Enhancing MXene-based supercapacitors:Role of synthesis and 3D architectures

MXene has been the limelight for studies on electrode active materials,aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices.Despite its various desirable properties including intrinsic flexibility,high specific surface area,excellent metallic conductivity and unique abundance of surface functionalities,its full potential for electrochemical performance is hindered by the notorious restacking phenomenon of MXene nanosheets.Ascribed to its two-dimensional(2D)nature and surface functional groups,inevitable Van der Waals interactions drive the agglomeration of nanosheets,ultimately reducing the exposure of electrochemically active sites to the electrolyte,as well as severely lengthening electrolyte ion transport pathways.As a result,energy and power density deteriorate,limiting the application versatility of MXene-based supercapacitors.Constructing 3D architectures using 2D nanosheets presents as a straightforward yet ingenious approach to mitigate the fatal flaws of MXene.However,the sheer number of distinct methodologies reported,thus far,calls for a systematic review that unravels the rationale behind such 3D MXene structural designs.Herein,this review aims to serve this purpose while also scrutinizing the structure–property relationship to correlate such structural modifications to their ensuing electrochemical performance enhancements.Besides,the physicochemical properties of MXene play fundamental roles in determining the effective charge storage capabilities of 3D MXene-based electrodes.This largely depends on different MXene synthesis techniques and synthesis condition variations,hence,elucidated in this review as well.Lastly,the challenges and perspectives for achieving viable commercialization of MXene-based supercapacitor electrodes are highlighted.

Seismic Imaging and 3D Architecture of Yongle Atoll of the Xisha Archipelago, South China Sea

Yongle atoll in the Xisha(Paracel) Archipelago is an isolated carbonate platform developed on Precambrian metamorphic and Mesozoic volcanic rocks since the early Miocene. To identify the 3D stratigraphic architecture and evolution of this platform, 13 high-resolution seismic profiles and shallow-to-deep water multi-beam data were processed and analyzed to reveal seismic facies, sequence boundary reflectors, seismic units, and platform architecture. Nine types of seismic facies were recognized based on their geometry, which included seismic amplitude, continuity, and termination patterns;additionally, six reflections, i.e., Tg, T60, T50, T40, T30, and T20, were identified in the Cenozoic strata. Five seismic units, SQ1(lower Miocene), SQ2(middle Miocene), SQ3(upper Miocene), SQ4(Pliocene), and SQ5(Quaternary), were identified from bottom to top across the platform. The platform grew rapidly in the middle Miocene and backstepped in the late Miocene–Pliocene. Here, we discuss the developmental characteristics and evolution of the Yongle Atoll, in combination with drilling wells, which can be divided into four stages: the initiation stage in the early Miocene, the flourishing stage in the middle Miocene, the partial-drowning stage in the late Miocene–Pliocene, and modern atoll in the Quaternary.

3D MXene architectures as sulfur hosts for high-performance lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)are one of the most promising energy storage devices because of their high theoretical energy density;however,inherent issues including poor electrical conductivity and severe dissolution of S and its discharged products hinder their practical applications.MXenes have metallic conductivity,ultra-thin two-dimensional(2D)structures,rich surface functional groups,and macrostructural adjustability and have been widely used to design advanced sulfur hosts.3D network structures assembled by 2D MXene nanosheets have shown superior performance for improving reaction kinetics,accommodating and dispersing sulfur at the micro-/nanoscale,and capturing polysulfides due to their porous interconnected structure.Herein,the applications of MXene architectures related to 2D layered structures,3D multilayered structures,and 3D spherical structures as sulfur hosts are reviewed.The structure-performance relationship,challenges for current designs,and opportunities for future 3D architectures for LSBs are also analyzed.

A Porous 3D Supramolecular Architecture of Cd(II) Complex with Water Clusters as Pillars

A supramolecular complex of Cd（II） with 1D water tapes as pillars[Cd2（dpa）2（phen）2（H2O）2]·6H2O 1 （H2dpa = diphenic acid, phen = phenanthroline）, has been synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction analysis. The crystal is of triclinic, space group P1^- with a = 9.7029（4）, b = 11.9601（5）, c = 12.1788（4） A, α = 71.6990（10）, β = 71.8740（10）, γ = 74.4680（10）°, V = 1252.39（8） A^3, C52H48Cd2N4O16, Mr = 1209.76, Z= 1, Dc = 1.604 g/cm^3,μ = 0.925 mm^-1, F（000） = 612, R = 0.0679 and wR = 0.2514 for 3870 observed reflections （I 〉 2σ（I））. Two intramolecular Cd（II） centers of this complex are encircled by two dpa^2- ligands forming an 18-membered ring, which is further assembled into a pillared three-dimensional （3D） supramolecular architecture through the synergetic effect of intermolecular face-to-face π…π stacking and weak O-H…O hydrogen-bonding interactions. Moreover, this complex exhibits photoluminescence with the main emission bands located at about 456 nm upon excitation at 355 nm in the solid state at room temperature.

Architecture and Implementation of 3D Engine Based on WebGL

As the progress of 3D rendering technology and the changes of market demand, the 3D application has been widely used and reached as far as education, entertainment, medical treatment, city planning, military training and so on. Its trend is gradually changed from client to web, and so many people start to research the 3D graphics engine technology on the web. WebGL and HTML5 rise in recent years and WebGL solves two problems of interactive 3D application on the web perfectly. Firstly, it implements the interactive 3D web application by JavaScript without any browser plug-in components. Secondly, it makes graphics rendering using the underlying graphics hardware, which is united, standard and cross-platform OpenGL interface. However, it is very difficult for 3D application web programmer to understand multifarious details. Therefore, a 3D engine based on WebGL comes into being. The paper consults the existing 3D engine design idea, architecture and implementation experience, and designs a 3D graphics engine based on WebGL and Typescript.

3D Prussian blue/Pt decorated carbon nanofibers based screen-printed microchips for the ultrasensitive hydroquinone biosensing

Nowadays,water pollution has become more serious,greatly affecting human life and healthy.Electrochemical biosensor,a novel and rapid detection technique,plays an important role in the realtime and trace detection of water pollutants.However,the stability and sensitivity of electrochemical biosensors remain a great challenge for practical detections in real samples to the strong interferences derived from complex components and coagulation effects.In this work,we reported a novel threedimensional architecture of Prussian blue nanoparticles(PBNPs)/Pt nanoparticles(PtNPs)composite film,using 3 D interweaved carbon nanofibers as a supporting matrix,for the construction of screenprinted microchips-based biosensor.PtNPs with diameters of-2.5 nm was highly dispersed on the carbon nanofibers(CNFs)to build a 3 D skeleton nanostructure through a solvothermal reduction.Subsequently,uniform PBNPs were in-situ self-assembled on this skeleton to construct a 3 D architecture of PB/Pt-CNF composite film.Due to the synergistic effects derived from this special feature,the as-prepared hydroquinone(HQ)biosensor chips can synchronously promote both surface area and conductivity to greatly enhance the electrocatalysis from enzymatic reaction.This biosensor has exhibited a high sensitivity of 220.28μA·L·mmol^(-1)·cm^(-2) with an ultrawide linear range from 2.5μmol·L^(-1) to 1.45 mmol·L^(-1) at a low potential of 0.15 V,as well as the satisfactory reproducibility and usage stability.Besides,its accuracy was also verified in the assays of real water samples.It is highly expected that the 3 D PB/Pt-CNF based screen-printed microchips will have wide applications in dynamic monitoring and early warning of analytes in the various practical fields.

3D Interconnected MoO_2 Nanocrystals on Nickel Foam as Binder-free Anode for Li-ion Batteries

MoOnanocrystals(NCs) on Ni foam were simply synthesized via a facile hydrothermal method and a dip-coating method. It was worth noting that ultrafine interconnected MoOnanocrystals(about 10 nm) were uniformly anchored on Ni foam to fabricate a particular three-dimensional architecture, which may provide more active sites and shorter transmission pathways for lithium ions. As binder-free anode, MoONCs on Ni foam deliver a high initial discharge capacity of 990 mAh·gand retain a reversible capacity of 924 mAh· g(-1) after 100 cycles at a current density of 0.1 C. More importantly, when the current density returns from 2 C to 0.1 C, the capacity recovers to 910 mAh·g(-1)(about 92% of the original high capacity), suggesting excellent cycling stability and rate capability. The particular 3 D electrode as binder-free anode makes it a promising anode candidate for high-performance lithium-ion batteries.

3D Ultralight Hollow NiCo Compound@MXene Composites for Tunable and High-E cient Microwave Absorption

The 3D hollow hierarchi-cal architectures tend to be designed for inhibiting stack of MXene flakes to obtain satisfactory lightweight,high-e cient and broadband absorbers.Herein,the hollow NiCo compound@MXene networks were prepared by etching the ZIF 67 template and subsequently anchoring the Ti_(3)C_(2)Tx nanosheets through electrostatic self-assembly.The electromagnetic parameters and microwave absorption property can be distinctly or slightly regulated by adjusting the filler loading and decoration of Ti_(3)C_(2)Tx nanoflakes.Based on the synergistic e ectsof multi-components and special well-constructed structure,NiCo layered double hydroxides@Ti_(3)C_(2)Tx(LDHT-9)absorber remarkably achieves unexpected e ective absorption bandwidth(EAB)of 6.72 GHz with a thickness of 2.10 mm,covering the entire Ku-band.After calcination,transition metal oxide@Ti_(3)C_(2)Tx(TMOT-21)absorber near the percolation threshold possesses minimum reflection loss(RLmin)value of-67.22 dB at 1.70 mm within a filler loading of only 5 wt%.This work enlightens a simple strategy for constructing MXene-based composites to achieve high-e cient microwave absorbents with lightweight and tunable EAB.

Porous Carbon Architecture Assembled by Cross-Linked Carbon Leaves with Implanted Atomic Cobalt for High-Performance Li-S Batteries

The practical application of lithium-sulfur batteries is severely hampered by the poor conductivity,polysulfide shuttle effect and sluggish reaction kinetics of sulfur cathodes.Herein,a hierarchi-cally porous three-dimension(3D)carbon architecture assembled by cross-linked carbon leaves with implanted atomic Co-N4 has been deli-cately developed as an advanced sulfur host through a SiO_(2)-mediated zeolitic imidazolate framework-L(ZIF-L)strategy.The unique 3D architectures not only provide a highly conductive network for fast electron transfer and buffer the volume change upon lithiation-delithi-ation process but also endow rich interface with full exposure of Co-N4 active sites to boost the lithium polysulfides adsorption and conversion.Owing to the accelerated kinetics and suppressed shuttle effect,the as-prepared sulfur cathode exhibits a superior electrochemical perfor-mance with a high reversible specific capacity of 695 mAh g^(−1) at 5 C and a low capacity fading rate of 0.053%per cycle over 500 cycles at 1 C.This work may provide a promising solution for the design of an advanced sulfur-based cathode toward high-performance Li-S batteries.

3D Hierarchical Co–Al Layered Double Hydroxides with Long-Term Stabilities and High Rate Performances in Supercapacitors

Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co–Al-LDHs was improved. When used in supercapacitors, the obtained Co–Al-LDHs deliver a high specific capacitance of 838 Fg^(-1) at a current density of 1 Ag^(-1)and excellent rate performance(753 Fg^(-1) at 30 Ag^(-1) and 677 Fg^(-1) at 100 Ag^(-1)), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 Ag^(-1). This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.

Reorganization of 3D genome architecture provides insights into pathogenesis of early fatty liver disease in laying hens

Background Fatty liver disease causes huge economic losses in the poultry industry due to its high occurrence and lethality rate.Three-dimensional(3D)chromatin architecture takes part in disease processing by regulating tran-scriptional reprogramming.The study is carried out to investigate the alterations of hepatic 3D genome and H3K27ac profiling in early fatty liver(FLS)and reveal their effect on hepatic transcriptional reprogramming in laying hens.Results Results show that FLS model is constructed with obvious phenotypes including hepatic visible lipid deposi-tion as well as higher total triglyceride and cholesterol in serum.A/B compartment switching,topologically associat-ing domain(TAD)and chromatin loop changes are identified by high-throughput/resolution chromosome conforma-tion capture(HiC)technology.Targeted genes of these alternations in hepatic 3D genome organization significantly enrich pathways related to lipid metabolism and hepatic damage.H3K27ac differential peaks and differential expres-sion genes(DEGs)identified through RNA-seq analysis are also enriched in these pathways.Notably,certain DEGs are found to correspond with changes in 3D chromatin structure and H3K27ac binding in their promoters.DNA motif analysis reveals that candidate transcription factors are implicated in regulating transcriptional reprogram-ming.Furthermore,disturbed folate metabolism is observed,as evidenced by lower folate levels and altered enzyme expression.Conclusion Our findings establish a link between transcriptional reprogramming changes and 3D chromatin struc-ture variations during early FLS formation,which provides candidate transcription factors and folate as targets for FLS prevention or treatment.

Root architecture characteristics of plant inlay in live slope grating

In the experimental garden of the Department of Soil Bioengineering and Landscape Construction, University of Applied Life Sciences in Vienna, Austria, coarse root systems of three different brush species were completely excavated and semiutomatically digitized. The species were Lonicera xylosteum, Ligustrum vulgare and Euonymus europaeus. The 3-D root architectures reveal different growth strategies between species, which are related to ecological characteristics and physical soil properties. The root architecture of Lonicera xylosteum and Ligustrum vulgare, planted in the under layer of the live slope grading, where the soil is very tight and the soil water content and fertility are relatively low, is shallow. However, the root distribution of E. europaeus, planted in the middle layer, where environmental conditions are better, is deeper. Most of the root biomass of the three species is concentrated in the 0-30 cm soil layer. A quarter of the root biomass ofLigustrum vulgare is distributed in the upper layer of the plant inlay. E. europaeus has a relatively even distribution in the 30-0 cm and 60-90 cm soil layer.

Wear-resistant Ag-MAX phase 3D interpenetrating-phase composites:Processing,structure,and properties

Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments.The MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact materials.The biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact materials.Here,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) scaffolds.The mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural dimensions.The composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy methods.In particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic contents.The good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applications.

Recent Progress on Two-Dimensional Nanoflake Ensembles for Energy Storage Applications

The rational design and synthesis of two-dimensional(2D) nanoflake ensemble-based materials have garnered great attention owing to the properties of the components of these materials, such as high mechanical flexibility, high specific surface area, numerous active sites,chemical stability, and superior electrical and thermal conductivity. These properties render the 2D ensembles great choices as alternative electrode materials for electrochemical energy storage systems. More recently,recognition of the numerous advantages of these 2D ensemble structures has led to the realization that the performance of certain devices could be significantly enhanced by utilizing three-dimensional(3D) architectures that can furnish an increased number of active sites. The present review summarizes the recent progress in 2D ensemble-based materials for energy storage applications,including supercapacitors, lithium-ion batteries, and sodium-ion batteries. Further, perspectives relating to the challenges and opportunities in this promising research area are discussed.

In-situ assembly of 2D/3D porous nickel cobalt sulfide solid solution as superior pre-catalysts to boost multi-functional electrocatalytic oxidation

In this work,we fabricated an efficient pre-catalyst based on(Ni,Co)S2solid solution with hierarchical architecture and high porosity to boost urea oxidation reaction and electrocatalytic oxidation of organic small molecules.The interaction between Ni and Co can optimize the electronic structure,resulting in the improved conductivity and accelerated charge transfer rate.The 2D/3D architecture can enrich more active species and endow the mass and electron transport to facilitate the surface oxidation and the following catalytic process.Post-structure and catalytic characterizations confirm the surface oxidation of(Ni,Co)S_(2)during the stability test,and the in-situ formed Co(Ni)based(oxy)hydroxides exhibit superior catalytic activity and facilitated charge transfer ability.As a result,the optimal(Ni,Co)S_(2)solid solution pre-catalyst displays facilitated catalytic behavior and good stability for multifunctional electrocatalytic oxidation,in which a high conversion of benzyl alcohol(97.50%),a good selectivity to benzoic acid(93.78%)and a satisfied faraday efficiency(91.86%)can be achieved.

The dynamics of 3D chromatin architecture in mammalian preimplantation embryos

Subject Code:C06Research groups of Prof.Xie Wei(颉伟)at Tsinghua University published a research paper in Nature(2017,547:232—235)on July 13th,entitled“Allelic reprogramming of 3Dchromatin architecture during early mammalian development”with the support by the National Natural Science Foundation of China.

Three-dimensional architectures based on carbon nanotube bridged Ti_(2)C MXene nanosheets for Li-S batteries

Lithium-sulfur(Li-S)batteries are promising candidates for high density electrochemical energy storage systems.However,the poor conductivity of S and the shuttle effect of polysulfides are a bottleneck to practical applications.Herein,a three-dimensional architecture,based on carbon nanotube(CNT)bridged Ti_(2)C MXene nanosheets,was constructed as a sulfur host.This architecture was based on Ti atoms,which can chemically absorb polysulfides.The CNTs are highly conductive and intercalate into the MXene nanosheets to prevent their stacking and construct an interspace for polysulfides.This hybrid,as a host of S,can effectively alleviate the shuttle effect through a combination of physical confinement and chemical adsorption.This resulted in an open internal space,which served as a cathode for the loaded S to promote electron transport and enhance electrochemical kinetics of the polysulfide conversion in Li-S batteries.

Fabrication of the ZnO/NiO p–n junction foam for the enhanced sensing performance

P-Type NiO foam with rough nanostructured surface was prepared by the surface treatment of Ni foam,and then it was decorated with n-type ZnO nanopyramids to construct a 3D p–n junction foam. The p–n junction foam was used for electrochemical detection of dopamine and the sensing performance was improved significantly compared with the single NiO and ZnO. High sensitivity（171 mμA/mmol/L）, fast response（2 s）, excellent selectivity and stability were achieved. It was attributed to the introduction of numerous p–n junction interfaces, the interfacial potential barrier played as a tuning factor for the electrochemical determination of dopamine. The results demonstrated it would be an important way to improve the biosensing performance by introducing the p–n junction interfaces.

Three-dimensional interconnected Ni（Fe）OxHy nanosheets on stainless steel mesh as a robust integrated oxygen evolution electrode

The development of an electrocatalyst based on abundant elements for the oxygen evolution reaction （OER） is important for water splitting associated with renewable energy sources. In this study, we develop an interconnected Ni（Fe）OxHy nanosheet array on a stainless steel mesh （SSNNi） as an integrated OER electrode, without using any polymer binder. Benefiting from the well- defined three-dimensional （3D） architecture with highly exposed surface area, intimate contact between the active species and conductive substrate improved electron and mass transport capacity, facilitated electrolyte penetration, and improved mechanical stability. The SSNNi electrode also has excellent OER performance, including low overpotential, a small Tafel slope, and long-term durability in the alkaline electrolyte, making it one of the most promising OER electrodes developed.

Chromatin architectural alterations due to null mutation of a major CG methylase in rice

Associations between 3D chromatin architectures and epigenetic modifications have been characterized in animals.However,any impact of DNA methylation on chromatin architecture in plants is understudied,which is confined to Arabidopsis thaliana.Because plant species differ in genome size,composition,and overall chromatin packing,it is unclear to what extent findings from A.thaliana hold in other species.Moreover,the incomplete chromatin architectural profiles and the low-resolution high-throughput chromosome conformation capture(Hi-C)data from A.thaliana have hampered characterizing its subtle chromatin structures and their associations with DNA methylation.We constructed a high-resolution Hi-C interaction map for the null OsMET1-2(the major CG methyltransferase in rice)mutant(osmet1-2)and isogenic wild-type rice(WT).Chromatin structural changes occurred in osmetl-2,including intra-/inter-chromosomal interactions,compartment transition,and topologically associated domains(TAD)variations.Our findings provide novel insights into the potential function of DNA methylation in TAD formation in rice and confirmed DNA methylation plays similar essential roles in chromatin packing in A,thaliana and rice.