Redox active multi-layered Zn-pPDA MOFs as high-performance supercapacitor electrode material

Harnessing Biomolecule-Infused 2D Multi-layered Luminescent Zn(II) Coordination Polymer for Electrochemical Energy Storage

Selecting the right functional linkers and metal centers is crucial for creating multifunctional crystalline coordination polymers, which show promise in energy storage applications. Herein, a new two-dimensional Zn(II)-based CP, named BPHCC-1, has been synthesized using solvothermal methods with 2-amino terephthalic acid (2ATA) and the biomolecule purine as key building blocks. Purine, which is relatively unexplored in CP synthesis, plays a crucial role in the distinct properties of CPs. BPHCC-1, obtained as a stable crystalline solid, was characterized through various analytical techniques including Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis. The material's stability is attributed to extensive hydrogen bonding, π···π interactions, and coordination of the -NH2 group with the Zn(II) center. BPHCC-1 exhibits bright blue luminescence at 435 nm with a photoluminescence quantum yield of 29% in an aqueous dispersion. Furthermore, it demonstrates significant electrochemical energy storage performance, with a specific capacitance of 84 F g-1 at 3 A g-1 and retaining 64% of its original capacitance after 500 cycles. This study introduces a facile approach to designing multifunctional CPs, showcasing BPHCC-1's potential as a luminescent probe and pseudocapacitive supercapacitor. The findings highlight the versatility of BPHCC-1, suggesting broad opportunities for its use across diverse fields.

Metal-Organic Frameworks and Their Derivatives-Based Nanostructure with Different Dimensionalities for Supercapacitors

With the urgent demand for the achievement of carbon neutrality, novel nanomaterials, and environmentally friendly nanotechnologies are constantly being explored and continue to drive the sustainable development of energy storage and conversion installations. Among various candidate materials, metal-organic frameworks (MOFs) and their derivatives with unique nanostructures have attracted increasing attention and intensive investigation for the construction of next generation electrode materials, benefitting from their unique intrinsic characteristics such as large specific surface area, high porosity, and chemical tunability as well as the interconnected channels. Nevertheless, the poor electrochemical conductivity severely limits their application prospects, hence a variety of nanocomposites with multifarious structures have been designed and proposed from different dimensionalities. In this review, recent advances based on MOFs and their derivatives in different dimensionalities ranging from 1D nanopowders to 2D nanofilms and 3D aerogels, as well as 4D self-supporting electrodes for supercapacitors are summarized and highlighted. Furthermore, the key challenges and perspectives of MOFs and their derivatives-based materials for the practical and sustainable electrochemical energy conversion and storage applications are also briefly discussed, which may be served as a guideline for the design of next-generation electrode materials from different dimensionalities.

Turning precious metal-loaded e-waste to useful catalysts: Investigation into supercilious recovery and catalyst viability for peroxymonosulfate activation

Here, the key tasks to be accomplished are selective precious metal recovery from e-wastewater and their conversion into valuable catalysts for peroxymonosulfate (PMS) activation. In this regard, we developed a hybrid material using 3D functional graphene foam and copper para-phenylenedithol (Cu-pPDT) MOF. The prepared hybrid showed a supercilious recovery of 92-95% even up to five cycles for Au(III) and Pd(II), which can be viewed as a reference for both the 2D graphene and the MOFs family. The outstanding performance has been attributed principally to the impact of diverse functionality as well as the unique morphology of 3D graphene foam, which provided a wide range of surface area and additional active sites in the hybrid frameworks. To prepare the surface-loaded metal nanoparticle catalysts, the sorbed samples recovered after precious metal extraction were calcined at 800 °C. The viability of the developed catalysts for the breakdown of 4-nitrophenol (4-NP) via PMS activation was investigated. Electron paramagnetic resonance spectroscopy (EPR) and experiments with radical scavengers suggest that sulfate and hydroxyl radicals are the main reactive species involved in the breakdown of 4-NP. This is because the active graphitic carbon matrix and the exposed precious metal and copper active sites work together in a way that is more effective.

Advances of Electroactive Metal-Organic Frameworks

The preparation of electroactive metal-organic frameworks (MOFs) for applications of supercapacitors and batteries has received much attention and remarkable progress during the past few years. MOF-based materials including pristine MOFs, hybrid MOFs or MOF composites, and MOF derivatives are well designed by a combination of organic linkers (e.g., carboxylic acids, conjugated aromatic phenols/thiols, conjugated aromatic amines, and N-heterocyclic donors) and metal salts to construct predictable structures with appropriate properties. This review will focus on construction strategies of pristine MOFs and hybrid MOFs as anodes, cathodes, separators, and electrolytes in supercapacitors and batteries. Descriptions and discussions follow categories of electrochemical double-layer capacitors (EDLCs), pseudocapacitors (PSCs), and hybrid supercapacitors (HSCs) for supercapacitors. In contrast, Li-ion batteries (LIBs), Lithium-sulfur batteries (LSBs), Lithium-oxygen batteries (LOBs), Sodium-ion batteries (SIBs), Sodium-sulfur batteries (SSBs), Zinc-ion batteries (ZIBs), Zinc-air batteries (ZABs), Aluminum-sulfur batteries (ASBs), and others (e.g., LiSe, NiZn, H⁺ , alkaline, organic, and redox flow batteries) are categorized for batteries.

Largely Pseudocapacitive Two-Dimensional Conjugated Metal-Organic Framework Anodes with Lowest Unoccupied Molecular Orbital Localized in Nickel-bis(dithiolene) Linkages

Although two-dimensional conjugated metal-organic frameworks (2D c-MOFs) provide an ideal platform for precise tailoring of capacitive electrode materials, high-capacitance 2D c-MOFs for non-aqueous supercapacitors remain to be further explored. Herein, we report a novel phthalocyanine-based nickel-bis(dithiolene) (NiS₄)-linked 2D c-MOF (denoted as Ni₂[CuPcS₈]) with outstanding pseudocapacitive properties in 1 M TEABF₄/acetonitrile. Each NiS₄ linkage is disclosed to reversibly accommodate two electrons, conferring the Ni₂[CuPcS₈] electrode a two-step Faradic reaction with a record-high specific capacitance among the reported 2D c-MOFs in non-aqueous electrolytes (312 F g^-1) and remarkable cycling stability (93.5% after 10,000 cycles). Multiple analyses unveil that the unique electron-storage capability of Ni₂[CuPcS₈] originates from its localized lowest unoccupied molecular orbital (LUMO) over the nickel-bis(dithiolene) linkage, which allows the efficient delocalization of the injected electrons throughout the conjugated linkage units without inducing apparent bonding stress. The Ni₂[CuPcS₈] anode is used to demonstrate an asymmetric supercapacitor device that delivers a high operating voltage of 2.3 V, a maximum energy density of 57.4 Wh kg^-1, and ultralong stability over 5000 cycles.

Conductive Metal-Organic Frameworks for Supercapacitors

As a class of porous materials with crystal lattices, metal-organic frameworks (MOFs), featuring outstanding specific surface area, tunable functionality, and versatile structures, have attracted huge attention in the past two decades. Since the first conductive MOF is successfully synthesized in 2009, considerable progress has been achieved for the development of conductive MOFs, allowing their use in diverse applications for electrochemical energy storage. Among those applications, supercapacitors have received great interest because of their high power density, fast charging ability, and excellent cycling stability. Here, the efforts hitherto devoted to the synthesis and design of conductive MOFs and their auspicious capacitive performance are summarized. Using conductive MOFs as a unique platform medium, the electronic and molecular aspects of the energy storage mechanism in supercapacitors with MOF electrodes are discussed, highlighting the advantages and limitations to inspire new ideas for the development of conductive MOFs for supercapacitors.

Nickel(II) Cluster-Based Pillar-Layered Metal-Organic Frameworks for High-Performance Supercapacitors

Most metal-organic frameworks (MOFs) cannot be used as electrode materials for supercapacitors because of their high costs, poor stabilities in aqueous solutions, inferior intrinsic electrocatalytic activities, and poor conductivities. Herein, the application of two nickel(II) cluster-based pillar-layered MOFs, Ni-mba-Na ([Ni₈(mba)₆(Cl)₂Na(OH^-)₃]_n, H₂mba is 2-mercaptobenzoic acid) and Ni-mba-K ([Ni₈(mba)₆(Cl)₂K(OH^-)₃]_n), as electrode materials are reported. They differ from conductive MOFs because they are insulators with small specific surface areas (<10 m² g^-1), and H²mba is an inexpensive raw material. The conductivities of Ni-mba-Na and Ni-mba-K at 30 °C were 4.002 × 10^-10 and >10^-11 S cm^-1, respectively. They showed excellent supercapacitor performance and stabilities and high inherent densities and specific capacitances. The specific powers of their asymmetric supercapacitors could reach up to 16,000 W kg^-1; the specific energies of Ni-mba-Na and Ni-mba-K were 16.9 and 21.8 Wh kg^-1, respectively. Design recommendations for these MOFs are provided based on their structure and performance differences. This paper shows a novel application of nonconductive MOFs in the energy storage field and design of high-performance electrode materials for supercapacitors.

Electrochemical performance of l-tryptophanium picrate as an efficient electrode material for supercapacitor application

l-Tryptophanium picrate was synthesized and evaluated for its supercapacitor behavior and a 263 F g⁻¹ specific capacitance was achieved.

Excellent supercapacitor and sensor performance of robust cobalt phosphinate ferrocenyl organic framework materials achieved by intrinsic redox and structure properties

A new Co coordination polymer with phosphinates and Fc fragments was synthesized, which can be used as a water sensor and sorbent and also as a supercapacitor electrode.