monodentate bridging ligands and characterized by NMR spectroscopy, mass spectrometry, and X-ray methods. The peanut-shaped [Pd3 L1 4 ] cage deriving from the tris-monodentate ligand L1 could be quantitatively converted into its interpenetrated [5Cl@Pd6 L1 8 ] dimer featuring a linear {[Pd-Cl-]5 Pd} stack as an unprecedented structural motif upon addition of chloride anions. Small-angle neutron scattering (SANS) experiments showed that the cigar-shaped assembly with a length of 3.7 nm aggregates into mono-layered discs of 14 nm diameter via solvophobic interactions between the hexyl sidechains. The hepta-cationic [5Cl@Pd6 L1 8 ] cage was found to interact with polyanionic oligonucleotide double-strands under dissolution of the aggregates in water, rendering the compound class interesting for applications based on non-covalent DNA binding.

A donor‐site engineering approach facilitates the formation of heteroleptic [Pd2 L 2 L′2]4+ cage structures through a favored cis‐′in2/out2′ spatial configuration of the methyl groups of 5‐ and 3‐substituted bis‐monodentate picolyl ligands with flat acridone and bent phenothiazine backbones. The heteroleptic cages were confirmed by ESI‐MS and 2D NMR experiments as well as DFT calculations, which pointed toward a cis‐configuration being energetically favored. This was further supported by the synthesis and X‐ray structure of a previously unreported cis‐[Pd(2‐picoline)4]2+ complex. The formation of homoleptic structures, however, was met with considerable steric hindrance at the PdII centers, as observed by the formation of [Pd2 L 3(solvent)2]4+ and [Pd2 L 2(solvent)4]4+ species when only one type of acridone‐based ligand was offered. In contrast, bent phenothiazine ligands with outside‐pointing methyl groups showed the ability to form interpenetrated double‐cages, as revealed by X‐ray crystallography. The general route presented herein enables the assembly of uniform cis‐[Pd2 L 2 L′2]4+ coordination cages, thus furthering the possibility to increase structural and functional complexity in supramolecular systems.

A simple self-assembled [Pd2 L4 ] coordination cage consisting of four carbazole-based ligands was found to dimerize into the interpenetrated double cage [3 X@Pd4 L8 ] upon the addition of 1.5 equivalents of halide anions (X=Cl(-) , Br(-) ). The halide anions serve as templates, as they are sandwiched by four Pd(II) cations and occupy the three pockets of the entangled cage structure. The subsequent addition of larger amounts of the same halide triggers another structural conversion, now yielding a triply catenated link structure in which each Pd(II) node is trans-coordinated by two pyridine donors and two halide ligands. This simple system demonstrates how molecular complexity can increase upon a gradual change of the relative concentrations of reaction partners that are able to serve different structural roles.

Ein einfacher selbstorganisierter [Pd2L4]-Koordinationskafig bestehend aus vier Carbazol-basierten Liganden dimerisiert nach Zugabe von 1.5 Aquivalenten eines Halogenidions (X=Cl−, Br−) zu einem verflochtenen Doppelkafig [3 X@Pd4L8]. Die Halogenidionen agieren als Template, eingelagert in den drei Taschen der verschlungenen Kafigstruktur und umgeben von vier PdII Kationen. Zugabe hoherer Mengen desselben Halogenidions bewirkt eine weitere strukturelle Umwandlung, die in einer dreifach verschlungenen Verbindung resultiert. Letztere enthalt trans-koordinierte PdII-Zentren, die von zwei Pyridin-Donor- und zwei Halogenidliganden umgeben sind. Dieses einfache System zeigt eindrucksvoll, wie molekulare Komplexitat aus der graduellen Anderung der relativen Konzentrationen einer geringen Zahl an Reaktionspartnern erwachsen kann, insbesondere, wenn diese unterschiedliche strukturelle Rollen einnehmen konnen.

Carbon materials derived from metal-organic frameworks (MOFs) have attracted much attention in the field of scientific research in recent years because of their advantages of excellent electron conductivity, high porosity, and diverse applications. Tremendous efforts are devoted to improving their chemical and physical properties, including optimizing the morphology and structure of the carbon materials, compositing them with other materials, and so on. Here, many kinds of carbon materials derived from metal-organic frameworks are introduced with a particular focus on their promising applications in batteries (lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries), supercapacitors (metal oxide/carbon and metal sulfide/carbon), electrocatalytic reactions (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), water treatment (MOF-derived carbon and other techniques), and other possible fields. To close, some existing problem and corresponding possible solutions are proposed based on academic knowledge from the reported literature, along with a great deal of experimental experience.

To improve the efficiency of water electrolysis, developing efficient oxygen evolution reaction (OER) electrocatalysis is extremely important due to its four-electron transfer dynamics. In this work, a π-conjugated molecule (2,3,6,7,10,11-hexahydroxytriphenylene, HHTP), which can accelerate the electron transfer, is coated directly on pristine ZIF-67, resulting in a composite named HHTP@ZIF-67, via a simple one-step solvothermal method. The obtained HHTP@ZIF-67 possesses a Brunauer-Emmett-Teller surface area of 2013.9 m2 g-1 and displays microporous behavior, which can provide enough active sites for OER. The double-layer capacitance of HHTP@ZIF-67 is also enhanced, corresponding to an enlarged electrochemical active surface area. HHTP@ZIF-67 presents a quite low overpotential of 238 mV at 10 mA cm-2 in 1.0 m KOH. This material synthesized via the simple coating strategy is promising in the application of energy conversion devices.

A donor-site engineering approach facilitates the formation of heteroleptic [Pd2 L2 L'2 ]4+ cage structures through a favored cis-'in2 /out2 ' spatial configuration of the methyl groups of 5- and 3-substituted bis-monodentate picolyl ligands with flat acridone and bent phenothiazine backbones. The heteroleptic cages were confirmed by ESI-MS and 2D NMR experiments as well as DFT calculations, which pointed toward a cis-configuration being energetically favored. This was further supported by the synthesis and X-ray structure of a previously unreported cis-[Pd(2-picoline)4 ]2+ complex. The formation of homoleptic structures, however, was met with considerable steric hindrance at the PdII centers, as observed by the formation of [Pd2 L3 (solvent)2 ]4+ and [Pd2 L2 (solvent)4 ]4+ species when only one type of acridone-based ligand was offered. In contrast, bent phenothiazine ligands with outside-pointing methyl groups showed the ability to form interpenetrated double-cages, as revealed by X-ray crystallography. The general route presented herein enables the assembly of uniform cis-[Pd2 L2 L'2 ]4+ coordination cages, thus furthering the possibility to increase structural and functional complexity in supramolecular systems.