Metal-organic framework(MOF)and covalent organic framework(COF)are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features,such as large surface area,tunable pore size,and ...Metal-organic framework(MOF)and covalent organic framework(COF)are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features,such as large surface area,tunable pore size,and functional surfaces,which have significant values in various application areas.The emerging 3D printing technology further provides MOF and COFs(M/COFs)with higher designability of their macrostructure and demonstrates large achievements in their performance by shaping them into advanced 3D monoliths.However,the currently available 3D printing M/COFs strategy faces a major challenge of severe destruction of M/COFs’microstructural features,both during and after 3D printing.It is envisioned that preserving the microstructure of M/COFs in the 3D-printed monolith will bring a great improvement to the related applications.In this overview,the 3D-printed M/COFs are categorized into M/COF-mixed monoliths and M/COF-covered monoliths.Their differences in the properties,applications,and current research states are discussed.The up-to-date advancements in paste/scaffold composition and printing/covering methods to preserve the superior M/COF microstructure during 3D printing are further discussed for the two types of 3D-printed M/COF.Throughout the analysis of the current states of 3D-printed M/COFs,the expected future research direction to achieve a highly preserved microstructure in the 3D monolith is proposed.展开更多
Nanoscale light sources with high speed of electrical modulation and low energy consumption are key components for nanophotonics and optoelectronics.The record-high carrier mobility and ultrafast carrier dynamics of g...Nanoscale light sources with high speed of electrical modulation and low energy consumption are key components for nanophotonics and optoelectronics.The record-high carrier mobility and ultrafast carrier dynamics of graphene make it promising as an atomically thin light emitter which can be further integrated into arbitrary platforms by van der Waals forces.However,due to the zero bandgap,graphene is difficult to emit light through the interband recombination of carriers like conventional semiconductors.Here,we demonstrate ultrafast thermal light emitters based on suspended graphene/hexagonal boron nitride(Gr/hBN)heterostructures.Electrons in biased graphene are significantly heated up to 2800 K at modest electric fields,emitting bright photons from the near-infrared to the visible spectral range.By eliminating the heat dissipation channel of the substrate,the radiation efficiency of the suspended Gr/hBN device is about two orders of magnitude greater than that of graphene devices supported on SiO2or hBN.Wefurther demonstrate that hot electrons and low-energy acoustic phonons in graphene are weakly coupled to each other and are not in full thermal equilibrium.Direct cooling ofhigh-temperature hot electrons to low-temperature acoustic phonons is enabled by the significant near-field heat transfer at the highly localized Gr/hBN interface,resulting in ultrafast thermal emission with up to 1 GHz bandwidth under electrical excitation.It is found thatsuspending the Gr/hBN heterostructures on the SiO2trenches significantly modifies the light emission due to the formation of the optical cavity and showed a~440%enhancement inintensity at the peak wavelength of 940 nm compared to the black-body thermal radiation.The demonstration of electrically driven ultrafast light emission from suspended Gr/hBNheterostructures sheds the light on applications of graphene heterostructures in photonicintegrated circuits,such as broadband light sources and ultrafast thermo-optic phase modulators.展开更多
Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on des...Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on designing electrocatalysts with high activity and selectivity.The detailed correlation between catalyst properties and NO3-RR kinetics,nevertheless,is still not fully understood.In this work,we modulate the surface oxygen species of Cu_(2)O via facet engineering,and systematically study the impact of these oxygen species on the NO_(3)^(-)RR activity.Combining advanced spectroscopic techniques,densi ty fu n ctional theory calculations and molecular dynamics simulations,we find that while oxygen vacancies on Cu_(2)O(111) surface promote the adsorption of reactants and reaction intermediates,hydroxyl groups effectively inhibit the side reaction of hydrogen evolution and facilitate the hydrogenation process of NO3-RR.These two effects work in concert to render Cu_(2)O(111) facet the highest NO3-RR activity relative to those from other facets.Our study provides critical insights into the synergistic effect of exposed facets and surface oxygen species on heterogeneous catalysis,and offers a generalizable,facet engineeringbased strategy for improving the performance of a variety of electrocatalysts important for renewable energy conversion.展开更多
Carbon nanotubes (CNTs) and graphene have attracted great attention since decades ago because of their interesting structure and properties and important application in many areas. They can have high conductivity, hig...Carbon nanotubes (CNTs) and graphene have attracted great attention since decades ago because of their interesting structure and properties and important application in many areas. They can have high conductivity, high specific surface area, high transparency in the visible range and high mechanical flexibility. They have important application in energy conversion systems including solar cells and fuel cells. They have been extensively studied as the transparent electrode and interfacial materials of organic solar cells (OSCs) and perovskite solar cells (PSCs). They are also used as the catalytic counter electrode of dye-sensitized solar cells (DSSCs). In addition, graphene oxide (GO) is exploited as an auxiliary binder of TiO2 paste for the mesoporous TiO2 layer of DSSCs, and GO and functionalized CNTs are adopted as gelators of gel electrolyte for quasi-solid state DSSCs. CNTs and graphene also have important application in fuel cells. They can be used as catalyst support for the oxidation of fuels or oxygen reduction reaction (ORR). CNTs and graphene, particularly when doped with nitrogen, can be directly used metal-free catalysts. This article provides a brief review on the application of CNTs and graphene in OSCs, PSCs, DSSCs and fuel cells.展开更多
Flexible perovskite solar cells(FPSCs) have attracted enormous interest in wearable and portable electronics due to their high power-per-weight and low cost. Flexible and efficient perovskite solar cells require the d...Flexible perovskite solar cells(FPSCs) have attracted enormous interest in wearable and portable electronics due to their high power-per-weight and low cost. Flexible and efficient perovskite solar cells require the development of flexible electrodes compatible with the optoelectronic properties of perovskite. In this review, the recent progress of flexible electrodes used in FPSCs is comprehensively reviewed. The major features of flexible transparent electrodes, including transparent conductive oxides, conductive polymer, carbon nanomaterials and nanostructured metallic materials are systematically compared. And the corresponding modification strategies and device performance are summarized. Moreover, flexible opaque electrodes including metal films, opaque carbon materials and metal foils are critically assessed. Finally, the development directions and difficulties of flexible electrodes are given.展开更多
A coercivity as large as 2.4 kOe has been achieved in the Ni/NiO composite film after an annealing under a magnetic field of 10 kOe and an O_2 partial pressure of 0.001 torr.The coercivity was attributed to the strong...A coercivity as large as 2.4 kOe has been achieved in the Ni/NiO composite film after an annealing under a magnetic field of 10 kOe and an O_2 partial pressure of 0.001 torr.The coercivity was attributed to the strong exchange coupling of Ni and NiO.Small grain size of Ni and NiO was observed after the post-annealing.The enhanced coercivity is probably associated with the domain wall pinning by local energy minima,the distribution of Ni and NiO,and the domain structure in the interface of Ni/NiO generated under the presence of the magnetic field during the post-annealing.展开更多
Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically...Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.展开更多
As one of the essential components for flexible electronics,flexible electrochemical energy storage(EES)has garnered extensive interests at all levels of materials,devices,and systems.The successful implementation of ...As one of the essential components for flexible electronics,flexible electrochemical energy storage(EES)has garnered extensive interests at all levels of materials,devices,and systems.The successful implementation of high-performance flexible EES devices relies on exploring of suitable electrode/electrolyte materials that have both superior electrochemical and mechanical properties.For this function,one-dimensional electrospun nanofibers have emerged as a class of promising building blocks for the key components of flexible EES devices.In this overview,the fundamental principles and technical advances of electrospinning are examined,for both their successes and challenges in controllable fabrication of nanofibers with the desirable chemical compositions,micro/meso-/nanostructures,and therefore resultant properties.The advances in applications of electrospun nanofibers for various key flexible EES devices are critically looked into,including those in supercapacitors,metal-ion batteries,and metal-air batteries.The existing challenges and prospects of these electrospun nanofiber-based flexible EES are discussed,aiming to inspire continued efforts in developing the optimal high-performance and low cost flexible EES devices for long-awaited practical applications.展开更多
Mott insulator material,as a kind of strongly correlated electronic system with the characteristic of a drastic change in electrical conductivity,shows excellent application prospects in neuromorphological calculation...Mott insulator material,as a kind of strongly correlated electronic system with the characteristic of a drastic change in electrical conductivity,shows excellent application prospects in neuromorphological calculations and has attracted significant attention in the scientific community.Especially,computing systems based on Mott insulators can overcome the bottleneck of separated data storage and calculation in traditional artificial intelligence systems based on the von Neumann architecture,with the potential to save energy,increase operation speed,improve integration,scalability,and three-dimensionally stacked,and more suitable to neuromorphic computing than a complementary metal-oxide-semiconductor.In this review,we have reviewed Mott insulator materials,methods for driving Mott insulator transformation(pressure-,voltage-,and temperature-driven approaches),and recent relevant applications in neuromorphic calculations.The results in this review provide a path for further study of the applications in neuromorphic calculations based on Mott insulator materials and the related devices.展开更多
Promising room-temperature sodium-sulfur(RT Na-S)battery systems rely on purposely designed highperforming and low-cost electrode materials.Nevertheless,there are the challenges of irreversible dissolution and slow re...Promising room-temperature sodium-sulfur(RT Na-S)battery systems rely on purposely designed highperforming and low-cost electrode materials.Nevertheless,there are the challenges of irreversible dissolution and slow redox kinetics of NaPSs in the complete discharge of sulfur capacity.Herein,engineered CoMoO_(4)in reduced graphene oxide(CoMoO_(4)@rGO)is reported as a class of superior cathode hosts for RT Na-S batteries.The CoMoO_(4)@rGO matrix is designed to facilitate the reversible sodiation and desodiation of sulfur,considering the strong chemisorption between sulfur(and short-chain sodium sulfides)and CoMoO_(4),which alleviates the shuttle effect of sodium sulfides and accelerates the electrochemical reaction rate at RT.The obtained S/CoMoO_(4)@rGO cathode with~52%S loading exhibits a high capacity of520.1 mA h g^(-1)after 100 cycles at 0.1 A g^(-1).Moreover,an enhanced long-term performance at high current densities(212.2 mA h g^(-1)at 4 A g^(-1)over 1000 cycles)with high Coulombic efficiency(~100%)is also achieved.This work demonstrates a novel multifunctional additive for RT Na-S battery cathodes,which is expected to promote the long-waited development towards practical applications of RT Na-S batteries.展开更多
A round 60% of useful energy is wasted in industry, homes, or transportation. Therefore, there has been increasing attention on thermoelectric materials for their ability to harvest waste heat into useful energy. The ...A round 60% of useful energy is wasted in industry, homes, or transportation. Therefore, there has been increasing attention on thermoelectric materials for their ability to harvest waste heat into useful energy. The efficiency of a thermoelectric material depends on its electrical conductivity, Seebeck coefficient, and thermal conductivity in a conflicting manner which results in efficiency optimization challenges. Single crystals and polycrystalline layered materials have comparatively better thermoelectric and mechanical properties in a certain direction. Texture engineering is a special strategy that allows the exploitation of superior material properties in a specific direction. Texturing could be achieved by various sintering and deformation methods, which yield defects improving thermoelectric and mechanical properties. The results show that for(Bi,Sb)_(2)Te_(3), Bi_(2)(Se,Te)_(3), C uSbSe_(2), and SnSe, significant enhancement in the thermoelectric figure of merit is achieved by enhancing the preferred orientation. Texture engineering provides a wide range of strategies to elevate the zT of anisotropic materials to values comparable to those of their single crystalline counterparts.展开更多
There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processe...There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.展开更多
Aqueous ammonium-ion(NH_(4)^(+))hybrid supercapacitor(AA-HSC),as a new type of energy storage device with great potential,is in the initial stage of rapid development.Based on its special energy storage mechanism,expl...Aqueous ammonium-ion(NH_(4)^(+))hybrid supercapacitor(AA-HSC),as a new type of energy storage device with great potential,is in the initial stage of rapid development.Based on its special energy storage mechanism,exploiting novel NH_(4)^(+)-hostingmaterials is still a great challenge.Herein,vanadium oxide hydration(VOH)tuned by interlayer engineering of K+/PANI co-intercalation,named KVO/PANI,is designed for AA-HSC.Intercalated PANI can shield interaction between NH_(4)^(+)and V–O layers to some extent and enlarge interlayer space,which improves the efficiency of reversible NH_(4)^(+)(de)insertion.However,K+enhances redox activity and electronic conductivity.The synergistic effect of co-intercalation optimizes intercalation pseudocapacitive behavior during the(de)ammonization process,which is reported in NH_(4)^(+)storage for the first time.Theoretical calculations reveal that the lowered electron transport barrier and enhanced electronic conductivity improveNH_(4)^(+)kinetics and exhibit high capacitance for charge storage.The KVO/PANI can deliver the specific capacitance of 340 F g^(−1) at 0.5 A g^(−1) and retain 177 F g^(−1) at 10 A g^(−1).Pairing with activated carbon,the AA-HSC can achieve a decent energy density of 31.8 Wh kg^(−1).This work gives inorganic/organic co-intercalation that can enhance the NH_(4)^(+)storage of VOH by interlayer engineering.The strategy can be used to design other materials for aqueous energy storage systems.展开更多
2D materials are promising candidates as nonlinear optical components for on-chip devices due to their ultrathin structure. In general, their nonlinear optical responses are inherently weak due to the short interactio...2D materials are promising candidates as nonlinear optical components for on-chip devices due to their ultrathin structure. In general, their nonlinear optical responses are inherently weak due to the short interaction thickness with light. Recently, there has been great interest in using quasi-bound states in the continuum (q-BICs) of dielectric metasurfaces, which are able to achieve remarkable optical near-field enhancement for elevating the second harmonic generation (SHG) emission from 2D materials. However, most studies focus on the design of combining bulk dielectric metasurfaces with unpatterned 2D materials, which suffer considerable radiation loss and limit near-field enhancement by high-quality q-BIC resonances. Here, we investigate the dielectric metasurface evolution from bulk silicon to monolayer molybdenum disulfide (MoS2), and discover the critical role of meta-atom thickness design on enhancing near-field effects of two q-BIC modes. We further introduce the strongcoupling of the two q-BIC modes by oblique incidence manipulation, and enhance the localized optical field on monolayer MoS2dramatically. In the ultraviolet and visible regions, the MoS2SHG enhancement factor of our design is 105times higher than that of conventional bulk metasurfaces, leading to an extremely high nonlinear conversion efficiency of 5.8%. Our research will provide an important theoretical guide for the design of high-performance nonlinear devices based on 2D materials.展开更多
The emergence of van der Waals(vdW)materials resulted in the discovery of their high optical,mechanical,and electronic anisotropic properties,immediately enabling countless novel phenomena and applications.Such succes...The emergence of van der Waals(vdW)materials resulted in the discovery of their high optical,mechanical,and electronic anisotropic properties,immediately enabling countless novel phenomena and applications.Such success inspired an intensive search for the highest possible anisotropic properties among vdW materials.Furthermore,the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches.Here,we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization.Using our approach,we found As2S3 as a highly anisotropic vdW material.It demonstrates high in-plane optical anisotropy that is~20%larger than for rutile and over two times as large as calcite,high refractive index,and transparency in the visible range,overcoming the century-long record set by rutile.Given these benefits,As2S3 opens a pathway towards nextgeneration nanophotonics as demonstrated by an ultrathin true zero-order quarter-wave plate that combines classical and the Fabry–Pérot optical phase accumulations.Hence,our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.展开更多
Rapid and accurate chemical composition identification is critically important in chemistry.While it can be achieved with optical absorption spectrometry by comparing the experimental spectra with the reference data w...Rapid and accurate chemical composition identification is critically important in chemistry.While it can be achieved with optical absorption spectrometry by comparing the experimental spectra with the reference data when the chemical compositions are simple,such application is limited in more complicated scenarios especially in nano-scale research.This is due to the difficulties in identifying optical absorption peaks(i.e.,from“featureless”spectra)arose from the complexity.In this work,using the ultraviolet-visible(UV-Vis)absorption spectra of metal nanoclusters(NCs)as a demonstration,we develop a machine-learningbased method to unravel the compositions of metal NCs behind the“featureless”spectra.By implementing a one-dimensional convolutional neural network,good matches between prediction results and experimental results and low mean absolute error values are achieved on these optical absorption spectra that human cannot interpret.This work opens a door for the identification of nanomaterials at molecular precision from their optical properties,paving the way to rapid and high-throughput characterizations.展开更多
Understanding the thermodynamic properties of electrolyte solutions is of vital importance for a myriad of physiological and technological applications.The mean activity coefficientγ±is associated with the devia...Understanding the thermodynamic properties of electrolyte solutions is of vital importance for a myriad of physiological and technological applications.The mean activity coefficientγ±is associated with the deviation of an electrolyte solution from its ideal behavior and may be obtained by combining the Debye-Hückel(DH)and Born(B)equations.However,the DH and B equations depend on the concentration and temperature-dependent static permittivity of the solutionεr(c,T)and the size of the solvated ions ri,whose experimental data is often not available.Here,we use a combination of molecular dynamics and density functional theory to predictεr(c,T)and ri,which enables us to apply the DH and B equations to any technologically relevant aqueous and nonaqueous electrolyte at any concentration and temperature of interest.展开更多
Rechargeable batteries of high energy density and overall performance are becoming a critically important technology in the rapidly changing society of the twenty-first century.While lithium-ion batteries have so far ...Rechargeable batteries of high energy density and overall performance are becoming a critically important technology in the rapidly changing society of the twenty-first century.While lithium-ion batteries have so far been the dominant choice,numerous emerging applications call for higher capacity,better safety and lower costs while maintaining sufficient cyclability.The design space for potentially better alternatives is extremely large,with numerous new chemistries and architectures being simultaneously explored.These include other insertion ions(e.g.sodium and numerous multivalent ions),conversion electrode materials(e.g.silicon,metallic anodes,halides and chalcogens)and aqueous and solid electrolytes.However,each of these potential“beyond lithium-ion”alternatives faces numerous challenges that often lead to very poor cyclability,especially at the commercial cell level,while lithium-ion batteries continue to improve in performance and decrease in cost.This review examines fundamental principles to rationalise these numerous developments,and in each case,a brief overview is given on the advantages,advances,remaining challenges preventing cell-level implementation and the state-of-the-art of the solutions to these challenges.Finally,research and development results obtained in academia are compared to emerging commercial examples,as a commentary on the current and near-future viability of these“beyond lithium-ion”alternatives.展开更多
Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of recha...Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.展开更多
MOFs are among the most popular precursors and templates for deriving various porous materials,where the derivatives can inherit a large surface area,abundant active sites for targeted functionalities and a high degre...MOFs are among the most popular precursors and templates for deriving various porous materials,where the derivatives can inherit a large surface area,abundant active sites for targeted functionalities and a high degree of porosity inherited from their parent MOFs.Those unique structural features make them promising candidates in multiple applications.More interestingly,the structure and properties of these MOF derivatives can be modulated by the choice of the parent MOFs and the design in the conversion process.In this overview,the transformation pathways from MOFs into their porous derivatives,the principles underlying these transformations,and the behavior of the MOF components in the transition process are discussed.Recently,there has been tremendous progress in preserving and enhancing the surface area,the amount of active sites and the level of porosity of the MOF-derived materials for targeted applications,from the perspectives of both customizing the parent MOFs and tailoring the transformation process.To develop the rationally designed MOF-derived materials and thus to elucidate the precursor-process-product correlations,some typical examples of the MOF derivatives applied in electrochemical energy storage and conversion,water treatment,gas sensing,and biomedicine are discussed to demonstrate the effectiveness of the key design strategies.展开更多
基金the support by National Research Foundation of Singapore(NRF,Project:NRF-CRP262021RS-0002),for research conducted at the National University of Singapore(NUS)。
文摘Metal-organic framework(MOF)and covalent organic framework(COF)are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features,such as large surface area,tunable pore size,and functional surfaces,which have significant values in various application areas.The emerging 3D printing technology further provides MOF and COFs(M/COFs)with higher designability of their macrostructure and demonstrates large achievements in their performance by shaping them into advanced 3D monoliths.However,the currently available 3D printing M/COFs strategy faces a major challenge of severe destruction of M/COFs’microstructural features,both during and after 3D printing.It is envisioned that preserving the microstructure of M/COFs in the 3D-printed monolith will bring a great improvement to the related applications.In this overview,the 3D-printed M/COFs are categorized into M/COF-mixed monoliths and M/COF-covered monoliths.Their differences in the properties,applications,and current research states are discussed.The up-to-date advancements in paste/scaffold composition and printing/covering methods to preserve the superior M/COF microstructure during 3D printing are further discussed for the two types of 3D-printed M/COF.Throughout the analysis of the current states of 3D-printed M/COFs,the expected future research direction to achieve a highly preserved microstructure in the 3D monolith is proposed.
基金supported by the National Natural Science Foundation of China(Nos.12174444 and 52202195)the Natural Science Foundation of Hunan Province(2020RC3032)。
文摘Nanoscale light sources with high speed of electrical modulation and low energy consumption are key components for nanophotonics and optoelectronics.The record-high carrier mobility and ultrafast carrier dynamics of graphene make it promising as an atomically thin light emitter which can be further integrated into arbitrary platforms by van der Waals forces.However,due to the zero bandgap,graphene is difficult to emit light through the interband recombination of carriers like conventional semiconductors.Here,we demonstrate ultrafast thermal light emitters based on suspended graphene/hexagonal boron nitride(Gr/hBN)heterostructures.Electrons in biased graphene are significantly heated up to 2800 K at modest electric fields,emitting bright photons from the near-infrared to the visible spectral range.By eliminating the heat dissipation channel of the substrate,the radiation efficiency of the suspended Gr/hBN device is about two orders of magnitude greater than that of graphene devices supported on SiO2or hBN.Wefurther demonstrate that hot electrons and low-energy acoustic phonons in graphene are weakly coupled to each other and are not in full thermal equilibrium.Direct cooling ofhigh-temperature hot electrons to low-temperature acoustic phonons is enabled by the significant near-field heat transfer at the highly localized Gr/hBN interface,resulting in ultrafast thermal emission with up to 1 GHz bandwidth under electrical excitation.It is found thatsuspending the Gr/hBN heterostructures on the SiO2trenches significantly modifies the light emission due to the formation of the optical cavity and showed a~440%enhancement inintensity at the peak wavelength of 940 nm compared to the black-body thermal radiation.The demonstration of electrically driven ultrafast light emission from suspended Gr/hBNheterostructures sheds the light on applications of graphene heterostructures in photonicintegrated circuits,such as broadband light sources and ultrafast thermo-optic phase modulators.
基金supported by the Guangdong Provincial Natural Science Foundation,China(2021A1515012330)the National Natural Science Foundation of China(11975102)+2 种基金the State Key Laboratory of Pulp and Paper Engineering(2022PY03)the Guangdong Pearl River Talent Program,China(2017GC010281)supported by ME2 project under contract from the National Natural Science Foundation of China(11227902)。
文摘Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on designing electrocatalysts with high activity and selectivity.The detailed correlation between catalyst properties and NO3-RR kinetics,nevertheless,is still not fully understood.In this work,we modulate the surface oxygen species of Cu_(2)O via facet engineering,and systematically study the impact of these oxygen species on the NO_(3)^(-)RR activity.Combining advanced spectroscopic techniques,densi ty fu n ctional theory calculations and molecular dynamics simulations,we find that while oxygen vacancies on Cu_(2)O(111) surface promote the adsorption of reactants and reaction intermediates,hydroxyl groups effectively inhibit the side reaction of hydrogen evolution and facilitate the hydrogenation process of NO3-RR.These two effects work in concert to render Cu_(2)O(111) facet the highest NO3-RR activity relative to those from other facets.Our study provides critical insights into the synergistic effect of exposed facets and surface oxygen species on heterogeneous catalysis,and offers a generalizable,facet engineeringbased strategy for improving the performance of a variety of electrocatalysts important for renewable energy conversion.
基金financially supported by a research grant from the Ministry of Education - Singapore (R-284-000-147-112)
文摘Carbon nanotubes (CNTs) and graphene have attracted great attention since decades ago because of their interesting structure and properties and important application in many areas. They can have high conductivity, high specific surface area, high transparency in the visible range and high mechanical flexibility. They have important application in energy conversion systems including solar cells and fuel cells. They have been extensively studied as the transparent electrode and interfacial materials of organic solar cells (OSCs) and perovskite solar cells (PSCs). They are also used as the catalytic counter electrode of dye-sensitized solar cells (DSSCs). In addition, graphene oxide (GO) is exploited as an auxiliary binder of TiO2 paste for the mesoporous TiO2 layer of DSSCs, and GO and functionalized CNTs are adopted as gelators of gel electrolyte for quasi-solid state DSSCs. CNTs and graphene also have important application in fuel cells. They can be used as catalyst support for the oxidation of fuels or oxygen reduction reaction (ORR). CNTs and graphene, particularly when doped with nitrogen, can be directly used metal-free catalysts. This article provides a brief review on the application of CNTs and graphene in OSCs, PSCs, DSSCs and fuel cells.
基金financially supported by the National Natural Science Foundation of China(52192610)the National Key Research and Development Program of China(Grant 2021YFA0715600)+1 种基金the Key Research and Development Program of Shaanxi Province(Grant 2020GY-310)the Fundamental Research Funds for the Central Universities and the Innovation Fund of Xidian University。
文摘Flexible perovskite solar cells(FPSCs) have attracted enormous interest in wearable and portable electronics due to their high power-per-weight and low cost. Flexible and efficient perovskite solar cells require the development of flexible electrodes compatible with the optoelectronic properties of perovskite. In this review, the recent progress of flexible electrodes used in FPSCs is comprehensively reviewed. The major features of flexible transparent electrodes, including transparent conductive oxides, conductive polymer, carbon nanomaterials and nanostructured metallic materials are systematically compared. And the corresponding modification strategies and device performance are summarized. Moreover, flexible opaque electrodes including metal films, opaque carbon materials and metal foils are critically assessed. Finally, the development directions and difficulties of flexible electrodes are given.
文摘A coercivity as large as 2.4 kOe has been achieved in the Ni/NiO composite film after an annealing under a magnetic field of 10 kOe and an O_2 partial pressure of 0.001 torr.The coercivity was attributed to the strong exchange coupling of Ni and NiO.Small grain size of Ni and NiO was observed after the post-annealing.The enhanced coercivity is probably associated with the domain wall pinning by local energy minima,the distribution of Ni and NiO,and the domain structure in the interface of Ni/NiO generated under the presence of the magnetic field during the post-annealing.
基金sponsored by Shanghai Pujiang Program(No.19PJ1405200)the Startup Fund for Youngman Research at SJTU(SFYR at SJTU,No.WF220516003)。
文摘Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.
基金the financial supports by National Natural Science Foundation of China(Grant No.51902265)Fundamental Research Funds for the Central Universities,Key Research and Development Program of Shaanxi(No.2020KWZ-001)Project for graduate Innovation team of Northwestern Polytechnical University
文摘As one of the essential components for flexible electronics,flexible electrochemical energy storage(EES)has garnered extensive interests at all levels of materials,devices,and systems.The successful implementation of high-performance flexible EES devices relies on exploring of suitable electrode/electrolyte materials that have both superior electrochemical and mechanical properties.For this function,one-dimensional electrospun nanofibers have emerged as a class of promising building blocks for the key components of flexible EES devices.In this overview,the fundamental principles and technical advances of electrospinning are examined,for both their successes and challenges in controllable fabrication of nanofibers with the desirable chemical compositions,micro/meso-/nanostructures,and therefore resultant properties.The advances in applications of electrospun nanofibers for various key flexible EES devices are critically looked into,including those in supercapacitors,metal-ion batteries,and metal-air batteries.The existing challenges and prospects of these electrospun nanofiber-based flexible EES are discussed,aiming to inspire continued efforts in developing the optimal high-performance and low cost flexible EES devices for long-awaited practical applications.
基金This work was financially supported by the National Key Research&Development Plan“Nano Frontier”Key Special Project(No.2021YFA1200502)Cultivation projects of national major Research&Development project(No.92164109)+11 种基金the National Natural Science Foundation of China(Nos.61874158,62004056,and 62104058)Special project of strategic leading science and technology of Chinese Academy of Sciences(No.XDB44000000-7)Hebei Basic Research Special Key Project(No.F2021201045)Support Program for the Top Young Talents of Hebei Province(No.70280011807)Supporting Plan for 100 Excellent Innovative Talents in Colleges and Universities of Hebei Province(No.SLRC2019018)Interdisciplinary Research Program of Natural Science of Hebei University(No.DXK202101)Institute of Life Sciences and Green Development(No.521100311)Natural Science Foundation of Hebei Province(Nos.F2022201054 and F2021201022)Outstanding Young Scientific Research and Innovation Team of Hebei University(No.605020521001)Special Support Funds for National High Level Talents(No.041500120001)Advanced Talents Incubation Program of the Hebei University(Nos.521000981426,521100221071,and 521000981363)Funded by Science and Technology Project of Hebei Education Department(Nos.QN2020178 and QN2021026).
文摘Mott insulator material,as a kind of strongly correlated electronic system with the characteristic of a drastic change in electrical conductivity,shows excellent application prospects in neuromorphological calculations and has attracted significant attention in the scientific community.Especially,computing systems based on Mott insulators can overcome the bottleneck of separated data storage and calculation in traditional artificial intelligence systems based on the von Neumann architecture,with the potential to save energy,increase operation speed,improve integration,scalability,and three-dimensionally stacked,and more suitable to neuromorphic computing than a complementary metal-oxide-semiconductor.In this review,we have reviewed Mott insulator materials,methods for driving Mott insulator transformation(pressure-,voltage-,and temperature-driven approaches),and recent relevant applications in neuromorphic calculations.The results in this review provide a path for further study of the applications in neuromorphic calculations based on Mott insulator materials and the related devices.
基金the support of the National Natural Science Foundation of China(51971146,51971147,52171218 and 52271222)the Shanghai Municipal Science and Technology Commission(21010503100 and 20ZR1438400)+3 种基金the Innovation Program of Shanghai Municipal EducationCommission(No.2019-01-07-00-07-E00015)the Shanghai Rising-Star Program(20QA1407100 and Yangfan Special Project:23YF1428900)the support of the Advanced Research and Technology Innovation Centre(ARTIC,Project Number ADT-RP2/A0005947-32-00)for research conducted by John Wang’s group。
文摘Promising room-temperature sodium-sulfur(RT Na-S)battery systems rely on purposely designed highperforming and low-cost electrode materials.Nevertheless,there are the challenges of irreversible dissolution and slow redox kinetics of NaPSs in the complete discharge of sulfur capacity.Herein,engineered CoMoO_(4)in reduced graphene oxide(CoMoO_(4)@rGO)is reported as a class of superior cathode hosts for RT Na-S batteries.The CoMoO_(4)@rGO matrix is designed to facilitate the reversible sodiation and desodiation of sulfur,considering the strong chemisorption between sulfur(and short-chain sodium sulfides)and CoMoO_(4),which alleviates the shuttle effect of sodium sulfides and accelerates the electrochemical reaction rate at RT.The obtained S/CoMoO_(4)@rGO cathode with~52%S loading exhibits a high capacity of520.1 mA h g^(-1)after 100 cycles at 0.1 A g^(-1).Moreover,an enhanced long-term performance at high current densities(212.2 mA h g^(-1)at 4 A g^(-1)over 1000 cycles)with high Coulombic efficiency(~100%)is also achieved.This work demonstrates a novel multifunctional additive for RT Na-S battery cathodes,which is expected to promote the long-waited development towards practical applications of RT Na-S batteries.
基金support from the A*STAR’s Science and Engineering Research CouncilSustainable Hybrid Lighting System for Controlled Environment Agriculture Program: A19D9a0096+1 种基金Singapore MOE AcRF Tier 2 under Grant (No.2018-T2-1-010)funding from the A*STAR’s Career Development Award (No.C210112022)。
文摘A round 60% of useful energy is wasted in industry, homes, or transportation. Therefore, there has been increasing attention on thermoelectric materials for their ability to harvest waste heat into useful energy. The efficiency of a thermoelectric material depends on its electrical conductivity, Seebeck coefficient, and thermal conductivity in a conflicting manner which results in efficiency optimization challenges. Single crystals and polycrystalline layered materials have comparatively better thermoelectric and mechanical properties in a certain direction. Texture engineering is a special strategy that allows the exploitation of superior material properties in a specific direction. Texturing could be achieved by various sintering and deformation methods, which yield defects improving thermoelectric and mechanical properties. The results show that for(Bi,Sb)_(2)Te_(3), Bi_(2)(Se,Te)_(3), C uSbSe_(2), and SnSe, significant enhancement in the thermoelectric figure of merit is achieved by enhancing the preferred orientation. Texture engineering provides a wide range of strategies to elevate the zT of anisotropic materials to values comparable to those of their single crystalline counterparts.
基金financially supported by the Joint Funds Project funding from Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B1515120083)the National Natural Science Foundation of China(Grant No.U19A2089)+4 种基金the Key Fundamental Research Project funding from the Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20200109141014474)the National Key Research and Development Project from the Ministry of Science and Technology of China(Grants Nos.2016YFA0202400 and 2016YFA0202404)the Peacock Team Project from Shenzhen Science and Technology Innovation Committee(Grant No.KQTD2015033110182370)Shenzhen Engineering R&D Center for Flexible Solar Cells project funding from Shenzhen Development and Reform Committee(Grant No.2019-126)the Guangdong-Hong Kong-Macao Joint Laboratory(Grant No.2019B121205001).
文摘There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.
基金Large Instrument and Equipment Open Foundation of Dalian University of Technology and Natural Science Foundation。
文摘Aqueous ammonium-ion(NH_(4)^(+))hybrid supercapacitor(AA-HSC),as a new type of energy storage device with great potential,is in the initial stage of rapid development.Based on its special energy storage mechanism,exploiting novel NH_(4)^(+)-hostingmaterials is still a great challenge.Herein,vanadium oxide hydration(VOH)tuned by interlayer engineering of K+/PANI co-intercalation,named KVO/PANI,is designed for AA-HSC.Intercalated PANI can shield interaction between NH_(4)^(+)and V–O layers to some extent and enlarge interlayer space,which improves the efficiency of reversible NH_(4)^(+)(de)insertion.However,K+enhances redox activity and electronic conductivity.The synergistic effect of co-intercalation optimizes intercalation pseudocapacitive behavior during the(de)ammonization process,which is reported in NH_(4)^(+)storage for the first time.Theoretical calculations reveal that the lowered electron transport barrier and enhanced electronic conductivity improveNH_(4)^(+)kinetics and exhibit high capacitance for charge storage.The KVO/PANI can deliver the specific capacitance of 340 F g^(−1) at 0.5 A g^(−1) and retain 177 F g^(−1) at 10 A g^(−1).Pairing with activated carbon,the AA-HSC can achieve a decent energy density of 31.8 Wh kg^(−1).This work gives inorganic/organic co-intercalation that can enhance the NH_(4)^(+)storage of VOH by interlayer engineering.The strategy can be used to design other materials for aqueous energy storage systems.
基金National Safety Academy Foundation(U1830116, U2130112)National Natural Science Foundation of China (62175205)+2 种基金Youth Talent Support Program of Fujian Province (Eyas Plan of Fujian Province)([2022])Shenzhen Science and Technology Innovation Program (JCYJ20220530143015035)Agency for Science,Technology and Research (A20E5c0093, C210112019,C230917001, M21K2c0116, M22K2c0088, NRF2021-QEP2-03-P09)。
文摘2D materials are promising candidates as nonlinear optical components for on-chip devices due to their ultrathin structure. In general, their nonlinear optical responses are inherently weak due to the short interaction thickness with light. Recently, there has been great interest in using quasi-bound states in the continuum (q-BICs) of dielectric metasurfaces, which are able to achieve remarkable optical near-field enhancement for elevating the second harmonic generation (SHG) emission from 2D materials. However, most studies focus on the design of combining bulk dielectric metasurfaces with unpatterned 2D materials, which suffer considerable radiation loss and limit near-field enhancement by high-quality q-BIC resonances. Here, we investigate the dielectric metasurface evolution from bulk silicon to monolayer molybdenum disulfide (MoS2), and discover the critical role of meta-atom thickness design on enhancing near-field effects of two q-BIC modes. We further introduce the strongcoupling of the two q-BIC modes by oblique incidence manipulation, and enhance the localized optical field on monolayer MoS2dramatically. In the ultraviolet and visible regions, the MoS2SHG enhancement factor of our design is 105times higher than that of conventional bulk metasurfaces, leading to an extremely high nonlinear conversion efficiency of 5.8%. Our research will provide an important theoretical guide for the design of high-performance nonlinear devices based on 2D materials.
基金K.S.N.acknowledges support from the Ministry of Education,Singapore(Research Centre of Excellence award to the Institute for Functional Intelligent Materials,I-FIM,project No.EDUNC-33-18-279-V12)and from the Royal Society(UK,grant number RSRP\R\190000).S.M.N.acknowledges the financial support from the Ministry of Science and Higher Education(agreement No.075-15-2022-1150)+2 种基金A.S.S.and A.N.T.gratefully acknowledge the financial support from the RSF(grant No.22-19-00558)D.A.G.,A.V.A.,and V.S.V.acknowledge support from the Higher Education and Science Committee of the Ministry of Education,Science,Culture,and Sport of the Republic of Armenia Project No.23RL-2A031D.M.T.acknowledges support from the M.V.Lomonosov Moscow State University Program of Development.
文摘The emergence of van der Waals(vdW)materials resulted in the discovery of their high optical,mechanical,and electronic anisotropic properties,immediately enabling countless novel phenomena and applications.Such success inspired an intensive search for the highest possible anisotropic properties among vdW materials.Furthermore,the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches.Here,we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization.Using our approach,we found As2S3 as a highly anisotropic vdW material.It demonstrates high in-plane optical anisotropy that is~20%larger than for rutile and over two times as large as calcite,high refractive index,and transparency in the visible range,overcoming the century-long record set by rutile.Given these benefits,As2S3 opens a pathway towards nextgeneration nanophotonics as demonstrated by an ultrathin true zero-order quarter-wave plate that combines classical and the Fabry–Pérot optical phase accumulations.Hence,our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.
基金the Singapore RIE2020 Advanced Manufacturing and Engineering Programmatic grant“Accelerated Materials Development for Manufacturing”by the Agency for Science,Technology and Research under No.A1898b0043.
文摘Rapid and accurate chemical composition identification is critically important in chemistry.While it can be achieved with optical absorption spectrometry by comparing the experimental spectra with the reference data when the chemical compositions are simple,such application is limited in more complicated scenarios especially in nano-scale research.This is due to the difficulties in identifying optical absorption peaks(i.e.,from“featureless”spectra)arose from the complexity.In this work,using the ultraviolet-visible(UV-Vis)absorption spectra of metal nanoclusters(NCs)as a demonstration,we develop a machine-learningbased method to unravel the compositions of metal NCs behind the“featureless”spectra.By implementing a one-dimensional convolutional neural network,good matches between prediction results and experimental results and low mean absolute error values are achieved on these optical absorption spectra that human cannot interpret.This work opens a door for the identification of nanomaterials at molecular precision from their optical properties,paving the way to rapid and high-throughput characterizations.
基金P.C.acknowledges funding from the National Research Foundation under his NRF Fellowship NRFF12-2020-0012.
文摘Understanding the thermodynamic properties of electrolyte solutions is of vital importance for a myriad of physiological and technological applications.The mean activity coefficientγ±is associated with the deviation of an electrolyte solution from its ideal behavior and may be obtained by combining the Debye-Hückel(DH)and Born(B)equations.However,the DH and B equations depend on the concentration and temperature-dependent static permittivity of the solutionεr(c,T)and the size of the solvated ions ri,whose experimental data is often not available.Here,we use a combination of molecular dynamics and density functional theory to predictεr(c,T)and ri,which enables us to apply the DH and B equations to any technologically relevant aqueous and nonaqueous electrolyte at any concentration and temperature of interest.
基金J.Wang acknowledges the support by MOE,Singapore Ministry of Education(MOE2018-T2-2-095)for research work conducted at the National University of Singapore.Z.L.Liu acknowledges the A*STAR’s Central Research Funds(CRF)Award(Project:SC25/21-111312)+1 种基金Y.Gao acknowledges financial support by ST Engineering Advanced Material Engineering Pte.Ltd.and Singapore Economic Development BoardOpen access funding provided by Shanghai Jiao Tong University
文摘Rechargeable batteries of high energy density and overall performance are becoming a critically important technology in the rapidly changing society of the twenty-first century.While lithium-ion batteries have so far been the dominant choice,numerous emerging applications call for higher capacity,better safety and lower costs while maintaining sufficient cyclability.The design space for potentially better alternatives is extremely large,with numerous new chemistries and architectures being simultaneously explored.These include other insertion ions(e.g.sodium and numerous multivalent ions),conversion electrode materials(e.g.silicon,metallic anodes,halides and chalcogens)and aqueous and solid electrolytes.However,each of these potential“beyond lithium-ion”alternatives faces numerous challenges that often lead to very poor cyclability,especially at the commercial cell level,while lithium-ion batteries continue to improve in performance and decrease in cost.This review examines fundamental principles to rationalise these numerous developments,and in each case,a brief overview is given on the advantages,advances,remaining challenges preventing cell-level implementation and the state-of-the-art of the solutions to these challenges.Finally,research and development results obtained in academia are compared to emerging commercial examples,as a commentary on the current and near-future viability of these“beyond lithium-ion”alternatives.
基金This work was supported by the National Natural Science Foundation of China(U1802256,51672128,21773118,21875107,51802154)the Key Research and Development Program in Jiangsu Province(BE2018122)+3 种基金Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).Prof.John Wang and team acknowledge the support by MOE,Singapore Ministry of Education(MOE2018-T2-2-095),for research conducted at the National University of SingaporeMr.Jiangmin Jiang would like to acknowledge the financial support from the Funding of Outstanding Doctoral Dissertation in NUAA(BCXJ19-07)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX19_0174)China Scholarship Council(201906830060).
文摘Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.
基金the National Research Foundation(NRF)Singapore for funding under NRF-CRP17-2017-01(R-284-000-165-281)for the research conducted at the National University of Singapore.
文摘MOFs are among the most popular precursors and templates for deriving various porous materials,where the derivatives can inherit a large surface area,abundant active sites for targeted functionalities and a high degree of porosity inherited from their parent MOFs.Those unique structural features make them promising candidates in multiple applications.More interestingly,the structure and properties of these MOF derivatives can be modulated by the choice of the parent MOFs and the design in the conversion process.In this overview,the transformation pathways from MOFs into their porous derivatives,the principles underlying these transformations,and the behavior of the MOF components in the transition process are discussed.Recently,there has been tremendous progress in preserving and enhancing the surface area,the amount of active sites and the level of porosity of the MOF-derived materials for targeted applications,from the perspectives of both customizing the parent MOFs and tailoring the transformation process.To develop the rationally designed MOF-derived materials and thus to elucidate the precursor-process-product correlations,some typical examples of the MOF derivatives applied in electrochemical energy storage and conversion,water treatment,gas sensing,and biomedicine are discussed to demonstrate the effectiveness of the key design strategies.