Selecting and assembling metal ions and bridging ligands can fabricate two-dimensional metal-organic framework nanosheets, which can act as prospective materials for efficient energy applications. ...Thanks to large surface area and more porosity, ultrathin 2D MOFs nanosheets and their derived two-dimensional nanosheet materials exhibit more highly approachable active sites uncovered on the surface, decreased ion diffusion distance and fast electron transfer for energy storage/conversion applications. Herein, this review will summarize the latest developments with discussion of design, fabrication, energy storage as well as conversion performance of 2D MOFs and their-derived two-dimensional materials. Moreover, the development of exfoliated two-dimensional MOFs and their derivatives, as well as the promising trends and prospects in application as excellent-performance electrode materials in batteries, supercapacitors, and electrocatalysis are also present.
Display omitted
•Recent developments of 2D MOF materials for energy applications are reviewed.•Design strategies of 2D MOF related materials are summarized.•Relationship between the structure and performance is discussed in details.•Future research tendency of 2D MOF-related materials is highlighted.
The CNT decorated two-dimensional flaky metal–organic nanosheet composite (Co-MOF-CNT) is designed based on selecting hydroxylated CNT to modify the synthesis process of Co-MOF. The flaky dispersed ...sheet structure possesses more exposed surfaces and porous structures for Co-MOF-CNT composite, which can provide more active reaction sites and promote the rapid transmission of Li/K-ions.
Display omitted
•The CNT boosted 2D Co-MOF nanosheets are designed and fabricated.•The Co-MOF-CNT nanosheets deliver high specific surface area with more exposed pore structure.•The Co-MOF-CNT electrode achieves enhanced electrochemical performance as anodes for LIBs and PIBs.•Lithium-reaction activation on Co2+ centers, CC and CO groups can be boosted for Co-MOF-CNT.
Flaky nanosheets with superior molecular structures and functions are indispensable for high-performance lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs). Herein, through a simple dispersion method, two-dimensional Co-MOF-CNT nanosheets are prepared by adding nanotubes (CNT) during the synthesis of MOF under microwave-assisted radiation conditions. The flaky dispersed sheet structure possesses more exposed surfaces and porous structures for Co-MOF-CNT, which is beneficial to offering numerous active sites and promoting the rapid transmission of Li/K-ions. Therefore, when applied as negative electrode for LIB and PIB, the Co-MOF-CNT nanosheets can provide an extremely enhanced reversible capacity (1451/286 mAh g−1 for LIBs/PIBs after 100 cycles at 100 mA g−1). In view of ex-situ XPS result, in-situ FTIR result and electrochemical detection, the excellent electrochemical performance is determined due to the activated lithium-reaction involving metal centers, CO groups and CC groups from benzene rings. The research on lithium/potassium reaction functional groups of MOF nanosheets with more activated energy-storage sites would further provide guidance for the exploration on superior-performance electrodes for future alkali metal secondary batteries.
Bimetal-organic-framework is used to fabricate carbon-coated Co/Zn bimetal selenide microrod for the first time, which exhibits good lithium-storage properties.
Display omitted
•The carbon-coated ...Co-Zn mixed-metal selenide microrod is investigated as the Li-battery electrode for the first time.•Bimetal-organic framework is used as the precursor.•The carbon-coated Co-Zn mixed-metal selenide microrod shows large Li-storage capacity and very long cycle life.
Transitional metal selenides can be explored as a class of candidate electrodes for lithium-ion batteries, because of their large lithium storage ability, wide availability, and good safety. Besides, hybridization with carbonaceous materials, as well as the design of porous or hollow structure, would be effective approaches to improve the cycling stability and rate performance of transitional metal selenide electrodes. By a facile bimetal-organic-framework approach, a carbon-coated bimetal selenide microrod composite (Co-Zn-Se@C) is fabricated for the first time in this work. On account of the MOF-derived porous particle-assembled structure, along with the buffering effect between two metal components, the Co-Zn-Se@C electrode manifests extremely large reversible capacity of 949 mAh g−1 after 500 cycles with good high-rate capability for lithium ion batteries. It would extend the synthesis and application of metal selenides in the field of energy storage.
A small amount of tin ions modified covalent organic framework hollow microsphere (Sn@COF-hollow) is designed and demonstrated with more active sites, facilitated lithium-storage kinetic and highly ...reversible large capacities.
Display omitted
•Sn-doped COF layer-assembled hollow microspherical composite is fabricated via the Sn-N coordination.•The Sn@COF-hollow is adopted as the electrode for lithium-ion battery for the first time.•Enhanced electrochemical performances can be achieved for the Sn@COF-hollow electrode.•Lithium-reaction activation on Sn centers, CC and CN groups can be boosted for the Sn@COF-hollow electrode.
Covalent-organic frameworks (COFs) and related composites show an enormous potential in next-generation high energy-density lithium-ion batteries. However, the strategy to design functional covalent organic framework materials with nanoscale structure and controllable morphology faces serious challenges. In this work, a layer-assembled hollow microspherical structure (Sn@COF-hollow) based on the tin-nitrogen (Sn-N) coordination interaction is designed. Such carefully-crafted hollow structure with large exposed surface area and metal center decoration endows the Sn@COF-hollow electrode with more activated lithium-reaction sites, including Sn ions, carbon-nitrogen double bond (CN) groups and carbon-carbon double bond (CC) units from aromatic benzene rings. Besides, the layer-assembled hollow structure of the Sn@COF-hollow electrode can also alleviate the volume expansion of electrode during repeated cycling, and achieve fast electrons/ions transmission and capacitance-dominated lithium-reaction kinetics, further leading to enhanced cycling performance and rate properties. In addition, the effective combination of the inorganic metal and organic framework components in the Sn@COF-hollow electrode can promote its improved conductivity and further enhance lithium-storage properties. Benefited from these merits, the Sn@COF-hollow electrode delivers highly reversible large capacities of 1080 mAh g−1 after 100 cycles at 100 mA g−1 and 685 mAh g−1 after 300 cycles at 1000 mA g−1. This work provides an interesting and effective way to design COF-based anodes of lithium-ion battery with improved electrochemical performances.
Exploration of the structures and architectural design of crystalline porous metal–organic coordination polymer (MOCP) materials with boosted active lithium-storage functional groups is still an ...urgent requirement for MOCP structures with improved lithium-storage properties when applied as the electrodes for next-generation lithium-ion batteries. Herein, we synthesize a carbonyl functional group modified Co-based metal–organic coordination polymer (Co-BDBA-MOCP) via a one-step facile microwave-assisted solvothermal method and apply it as the electrode material for a lithium-ion battery for the first time. The unique petals-assembled rose-shaped morphology endows the Co-BDBA-MOCP structure with a more exposed surface and porous structure, which can provide more active sites and facilitate fast Li-ion transport. Thus, the boosted lithium-reaction activation of the Co2+ centers, the CC groups of the benzene rings, and the modified CO groups in the structure and further the extremely enhanced electrochemical performance can be achieved for the Co-BDBA-MOCP electrode. This electrode delivers an initial reversible capacity of 1401 mAh g–1 at a current density of 100 mA g–1 with ∼1150 mAh g–1 retained after 100 cycles, and a large reversible capacity of 743 mAh g–1 after 350 cycles at a large current of 500 mA g–1. The exploration of the active lithium reaction units modified metal–organic frameworks with more activated functional groups for lithium storage would further shed light on high-performance electrodes for next-generation rechargeable batteries.
Covalent organic framework, as an emerging porous nano‐frame structure with pre‐designed structure and custom properties, has been demonstrated as a prospective electrode for rechargeable Li‐ion ...batteries. For improving the reversible capacity and long‐term cycle stability of COF materials, we propose a GQDs modified COF material (COF‐GQDs) and apply it as the anode for LIBs for the first time. This COF‐GQDs electrode delivers enhanced long‐term cycling performance with a large capacity of ∼820 mAh g−1 after 300 cycles at 100 mA g−1 and an improved rate performance. The enhanced lithium‐storage performance, in terms of obvious‐shortened activation process and high reversible capacities, can be attributed to the modification of carboxyl GQDs, which would activate more active sites (activated C=C groups from benzene rings) for lithium‐storage, and provide fast lithium‐ion transportation kinetic. Besides, the decreased interphase resistance, enhanced electronic conductivity, and prevented aggregation of needle‐flake COF structure, originated from the addition of GQDs, which lead to the enhanced improved cycling stability of the COF‐GQDs electrode. This manuscript can promote the further exploration on the design of COF‐related materials with modification of functionalized carbonaceous materials to achieve enhanced lithium‐storage properties for next‐generation energy storage.
Functionalized graphene quantum dots (GQDs) modified dioxin‐linked covalent organic frameworks (COF) are fabricated and applied as anode material of lithium‐ion battery for the first time. The modification of carboxyl GQDs leads to more active sites, fast lithium‐ion transportation kinetics, and enhanced electronic conductivity, resulting in enhanced lithium‐storage properties for the graphene quantum dots modified covalent organic frameworks (COF‐GQDs) electrode
Due to the adjustable structure and the broad application prospects in energy and other fields, the exploration of porous organic materials metal‐organic polymers (MOPs), covalent organic frameworks ...(COFs), etc. has attracted extensive attention. In this work, an imine‐induced metal‐organic and covalent organic coexisting framework (Co−MOP@COF) hybrid was designed based on the combination between the amino units from the organic ligands of Co−MOP and the aldehyde groups from COF. The obtained Co−MOP@COF hybrid with layer‐decorated microsphere morphology exhibited good electrochemical cycling performance (a large reversible capacity of 1020 mAh g−1 after 150 cycles at 100 mA g−1 and a reversible capacity of 396 mAh g−1 at 500 mA g−1) as the anode for Li‐ion batteries. The coexisting framework structure endowed the Co–MOP@COF hybrid with more surface area exposed in the exfoliated COF structure, which provided rapid Li‐ion diffusion, better electrolyte infiltration, and effective activation of functional groups. Therefore, the Co−MOP@COF hybrid material achieved an enhanced Li storage mechanism involving multi‐electron redox reactions, related to the CoII center and organic groups (C=C groups of benzene rings and C=N groups), and furthermore improved electrochemical performance.
Two in one: A metal‐organic and covalent organic coexisting framework structure is designed based on the imine‐induced combination between the imine‐based C=N coupled covalent organic framework (COF) and Co‐centered metal‐organic polymer (MOP). The coexisting framework structure retains the exfoliated COF structure with large exposed surface area, along with the resultant multi‐electron redox reaction involving metal centers and organic functional groups in the Co−MOP@COF hybrid electrode for Li‐ion batteries.
With the development and popularity of portable electronic devices, there is an urgent need for flexible energy storage devices suitable for mass production. We report freestanding paper electrodes ...for supercapacitors fabricated via a simple but efficient two-step method. Nitrogen-doped graphene (N-rGO) was first prepared via a hydrothermal method. This not only obtained nitrogen atom-doped nanoparticles but also formed reduced graphene oxide. Pyrrole (Py) was then deposited on the bacterial cellulose (BC) fibers as a polypyrrole (PPy) pseudo-capacitance conductive layer by in situ polymerization and filtered with nitrogen-doped graphene to prepare a self-standing flexible paper electrode with a controllable thickness. The synthesized BC/PPy/N15-rGO paper electrode has a remarkable mass specific capacitance of 441.9 F g−1, a long cycle life (96 % retention after 3000 cycles), and excellent rate performance. The BC/PPy/N15-rGO-based symmetric supercapacitor shows a high volumetric specific capacitance of 244 F cm−3 and a max energy density of 67.9 mWh cm−3 with a power density of 1.48 W cm−3, suggesting that they will be promising materials for flexible supercapacitors.
Display omitted
Abstract
Base editing technology is an ideal solution for treating pathogenic single-nucleotide variations (SNVs). No gene editing therapy has yet been approved for eye diseases, such as retinitis ...pigmentosa (RP). Here, we show, in the
rd10
mouse model, which carries an SNV identified as an RP-causing mutation in human patients, that subretinal delivery of an optimized dual adeno-associated virus system containing the adenine base editor corrects the pathogenic SNV in the neuroretina with up to 49% efficiency. Light microscopy showed that a thick and robust outer nuclear layer (photoreceptors) was preserved in the treated area compared with the thin, degenerated outer nuclear layer without treatment. Substantial electroretinogram signals were detected in treated
rd10
eyes, whereas control treated eyes showed minimal signals. The water maze experiment showed that the treatment substantially improved vision-guided behavior. Together, we construct and validate a translational therapeutic solution for the treatment of RP in humans. Our findings might accelerate the development of base-editing based gene therapies.
