Auswahl der wissenschaftlichen Literatur zum Thema „Conductive 2D-MOFs“

Two-dimensional conductive metal–organic frameworks (2D c-MOFs) have attracted research attention, benefitting from their unique properties such as superior electronic conductivity, designable topologies, and well-defined catalytic/redox-active sites. These advantages enable 2D c-MOFs as promising candidates in electrochemical energy applications, including supercapacitors, batteries and electrocatalysts. This mini-review mainly highlights recent advancements of 2D c-MOFs in the utilization for electrochemical energy storage, as well as the forward-looking perspective on the future prospects of 2D c-MOFs in the field of electrochemical energy.Table of content:1 Introduction2 Design Principles of 2D c-MOFs3 Synthesis of 2D c-MOFs4 2D c-MOFs for Electrochemical Energy Storage4.1 Supercapacitors4.2 Metallic Batteries4.2.1 Lithium-Ion Batteries4.2.2 Sodium-Ion Batteries4.2.3 Zinc-Ion Batteries4.2.4 Sodium–Iodine Batteries4.2.5 Lithium–Sulfur Batteries4.2.6 Potassium-Ion Batteries5 2D c-MOFs for Electrochemical Energy Conversion6 Conclusions and Outlook

Recent progress on 2D conductive MOFs and 2D layered MOFs containing pillar-layered MOFs and 2D nanosheets as electrode materials in SCs is reviewed, including synthetic design strategies, electrochemical performances, and working mechanisms.

Recent progress in MOF materials for SCs with different spatial dimensions, such as 2D MOFs, including conductive MOFs and nanosheets, and 3D MOFs, categorized as single metallic and multiple metallic MOFs, are reviewed.

For the first time, we report herein bottom-up fabrication of a conductive nickel phthalocyanine-based 2D MOF and use it as a highly active electrocatalyst for OER (overpotential < 250 mV) without further pyrolysis or adding conductive materials, which can facilitate the development of 2D MOFs for energy applications.

Two-dimensional (2D) conductive metal–organic frameworks (MOFs) have emerged as a unique class of multifunctional materials with broad applicability in electronics, chemical sensing, gas capture, catalysis, and energy conversion and storage.

Recently, two-dimensional conductive MOFs (2D c-MOFs) with improved intrinsic electrical conductivity have been synthesized and employed as electrocatalysts, gas sensors, supercapacitors, and so on. In previous literature, 2D c-MOFs were usually synthesized initially as the powder/film through solvothermal approach, after which a transfer and/or reshaping process is necessary for the electrode fabrication [1-3]. In most cases, the electrodes of 2D c-MOFs were prepared with conductive additives and binders through the slurry coating method [2]. In doing so, their superior intrinsic conductivity over traditional MOFs was obscured. Moreover, the use of additives might reduce the effective surface area and negatively affect long-term cycling performance. To avoid the use of additives, 2D c-MOFs could be pressed into self-supported pellets. Unfortunately, due to dense packing under high pressure, many MOF particles inside pellets are not able to capture ions, leading to the decrease in capacitance. Until now, restrained by flawed electrode fabrication approaches, the potential of 2D c-MOFs in supercapacitors was still far from fully exploited. The electrochemical deposition technique is a promising approach to fabricating 2D c-MOFs as electrodes, with significant advantages over above methods [3]. On the one hand, electrochemical deposition allows in situ growth of 2D c-MOFs on substrates, thus reducing the cost and simplifying the process. On the other hand, binders, conductive additives, and compacting processes are no longer necessary, which will help improve the capacitor performance [4]. Moreover, the electrochemical deposition process could be conducted at mild conditions and all parameters could be precisely controlled, which makes it a mild, facile method with good reproducibility. To date, there is still no study to prepare 2D c-MOFs through direct electrochemical deposition. In 2018, we reported the first synthesis of phthalocyanine-based 2D c-MOF nanosheets (NiPc-MOF) and its outstanding performance toward water oxidation [3]. Owing to the high electrical conductivity (~0.2 S cm-1) and large surface area (~593 m2 g-1), NiPc-MOF is also considered as a promising electrode material for supercapacitors. In this work, NiPc-MOF was grown in situ on nickel foam (NF) via the anodic electrodeposition (AED) approach (abbreviated as NiPc-MOFAED or NiPc-MOFAED@NF, Fig. 1a-d). As far as we know, the AED approach has never been used for the synthesis of 2D c-MOFs. Remarkably, the as-prepared NiPc-MOFAED@NF can be directly utilized as electrodes for flexible supercapacitors, which has also been well explored in this work. The simplified electrode fabrication process, that does not involve binders and conductive additives, would significantly reduce the cost and will have enormous potential for the applications of NiPc-MOF in energy storage. The outstanding performance of the NiPc-MOFAED@NF supercapacitor (Fig. 1e-f), including high specific areal capacitances (11.5 mF cm-2 in aqueous electrolyte and 22.1 mF cm-2 in organic electrolyte), preeminent areal power density (1.35 mW cm-2 at 1 mA cm-2, organic system) and energy density (22.4 μWh cm-1 at 0.1 mA cm-2, organic system), robust cycling stability as well as prominent mechanical flexibility, were further disclosed by electrochemical measurements. This present work not only reported an advanced phthalocyanine-based MOF material for a high-performance supercapacitor, but also opens up a novel avenue for the in situ growth of the 2D c-MOF. [Figure insert] Figure 1. (a) Schematic illustration of NiPc-NiN4-MOF; (b) XRD pattern, (c) High-resolution TEM image, and (d) EDX mappings of NiPc-NiN4-MOF. NiPc-MOFAED@NF-based supercapacitor in aqueous system (PVA/LiClO4). (a) GCD curves at various current densities of 0.04-0.4 mA cm−2. (b) CV curves of supercapacitor at bending angles of 0°, 30°, 60°, and 90°. Scan rate: 20 mV s−1. (c) Photograph of a red LED powered by the three series-connected supercapacitors; NiPc-MOFAED@NF-based supercapacitor in organic system (TEABF4/Acetonitrile). (d) GCD curves at various current densities of 0.1-1 mA cm−2. (e) CV curves of supercapacitor at bending angles of 0°, 30°, 60°, and 90°. Scan rate: 100 mV s−1. (f) Photograph of a green LED powered by one supercapacitor. (Ref: Journal of Power Sources, 2022, 526: 231163) Copyright 2022 Elsevier. Reference: [1] Jia, Hongxing, et al. "In situ anodic electrodeposition of two-dimensional conductive metal-organic framework@nickel foam for high-performance flexible supercapacitor." Journal of Power Sources 526 (2022): 231163. [2] Lu, Shun, et al. "Two-dimensional conductive phthalocyanine-based metal–organic frameworks for electrochemical nitrite sensing." RSC Advances 11.8 (2021): 4472-4477. [3] Jia, Hongxing, et al. "A novel two-dimensional nickel phthalocyanine-based metal–organic framework for highly efficient water oxidation catalysis." Journal of Materials Chemistry A 6.3 (2018): 1188-1195. [4] Yan, Caihong, et al. "Hydrothermal synthesis of vanadium doped nickel sulfide nanoflower for high-performance supercapacitor." Journal of Alloys and Compounds 928 (2022): 167189. Figure 1

Conductive metal-organic frameworks (MOFs) are porous yet electric conductive, promising for many applications such as electronics, electrocatalysts, and energy storage. However, traditional solvothermal and microwave synthesis methods usually lead to MOF powders that cannot be used directly, i.e., additional processes like adding binders, casting, and thermal treatments are required for their applications. Therefore, shaping conductive MOFs into 2D thin films is attracting attention from researchers. Here we report a cathodic deposition for the one-step fabrication of conductive MOF films, which features a fast and convenient deposition process. In this method, the deposition precursor contains metal salts and organic linkers (no supporting electrolyte is needed). When an external negative bias is applied on the conductive working electrode (WE), the linkers can be deprotonated on its surface. A conductive MOF film can thus be deposited on the WE by coordinating the deprotonated linkers and metal nodes. As demonstrating examples, Cu/Ni-HHTP (HHTP: 2,3,6,7,10,11-hexahydroxytriphenylene) and Cu-BTPA (BTPA: benzene-1,3,5-triyltriboronic acid) are cathodically deposited on indium-doped tin oxide (ITO) glass substrates. The measured conductivity of these deposited conductive MOF films varies from 0.01 to 0.1 S cm-1 depending on their thickness and composition. Both of the fabricated conductive MOF films show good performance on supercapacitors and electrochemical sensing.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two innovative classes of porous coordination polymers. MOFs are three-dimensional materials made up of secondary building blocks comprised of metal ions/clusters and organic ligands whereas COFs are 2D or 3D highly porous organic solids made up by light elements (i.e., H, B, C, N, O). Both MOFs and COFs, being highly conjugated scaffolds, are very promising as photoactive materials for applications in photocatalysis and artificial photosynthesis because of their tunable electronic properties, high surface area, remarkable light and thermal stability, easy and relative low-cost synthesis, and structural versatility. These properties make them perfectly suitable for photovoltaic application: throughout this review, we summarize recent advances in the employment of both MOFs and COFs in emerging photovoltaics, namely dye-sensitized solar cells (DSSCs) organic photovoltaic (OPV) and perovskite solar cells (PSCs). MOFs are successfully implemented in DSSCs as photoanodic material or solid-state sensitizers and in PSCs mainly as hole or electron transporting materials. An innovative paradigm, in which the porous conductive polymer acts as standing-alone sensitized photoanode, is exploited too. Conversely, COFs are mostly implemented as photoactive material or as hole transporting material in PSCs.

Les composés metal organic framework conducteurs c-MOF font partie d’une nouvelle classe de matériaux 2D, composés d'ions métalliques liés à des ligands organiques dans un réseau cristallin. Au cours de cette thèse nous avons étudié la croissance de 2D-MOF bien ordonnés M3C6O6, sous ultra-haut-vide, par réaction de surface entre des atomes de métaux de transition de cuivre et de manganèse et la molécule tétrahydroxyquinone THQ sur la surface d’argent Ag (111). Ces matériaux 2D sont étudiés par microscopie à effet tunnel (STM), diffraction d'électrons lents à basse énergie (LEED) et spectroscopie de photoélectron X (XPS) en fonction des conditions de croissances (température du substrat, flux). Cette étude permet de combiner une caractérisation à l’échelle atomique et une caractérisation chimique pour la compréhension fondamentale des mécanismes de croissance après réaction entre des atomes métalliques et des composés organiques. Ces propriétés électroniques et magnétiques ont été étudiées conjointement par la théorie de la fonctionnelle de la densité (DFT). En particulier pour étudier le rôle du substrat métallique sur les propriétés électroniques des 2D-MOF. Un récapitulatif de cette étude théorique est présenté afin de conclure sur les perspectives offertes par cette étude
Conductive metal organic framework (c-MOF) compounds are a new class of 2D materials, composed of metal ions bound to organic ligands in a crystal lattice. In this thesis, we studied the growth of c-MOF M3C6O6, by surface reaction between transition metal atoms of copper and manganese and the tetrahydroxyquinone molecule THQ on the surface of silver Ag (111) under ultra-high vacuum. The study of these 2D materials is performed by Scanning Tunneling Microscopy (STM), Low Energy-Electron Diffraction (LEED) and X-ray Photoelectron Spectroscopy (XPS) as a function of growth conditions (substrate temperature, flux). The aim of this study is to combine atomic and chemical characterizations for the fundamental understanding of the growth mechanisms after reaction between metal atoms and organic compounds. These electronic and magnetic properties have been studied conjointly by Density Functional Theory (DFT). In particular to study the role of the metal substrate on the electronic properties of the 2D-MOF. A summary of this theoretical study is presented in order to conclude on other perspectives

We have incorporated perfectly matched layers (PMLs) into our iterative Fourier modal method to tackle radiation losses in microstructured optical fibers (MOFs). For the inclusion of PMLs, first we have adapted our numerical procedure both to handle conductive and absorptive anisotropic materials and to search directly for the eigenvalues that are close to a certain fixed value. Secondly, we have designed a novel type of cylindrical PMLs in which the conductivity increases radially, suiting quite well with the fiber radiation modes. The description of the PMLs as an anisotropic material has allowed us to use a different coordinate system to describe either the 2D wave equation or the PMLs themselves. Once the calibration process of the PMLs is successfully ended, radiation losses can be estimated accurately. Finally, this technique is applied to model radiation losses for specialty MOFs used for sensing applications.