Enhanced Capacitive Deionization of Hollow Mesoporous Carbon Spheres/MOFs Derived Nanocomposites by Interface-Coating and Space-Encapsulating Design.

Exploring new carbon-based electrode materials is quite necessary for enhancing capacitive deionization (CDI). Here, hollow mesoporous carbon spheres (HMCSs)/metal-organic frameworks (MOFs) derived carbon materials (NC(M)/HMCSs and NC(M)@HMCSs) are successfully prepared by interface-coating and space-encapsulating design, respectively. The obtained NC(M)/HMCSs and NC(M)@HMCSs possess a hierarchical hollow nanoarchitecture with abundant nitrogen doping, high specific surface area, and abundant meso-/microporous pores. These merits are conducive to rapid ion diffusion and charge transfer during the adsorption process. Compared to NC(M)/HMCSs, NC(M)@HMCSs exhibit superior electrochemical performance due to their better utilization of the internal space of hollow carbon, forming an interconnected 3D framework. In addition, the introduction of Ni ions is more conducive to the synergistic effect between ZIF(M)-derived carbon and N-doped carbon shell compared with other ions (Mn, Co, Cu ions). The resultant Ni-1-800-based CDI device exhibits excellent salt adsorption capacity (SAC, 37.82 mg g-1) and good recyclability. This will provide a new direction for the MOF nanoparticle-driven assembly strategy and the application of hierarchical hollow carbon nanoarchitecture to CDI.

Confining Iodine into Metal-Organic Framework Derived Metal-Nitrogen-Carbon for Long-Life Aqueous Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries (AZIBs) are highly appealing for energy requirements owing to their safety, cost-effectiveness, and scalability. However, the inadequate redox kinetics and severe shuttling effect of polyiodide ions impede their commercial viability. Herein, several Zn-MOF-derived porous carbon materials are designed, and the further preparation of iron-doped porous carbon (Fe-N-C, M9) with varied Fe doping contents is optimized based on a facile self-assembly/carbonization approach. M9, with atomic Fe coordinated to nitrogen atoms, is employed as an efficient cathode host for AZIBs. Functional modifications of porous carbon hosts involving the doping species and levels are investigated. The adsorption tests, in situ Raman spectroscopy, and in situ UV-vis results demonstrate the adsorption capability and charge-discharge mechanism for the iodine species. Furthermore, experimental findings and theoretical analyses have proven that the redox conversion of iodine is enhanced through a physicochemical confinement effect. This study offers basic principles for the strategic design of single-atom dispersed carbon as an iodine host for high-performance AZIBs. Flexible soft-pack battery and wearable microbattery applications also have implications for future long-life aqueous battery designs.

Thiosalicylic-Acid-Mediated Coordination Structure of Nickel Center via Thermodynamic Modulation for Aqueous Ni-Zn Batteries.

Uniquely functional nanocomplexes with rich coordination environments are critical in energy storage. However, the construction of structurally versatile nanocomplexes remains challenging. In this study, a nickel-based complex with structural variations is designed via thermodynamic modulation using a dual-ligand synthesis strategy. A nickel-based nanomaterial (NiSA-SSA-160) with a large specific surface area is synthesized around the competing coordination of the host and guest molecules that differ in terms of the chemical properties of the O and S elements. Concurrently, the coordination environment of NiSA-SSA-160 is investigated via X-ray absorption fine structure spectroscopy. The thiol functional groups synergistically induced an electron-rich Ni structure, thus increasing the electron density of the central atom. The electrochemical performance of an assembled NiSA-SSA-160//Zn@CC battery is shown to improve significantly, with a maximum energy density of 0.54 mWh cm-2 and a peak power density of 49.49 mW cm-2. This study provides a new perspective regarding coordination transformations and offers an idea for the design of functionally rich nanomaterials.

Recent progress of MOF-functionalized nanocomposites: From structure to properties.

Metal-organic frameworks (MOFs) are novel crystalline porous materials assembled from metal ions and organic ligands. The adaptability of their design and the fine-tuning of the pore structures make them stand out in porous materials. Furthermore, by integrating MOF guest functional materials with other hosts, the novel composites have synergistic benefits in numerous fields such as batteries, supercapacitors, catalysis, gas storage and separation, sensors, and drug delivery. This article starts by examining the structural relationship between the host and guest materials, providing a comprehensive overview of the research advancements in various types of MOF-functionalized composites reported to date. The review focuses specifically on four types of spatial structures, including MOFs being (1) embedded in nanopores, (2) immobilized on surface, (3) coated as shells and (4) assembled into hybrids. In addition, specific design ideas for these four MOF-based composites are presented. Some of them involve in situ synthesis method, solvothermal method, etc. The specific properties and applications of these materials are also mentioned. Finally, a brief summary of the advantages of these four types of MOF composites is given. Hopefully, this article will help researchers in the design of MOF composite structures.

Co3 O4 Quantum Dots Intercalation Liquid-Crystal Ordered-Layered-Structure Optimizing the Performance of 3D-Printing Micro-Supercapacitors.

The effects of near surface or surface mechanisms on electrochemical performance (lower specific capacitance density) hinders the development of 3D printed micro supercapacitors (MSCs). The reasonable internal structural characteristics of printed electrodes and the appropriate intercalation material can effectively compensate for the effects of surface or near-surface mechanisms. In this study, a layered structure is constructed inside an electrode using an ink with liquid-crystal characteristics, and the pore structure and oxidation active sites of the layered electrode are optimized by controlling the amount of Co3 O4 -quantum dots (Co3 O4 QDs). The Co3 O4 QDs are distributed in the pores of the electrode surface, and the insertion of Co3 O4 QDs can effectively compensate for the limitations of surface or near-surface mechanisms, thus effectively improving the pseudocapacitive characteristics of the 3D-printed MSCs. The 3D printed MSC exhibits a high area capacitance (306.13 mF cm-2 ) and energy density (34.44 µWh cm-2 at a power density of 0.108 mW cm-2 ). Therefore, selecting the appropriate materials to construct printable electrode structures and effectively adjusting material ratios for efficient 3D printing are expected to provide feasible solutions for the construction of various high-energy storage systems such as MSCs.

Mesoporous Iron Family Element (Fe, Co, Ni) Molybdenum Disulfide/Carbon Nanohybrids for High-Performance Supercapacitors.

As the demand for fuel continues to increase, the development of energy devices with excellent performance is crucial. Supercapacitors (SCs) are attracting attention for their advantages of high specific energy and a long cycle life. At present, the development of high-performance electrode materials is the main point for research and development of SCs. Transition metal sulfides have the advantages of a large interlayer space and high theoretical capacity, making them promising electrode materials. Herein, we reported a series of ultrathin mesoporous iron family element (Fe, Co, Ni) molybdenum disulfide (MxMo1-xS2/C, M = Fe, Co, and Ni) by a template method. The original monolayer mesoporous structure of MoS2/C was maintained, and accumulation and agglomeration of MoS2/C were avoided. Based on our investigations, the best performance was that of CoxMo1-xS2/C nanohybrids. Furthermore, the concentrations of Co and Mo ions were modulated to obtain the best performance, in which Mo and Co ions were released at 1:1, 1:2, and 1:3 ratios and they were named CoxMo1-xS2/C-1, CoxMo1-xS2/C-2, and CoxMo1-xS2/C-3, respectively. Overall, these materials represent a significant improvement and show promise as high-performance SC electrode materials due to their enhanced capacitance and stability. At a current density of 0.5 A g-1, CoxMo1-xS2/C-2 has the optimal specific capacitance of 184 F g-1. CoxMo1-xS2/C-2 as an SC electrode exhibited better reversible capacity and cycling stability than MoS2/C, which is an improvement over MoS2/C regarding reversible capacity and cycling stability.

Space-Confined Metal Ion Strategy for Carbon Materials Derived from Cobalt Benzimidazole Frameworks with High Desalination Performance in Simulated Seawater.

Various metal ions with different valence states (Mg2+ , Al3+ , Ca2+ , Ti4+ , Mn2+ , Fe3+ , Ni2+ , Zn2+ , Pb2+ , Ba2+ , Ce4+ ) are successfully confined in quasi-microcube shaped cobalt benzimidazole frameworks using a space-confined synthesis strategy. More importantly, a series of derived carbon materials that confine metal ions are obtained by high-temperature pyrolysis. Interestingly, the derived carbon materials exhibited electric double-layer and pseudocapacitance properties because of the presence of metal ions with various valence states. Moreover, the presence of additional metal ions within carbon materials may create new phases, which can accelerate Na+ insertion/extraction and thus increase electrochemical adsorption. Density functional theory results showed that carbon materials in which Ti ions are confined exhibit enhanced insertion/extraction of Na+ resulting from the presence of the characteristic anatase crystalline phases of TiO2 . The Ti-containing materials have an impressive desalination capacity (62.8 mg g-1 ) in capacitive deionization (CDI) applications with high cycling stability. This work provides a facile synthetic strategy for the confinement of metal ions in metal-organic frameworks and thus supports the further development of derived carbon materials for seawater desalination by CDI.

Design of Uniform Hollow Carbon Nanoarchitectures: Different Capacitive Deionization between the Hollow Shell Thickness and Cavity Size.

Carbon-based materials with high capacitance ability and fast electrosorption rate are ideal electrode materials in capacitive deionization (CDI). However, traditional carbon materials have structural limitations in electrochemical and desalination performance due to the low capacitance and poor transmission channel of the prepared electrodes. Therefore, reasonable design of electrode material structure is of great importance for achieving excellent CDI properties. Here, uniform hollow carbon materials with different morphologies (hollow carbon nanospheres, hollow carbon nanorods, hollow carbon nano-pseudoboxes, hollow carbon nano-ellipsoids, hollow carbon nano-capsules, and hollow carbon nano-peanuts) are reasonably designed through multi-step template method and calcination of polymer precursors. Hollow carbon nanospheres and hollow carbon nano-pseudoboxes exhibit better capacitance and higher salt adsorption capacity (SAC) due to their stable carbonaceous structure during calcination. Moreover, the effects of the thickness of the shell and the size of the cavity on the CDI performance are also studied. HCNSs-0.8 with thicker shell (≈20 nm) and larger cavity (≈320 nm) shows the best SAC value of 23.01 mg g-1 due to its large specific surface area (1083.20 m2  g-1 ) and rich pore size distribution. These uniform hollow carbon nanoarchitectures with functional properties have potential applications in electrochemistry related fields.

HCl-activated porous nitrogen-doped carbon nanopolyhedras with abundant hierarchical pores for ultrafast desalination.

Exploring an emerging carbon-based material with optimized structure and controlled porosity is of significance for further heightening the capacitive deionization (CDI) performance and solving the problem of emergency fresh water supply. Herein, a porous nitrogen-doped carbon nanopolyhedra with hierarchical pores prepared via using zeolite-type metal-organic framework (ZIF-8) as precursor is reported and used for CDI. In order to prepare the nanomaterials with abundant hierarchical pore structure, the synthetic route of carbonization followed by HCl-activation is adopted. The resulting nitrogen-doped carbon materials exhibit a bimodal porosity containing micro- and meso-pores, high specific surface area, and numerous exposed adsorption active sites. The excellent performance in structure ensures the ultrahigh desalination capacity of 37.52 mg g-1 and excellent recyclability (retained 90% over 30 cycles) of the as-prepared carbon electrode material. Notably, the above electrode demonstrates ultrafast desalination rate of 16.01 mg g-1 min-1, which is 2-8 times faster than the conventional carbon materials. This present work may provide a new insight for developing efficient MOF-derived CDI electrode materials and realizing rapid water resource supply in emergencies such as outdoor survival or unexpected natural disasters.

Hollow mesoporous carbon nanospheres space-confining ultrathin nanosheets superstructures for efficient capacitive deionization.

In this work, we propose a novel strategy to fabricate nickel silicate nanoflakes inside hollow mesoporous carbon spheres (Ni3Si2O5(OH)4/C). Hollow mesoporous carbon spheres (HMCSs) can well regulate and limit the growth of Ni3Si2O5(OH)4 nanosheets, which obviously enhance the structural stability and conductivity of the composites. The core-shell Ni3Si2O5(OH)4/C superstructure has been proven to possess an extremely excellent electrosorption capacity of 28.7 mg g-1 at 1.2 V under a NaCl concentration of 584 mg L-1 for capacitive deionization (CDI). This outstanding property can be attributed to the core-shell superstructure with ultrathin Ni3Si2O5(OH)4 nanosheets as the stable core and mesoporous carbon as the conductive shell. This work will provide a direction for the application of core-shell superstructure carbon-based nanomaterials as high-performance electrode materials for CDI.

Regulation of the Ni2+ Content in a Hierarchical Urchin-Like MOF for High-Performance Electrocatalytic Oxygen Evolution.

The exploitation of efficient non-precious electrocatalysts for the oxygen evolution reaction is extremely important but remains tremendously challenging. Here, we prepared a series of hierarchical urchin-like bimetallic Ni/Zn metal-organic framework nanomaterials that served as high-performance electrocatalysts, by regulating the Ni2+/Zn2+ ratio and using a facile one-step hydrothermal method for the application of the oxygen evolution reaction. The structure of the hierarchical urchin-like microspheres could improve the utilization efficiency of the active species by facilitating the diffusion of gas and reducing the transport resistance of ions, due to its features of a large interfacial area and convenient diffusion channels. In addition, we found that the higher the Ni ratio was, the better the electrocatalytic performance of these bimetallic metal-organic framework nanomaterials.

Ultrathin nanosheet-assembled [Ni3(OH)2(PTA)2(H2O)4]·2H2O hierarchical flowers for high-performance electrocatalysis of glucose oxidation reactions.

Ultrathin two-dimensional (2D) metal-organic framework (MOF) nanosheets have been regarded as very promising electrocatalysts, although more efforts need to be devoted to improve their electrocatalytic activity. Here, we have developed ultrathin 2D nanosheet-assembled [Ni3(OH)2(PTA)2(H2O)4]·2H2O (Ni-MOF, PTA = p-benzenedicarboxylic acid) hierarchical flowers, which demonstrate superior electrocatalytic activity and excellent stability for the glucose oxidation reaction (GOR). The ultrathin 2D nanosheet-assembled flower-like nanostructure can provide interconnected open pores, accounting for its high electrocatalytic performance. Additionally, most of the ultrathin 2D nanosheets are in close contact with each other, making the ultrathin 2D nanosheets more stable. Furthermore, the electrocatalytic activity of the Ni-MOF flowers can be adjusted by doping Zn into the framework.

Endopolygalacturonase is encoded by a multigene family in the basidiomycete Chondrostereum purpureum.

The basidiomycete Chondrostereum purpureum produces several plant cell wall-degrading enzymes, including endopolygalacturonase (endoPG). Degenerate oligonucleotide primers were designed according to conserved regions of endoPG genes from various fungi, plants, and bacteria and used to amplify members of this gene family from C. purpureum. Four different amplification products showed significant similarity to known endoPGs and were used as hybridization probes to screen a library of genomic DNA sequences and to retrieve five full-length endoPG genes (epgA, epgB1, epgB2, epgC, and epgD). The identities between the deduced polypeptides for epgA, epgB1, epgC, and epgD ranged from 61.8 to 80.0%, while the deduced polypeptides for epgB1 and epgB2 shared 97.1% identity. Phylogenetic analysis suggested that the duplication of existing endoPG genes occurred after the divergence of the ascomycetes and basidiomycetes. C. purpureum is the first basidiomycete fungus for which the endoPG gene family has been described.