Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,an...Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.展开更多
Graphene aerogel(GA),as a novel solid material,has shown great potential in engineering applications due to its unique mechanical properties.In this study,the mechanical performance of GA under high-velocity projectil...Graphene aerogel(GA),as a novel solid material,has shown great potential in engineering applications due to its unique mechanical properties.In this study,the mechanical performance of GA under high-velocity projectile impacts is thoroughly investigated using full-atomic molecular dynamics(MD)simulations.The study results show that the porous structure and density are key factors determining the mechanical response of GA under impact loading.Specifically,the impact-induced penetration of the projectile leads to the collapse of the pore structure,causing stretching and subsequent rupture of covalent bonds in graphene sheets.Moreover,the effects of temperature on the mechanical performance of GA have been proven to be minimal,thereby highlighting the mechanical stability of GA over a wide range of temperatures.Finally,the energy absorption density(EAD)and energy absorption efficiency(EAE)metrics are adopted to assess the energy absorption capacity of GA during projectile penetration.The research findings of this work demonstrate the significant potential of GA for energy absorption applications.展开更多
The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption ...The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER electrocatalysts.In this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis temperature.Optimal experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C electrocatalyst.Benefiting from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.展开更多
Resulting from the development of electric vehicles,high energy-density Li-S batteries have recently attracted ever-increasing attentions worldwide.However,continuous dissolution of cathodic sulfur and followed shuttl...Resulting from the development of electric vehicles,high energy-density Li-S batteries have recently attracted ever-increasing attentions worldwide.However,continuous dissolution of cathodic sulfur and followed shuttle effect of polysulfides lead to very limited service lifetime for currently-applied Li-S batteries.Herein,a 3 D porous graphene aerogel(GA)decorated with high exposure of anatase TiO2(001)nanoplatelets is proposed as robust host to immobilize cathodic sulfur.Compared with commonly used TiO2(101)nanoparticles,the Ti O2(001)nanoplatelets have highly matched lattices with graphene(002)nanosheets,thus facilitating the electronic transfer.The in-site assembled TiO2@GA host exhibits superior sulfur-immobilized capability,which cannot only entrap sulfur by physical confinement,but also capture dissoluble sulfurous species by chemical bonding.The fabricated S@TiO2@GA cathode shows excellent electrochemical performance with high discharge capacity,superior rate capability,and durable cycling stability as well,supposed to be a promising cathode for high-performance Li-S battery applications.展开更多
Anti-CO poisoning ability is significant in formic acid oxidation in the fuel cell technique.Herein,Pd Ni alloy supported on N-doped graphene aerogel(Pd Ni/GA-N)was found to have catalytic ability toward formic acid e...Anti-CO poisoning ability is significant in formic acid oxidation in the fuel cell technique.Herein,Pd Ni alloy supported on N-doped graphene aerogel(Pd Ni/GA-N)was found to have catalytic ability toward formic acid electrooxidation over a wide potential range because of the improved anti-CO poisoning ability.This catalyst was fabricated by simple freeze-drying of mixture solution of graphene aerogel,polyvinylpyrrolidone,Pd^(2+)and Ni^(2+)and the subsequent thermal annealing reduction approach in the N2/H2 atmosphere.Pd-Ni alloy particles anchored over the folding N-doped graphene surface with a porous hierarchical architecture structure in the 3 D directions.It showed the catalytic performance of its maximum mass activity of 836 m A mg^(-1)in a broad potential range(0.2-0.6 V)for formic acid oxidation.The CO stripping experiment demonstrated its largely improved anti-CO poisoning ability with the peak potential of 0.67 V,approximately 60 and 40 m V less compared to those of Pd/GA-N and Pd/C samples.The high anti-CO poisoning ability and strong electronic effect resulting from the interaction between the3 D GA-N support and the Pd-Ni alloy makes it a promising catalyst for application in direct formic acid fuel cells.展开更多
Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance s...Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance supercapacitors. The as-obtained material possesses a hierarchically porous structure and a large number of electrochemical active sites. At a current density of 1 Ag^-1, the specific capacitance of the N/S-GA-2 for supercapacitors with the ionic liquid as the electrolyte is 169.4 Fg^-1, and the corresponding energy density is 84.5 Wh kg^-1.At a power density of 8.9 k W kg^-1, the energy density can reach up to 75.7 Wh kg^-1, showing that the N/S-GA-2 has an excellent electrochemical performance. Consequently, the N/S-GA-2 can be used as a promising candidate of electrode materials for supercapacitors with high power density and high energy density.展开更多
Graphene aerogel was synthesized and used for the removal of methyl blue from aqueous solutions.The effect of solution pH,temperature and adsorption time on the adsorption performance of the graphene aerogel was studi...Graphene aerogel was synthesized and used for the removal of methyl blue from aqueous solutions.The effect of solution pH,temperature and adsorption time on the adsorption performance of the graphene aerogel was studied systematically.In addition,investigations were also performed to determine the nature of adsorption.The experimental results show that graphene aerogel is a highly efficient adsorbent for the treatment of methyl blue in aqueous solutions.In addition,the adsorption of methyl blue proceeds through a single layer physical adsorption on the graphene aerogel.The findings herein are useful for the future development of adsorbent for in water.展开更多
Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle eff...Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.展开更多
Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor...Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor mechanical properties and low recycling efficiency.Here,superelastic graphene aerogel(SGA)was prepared through one-step freezing and twice hydrothermal reduction followed by drying under ambient pressure.The simple atmospheric drying provides a possibility for large-scale preparation of high performance graphene-based aerogels.The prepared SGA not only has the ability of highly repeatable compression rebound,but also exhibits excellent oil adsorption performance.And the overall performance of SGA is better than most of graphenebased aerogels prepared by freeze drying.After the SGA was cyclically compressed with 70%strain for 300 times,it can return to the original shape and height substantially.SGA retained about 90%of the initial adsorption capacity after 50 cycles of adsorption and compression regeneration for cyclohexane.展开更多
With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite h...With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.展开更多
Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide(MoS2) is very promising for applicat...Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide(MoS2) is very promising for applications in hydrogen production and pollutant photodegradation.However,its lack of active sites and the difficulty of recovering catalysts in powder form have hindered its wide application.Here,we report the successful preparation of a macroscopic visible-light responsive MoS2/reduced graphene oxide(MoS2/RGO) aerogel.The obtained MoS2/RGO aerogel exhibits enhanced photocatalytic activity towards hydrogen production and photoreduction of Cr(Ⅵ) in comparison with the MoS2 powder.In addition,the low density(56.1 mg/cm^3) of the MoS2/RGO aerogel enables it to be used as an efficient adsorption material for organic pollutants.Our results demonstrate that this very promising multifunctional aerogel has potential applications in environmental remediation and clean energy production.展开更多
Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-spe...Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.展开更多
Graphene-aerogel-based flexible sensors have heat tolerances and electric-resistance sensitivities superior to those of polymer-based sensors.However,graphene sheets are prone to slips under repeated compression due t...Graphene-aerogel-based flexible sensors have heat tolerances and electric-resistance sensitivities superior to those of polymer-based sensors.However,graphene sheets are prone to slips under repeated compression due to inadequate chemical con-nections.In addition,the heat-transfer performance of existing compression strain sensors under stress is unclear and lacks research,making it difficult to perform real-temperature detections.To address these issues,a hyperelastic polyimide fiber/graphene aerogel(PINF/GA)with a three-dimensional interconnected structure was fabricated by simple one-pot compound-ing and in-situ welding methods.The welding of fiber lap joints promotes in-suit formation of three-dimensional crosslinked networks of polyimide fibers,which can effectively avoid slidings between fibers to form reinforced ribs,preventing graphene from damage during compression.In particular,the inner core of the fiber maintains its macromolecular chain structure and toughness during welding.Thus,PINF/GA has good structural stabilities under a large strain compression(99%).Moreover,the thermal and electrical conductivities of PINF/GA could not only change with various stresses and strains but also keep the change steady at specific stresses and strains,with its thermal-conductivity change ratio reaching up to 9.8.Hyperelastic PINF/GA,with dynamically stable thermal and electrical conductivity,as well as high heat tolerance,shows broad applica-tion prospects as sensors in detecting the shapes and temperatures of unknown objects in extreme environments.展开更多
Alcohol fuels oxidation plays a significant role in carbon sustainable cycling and high-performance cata-lyst with a strong anti-poisoning effect is desired.Herein,Pt-Ni alloy supported on the N-doped graphene aerogel...Alcohol fuels oxidation plays a significant role in carbon sustainable cycling and high-performance cata-lyst with a strong anti-poisoning effect is desired.Herein,Pt-Ni alloy supported on the N-doped graphene aerogel synthesized by simple freeze-drying and annealing was demonstrated to have such catalytic abil-ity for alcohol fuel oxidation.Pt-Ni alloy particles were found uniformly dispersed over the surface of 3D N-doped graphene aerogel.High anti-poisoning ability for CO-like intermediates oxidation was demon-strated by the CO-stripping experiment.The as-prepared catalyst was found to have outstanding catalytic performance for methanol and ethanol oxidation with high catalytic activity,stability and catalytic ki-netics.Compared to the control samples,the improved catalytic ability could be due to the presence of oxophilic Ni species and the support effect of 3D N-doped graphene aerogel that combined multi-advantages of large surface area,facile mass transfer,and abundant defects.展开更多
A novel metal-free bulk nanocatalyst, S--N-codoped hollow carbon nanosphere/ graphene aerogel (SNC-GA-1000), has been successfully fabricated using a facile and clean solid ion transition route. In this method, ZnS ...A novel metal-free bulk nanocatalyst, S--N-codoped hollow carbon nanosphere/ graphene aerogel (SNC-GA-1000), has been successfully fabricated using a facile and clean solid ion transition route. In this method, ZnS is used as the hard template and S source, while polydopamine acts as a reducing agent and carbon source. At a high annealing temperature, Zn metal is reduced and evaporates, leaving only free S vapor to diffuse into the carbon layer. Interestingly, the as-obtained SNC-GA-1000 exhibits much higher catalytic activity in an organic reduction reaction than unloaded bare S--N-codoped carbon nanospheres. Hydrothermal reduction of the graphene oxide sheets loaded with ZnSC@olydopamine core-shell nanospheres (ZnS@PDA) affords a three-dimensional bulk graphene aerogel. Although nanosized catalysts exhibit high catalytic activities, their subsequent separation is not always satisfactory, making post-treatment difficult. This approach achieves a trade-off between activity and separability. More importantly, due to the 3D structural nature, such bulk and handheld nanocatalysts can be easily separated and recycled.展开更多
To enhance the mechanical properties of three-dimensional graphene aerogels with aramid fibers, graphene/organic fiber aerogels are prepared by chemical reduction of graphene oxide in the presence of organic fibers of...To enhance the mechanical properties of three-dimensional graphene aerogels with aramid fibers, graphene/organic fiber aerogels are prepared by chemical reduction of graphene oxide in the presence of organic fibers of poly(p-phenylene terephthalamide) (PPTA) and followed by freeze-drying. Thermal annealing of the composite aerogels at 1300℃ is adopted not only to restore the conductivity of the reduced graphene oxide component but also to convert the insulating PPTA organic fibers to conductive carbon fibers by the carbonization. The resultant graphene/carbon fiber aerogels (GCFAs) exhibit high electrical conductivities and enhanced compressive properties, which are highly efficient in improving both mechanical and electrical performances of epoxy composites. Compared to those of neat epoxy, the compressive modulus, compressive strength and energy absorption of the electrically conductive GCFA/epoxy composite are significantly increased by 60%, 59% and 131%, respectively.展开更多
In the pursuit of heterogeneous catalysts with high reactivity,metal organic framework(MOF)nanomaterials have received tremendous attentions.However,many MOF catalysts especially Fe-based MOFs need to be utilized imme...In the pursuit of heterogeneous catalysts with high reactivity,metal organic framework(MOF)nanomaterials have received tremendous attentions.However,many MOF catalysts especially Fe-based MOFs need to be utilized immediately after synthesis or being activated using high temperature,because of the easy loss of reactivity in humid environments resulting from the occupation of active Fe sites by water molecules.Here,we describe an inspiring strategy of growing MIL-101-Fe nanoparticles inside the three-dimensional confined space of graphene aerogel(GA),generating shapeable GA/MIL-101-Fe nanocomposite convenient for practical use.Compared to MIL-101-Fe,GA/MIL-101-Fe as catalyst demonstrates much higher reactivity in Fenton-like reaction,attributing to smaller MIL-101-Fe particle size,presence of active Fe(II)sites,and abundant defects in GA.Strikingly,the weakly hydrophobic nature of the composite greatly inhibits the loss of catalytic reactivity after being stored in humid air and accelerates the recovery of reactivity in mild temperature,by resisting the entrance of water molecules and helping to exclude water molecules.This work demonstrates that a delicate design of nanocomposite structure could not only improve the reactivity of the catalytic component,but also overcome its intrinsic drawback by taking advantage of the properties of host.We hope this functional nanoconfinement strategy could be extended to more scenarios in other fields.展开更多
The development of deeply cyclable lithium metal batteries with fast-charging capability offers a promising solution to relieve the“range anxiety”in driving electric vehicles.Conventional lithium metal anodes suffer...The development of deeply cyclable lithium metal batteries with fast-charging capability offers a promising solution to relieve the“range anxiety”in driving electric vehicles.Conventional lithium metal anodes suffered from low operating current densities and shallow charge/discharge depths,owing to the intrinsic dendrite growth governed by Sand’s law.Herein,we come up with a novel design of heavy-duty lithium metal anode fabricated by partially infusing the three-dimensional(3D)porous graphene aerogel with molten Li.Both electroanalytical measurements and simulations show that the unique electrode architecture brings notable advantages in mediating smooth Li plating/stripping,including reduced local current density,inhibited dendrite growth,buffered volume fluctuation,as well as more efficient Li utilization.Consequently,a remarkable cycling performance in symmetric cells for over 400 cycles(800 h)with an ultrahigh cycling capacity of 15 mAh·cm^(−2) at 15 mA·cm^(−2) is achieved,which,to our best knowledge,has been never seen in literature.LiFePO4 full cells demonstrate a superb rate capability up to 10 C and a prolonged cycling of 1,600 cycles at 2 C with the per-cycle capacity decay of only 0.023%.This study paves the way for the ultimate deployment of lithium metal batteries in real-world applications that require fast charging and deep cycling.展开更多
Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electric...Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide (GO) self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide (rGO) aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus (E) scaled with density (p) as E-p^2. The rGO aerogels also exhibited high conductivities (e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3) and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.展开更多
Three-dimensional(3 D)graphene-based aerogels have significant potential for adsorption,sensors,and thermal management applications.However,their practical applications are limited by their disorganized structure and ...Three-dimensional(3 D)graphene-based aerogels have significant potential for adsorption,sensors,and thermal management applications.However,their practical applications are limited by their disorganized structure and ultra-low resilience after compression.Some methods can realize a well-aligned structure,however,they involve high costs and complex technology.Herein,a 3 D graphene hybrid aerogel with an anisotropic open-cell and well-oriented structure is realized by unidirectional freeze casting,which combines the‘soft’(e.g.graphene oxide,Tween-80)and‘hard’(e.g.graphene assembly)components to realize full recovery after flattening.A graphene aerogel annealed at a moderate temperature(200℃)can possess superhydrophilicity and outstanding wet-resilience properties,including after being pressed under40 MPa.Furthermore,the graphene aerogel annealed at a high temperature of 1500℃exhibits excellent thermal conductivity enhancement efficiency in polydimethylsiloxane(PDMS).The resultant nanocomposites clearly demonstrate anisotropic thermal conductivity and promising applications as thermal interface materials.This strategy offers new insights into the design and fabrication of 3 D multifunctional graphene aerogels.展开更多
基金The financial support by the National Natural Science Foundation of China(No.52002020)is acknowledged.
文摘Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.
基金supported by the National Natural Science Foundation of China(No.12102256).
文摘Graphene aerogel(GA),as a novel solid material,has shown great potential in engineering applications due to its unique mechanical properties.In this study,the mechanical performance of GA under high-velocity projectile impacts is thoroughly investigated using full-atomic molecular dynamics(MD)simulations.The study results show that the porous structure and density are key factors determining the mechanical response of GA under impact loading.Specifically,the impact-induced penetration of the projectile leads to the collapse of the pore structure,causing stretching and subsequent rupture of covalent bonds in graphene sheets.Moreover,the effects of temperature on the mechanical performance of GA have been proven to be minimal,thereby highlighting the mechanical stability of GA over a wide range of temperatures.Finally,the energy absorption density(EAD)and energy absorption efficiency(EAE)metrics are adopted to assess the energy absorption capacity of GA during projectile penetration.The research findings of this work demonstrate the significant potential of GA for energy absorption applications.
文摘The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER electrocatalysts.In this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis temperature.Optimal experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C electrocatalyst.Benefiting from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.
基金financially supported by the National Key R and D Program of China(No.2019YFA0210300)the Hunan Provincial Natural Science Foundation of China(No.2019JJ40359)+1 种基金the Hunan Provincial S and T Plan of China(Nos.2017TP1001,2016TP1007)the Open-End Fund for the Valuable and Precision Instruments of Central South University(CSUZC2020016)。
文摘Resulting from the development of electric vehicles,high energy-density Li-S batteries have recently attracted ever-increasing attentions worldwide.However,continuous dissolution of cathodic sulfur and followed shuttle effect of polysulfides lead to very limited service lifetime for currently-applied Li-S batteries.Herein,a 3 D porous graphene aerogel(GA)decorated with high exposure of anatase TiO2(001)nanoplatelets is proposed as robust host to immobilize cathodic sulfur.Compared with commonly used TiO2(101)nanoparticles,the Ti O2(001)nanoplatelets have highly matched lattices with graphene(002)nanosheets,thus facilitating the electronic transfer.The in-site assembled TiO2@GA host exhibits superior sulfur-immobilized capability,which cannot only entrap sulfur by physical confinement,but also capture dissoluble sulfurous species by chemical bonding.The fabricated S@TiO2@GA cathode shows excellent electrochemical performance with high discharge capacity,superior rate capability,and durable cycling stability as well,supposed to be a promising cathode for high-performance Li-S battery applications.
基金supported by the National Natural Science Foundation of China(21972124,21603041)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institution+1 种基金the Double Tops Joint Fund of the Yunnan Science and Technology Bureau and Yunnan University(2019FY003025)the Research Foundation of Department of Education of Yunnan Province(2020Y0018)。
文摘Anti-CO poisoning ability is significant in formic acid oxidation in the fuel cell technique.Herein,Pd Ni alloy supported on N-doped graphene aerogel(Pd Ni/GA-N)was found to have catalytic ability toward formic acid electrooxidation over a wide potential range because of the improved anti-CO poisoning ability.This catalyst was fabricated by simple freeze-drying of mixture solution of graphene aerogel,polyvinylpyrrolidone,Pd^(2+)and Ni^(2+)and the subsequent thermal annealing reduction approach in the N2/H2 atmosphere.Pd-Ni alloy particles anchored over the folding N-doped graphene surface with a porous hierarchical architecture structure in the 3 D directions.It showed the catalytic performance of its maximum mass activity of 836 m A mg^(-1)in a broad potential range(0.2-0.6 V)for formic acid oxidation.The CO stripping experiment demonstrated its largely improved anti-CO poisoning ability with the peak potential of 0.67 V,approximately 60 and 40 m V less compared to those of Pd/GA-N and Pd/C samples.The high anti-CO poisoning ability and strong electronic effect resulting from the interaction between the3 D GA-N support and the Pd-Ni alloy makes it a promising catalyst for application in direct formic acid fuel cells.
基金Financial support from the National Natural Science Foundation of China (Nos. 21873026 and 21573058)the Program for Innovative Research Team in Science and Technology in University of Henan Province (17IRTSTHN 001) is gratefully acknowledged
文摘Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance supercapacitors. The as-obtained material possesses a hierarchically porous structure and a large number of electrochemical active sites. At a current density of 1 Ag^-1, the specific capacitance of the N/S-GA-2 for supercapacitors with the ionic liquid as the electrolyte is 169.4 Fg^-1, and the corresponding energy density is 84.5 Wh kg^-1.At a power density of 8.9 k W kg^-1, the energy density can reach up to 75.7 Wh kg^-1, showing that the N/S-GA-2 has an excellent electrochemical performance. Consequently, the N/S-GA-2 can be used as a promising candidate of electrode materials for supercapacitors with high power density and high energy density.
基金Funded by the Natural Science Foundation of Hubei Province(2018CFB785)。
文摘Graphene aerogel was synthesized and used for the removal of methyl blue from aqueous solutions.The effect of solution pH,temperature and adsorption time on the adsorption performance of the graphene aerogel was studied systematically.In addition,investigations were also performed to determine the nature of adsorption.The experimental results show that graphene aerogel is a highly efficient adsorbent for the treatment of methyl blue in aqueous solutions.In addition,the adsorption of methyl blue proceeds through a single layer physical adsorption on the graphene aerogel.The findings herein are useful for the future development of adsorbent for in water.
基金supported by the National Natural Science Foundation of China(51974209)the Outstanding Doctoral Award Fund in Shanxi Province(20202017)。
文摘Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.
基金the financial support of National Natural Science Foundation of China (22078366)
文摘Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor mechanical properties and low recycling efficiency.Here,superelastic graphene aerogel(SGA)was prepared through one-step freezing and twice hydrothermal reduction followed by drying under ambient pressure.The simple atmospheric drying provides a possibility for large-scale preparation of high performance graphene-based aerogels.The prepared SGA not only has the ability of highly repeatable compression rebound,but also exhibits excellent oil adsorption performance.And the overall performance of SGA is better than most of graphenebased aerogels prepared by freeze drying.After the SGA was cyclically compressed with 70%strain for 300 times,it can return to the original shape and height substantially.SGA retained about 90%of the initial adsorption capacity after 50 cycles of adsorption and compression regeneration for cyclohexane.
基金sponsored by National Natural Science Foundation of China(No.52302121,No.52203386)Shanghai Sailing Program(No.23YF1454700)+1 种基金Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664).
文摘With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.
基金supported by the National Natural Science Foundation of China (U1232119, 21403172)the Sichuan Youth Science and Technology Foundation (2013JQ0034, 2014JQ0017)the Innovative Research Team of Sichuan Province (2016TD0011)~~
文摘Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide(MoS2) is very promising for applications in hydrogen production and pollutant photodegradation.However,its lack of active sites and the difficulty of recovering catalysts in powder form have hindered its wide application.Here,we report the successful preparation of a macroscopic visible-light responsive MoS2/reduced graphene oxide(MoS2/RGO) aerogel.The obtained MoS2/RGO aerogel exhibits enhanced photocatalytic activity towards hydrogen production and photoreduction of Cr(Ⅵ) in comparison with the MoS2 powder.In addition,the low density(56.1 mg/cm^3) of the MoS2/RGO aerogel enables it to be used as an efficient adsorption material for organic pollutants.Our results demonstrate that this very promising multifunctional aerogel has potential applications in environmental remediation and clean energy production.
基金This work was financially supported by the National Natural Science Foundation of China(No.51903213)the Science and Technology Planning Project of Sichuan Province(Nos.2018GZ0132 and 2018GZ0427).
文摘Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.
基金supported by National Key R&D Program of China(No.2022YFB3805702)National Natural Science Foundation of China(Grant Nos.52173078,52130303,51973158,51803151,and 51973152)the Science Foundation for Distinguished Young Scholars in Tianjin(No.19JCJQJC61700).
文摘Graphene-aerogel-based flexible sensors have heat tolerances and electric-resistance sensitivities superior to those of polymer-based sensors.However,graphene sheets are prone to slips under repeated compression due to inadequate chemical con-nections.In addition,the heat-transfer performance of existing compression strain sensors under stress is unclear and lacks research,making it difficult to perform real-temperature detections.To address these issues,a hyperelastic polyimide fiber/graphene aerogel(PINF/GA)with a three-dimensional interconnected structure was fabricated by simple one-pot compound-ing and in-situ welding methods.The welding of fiber lap joints promotes in-suit formation of three-dimensional crosslinked networks of polyimide fibers,which can effectively avoid slidings between fibers to form reinforced ribs,preventing graphene from damage during compression.In particular,the inner core of the fiber maintains its macromolecular chain structure and toughness during welding.Thus,PINF/GA has good structural stabilities under a large strain compression(99%).Moreover,the thermal and electrical conductivities of PINF/GA could not only change with various stresses and strains but also keep the change steady at specific stresses and strains,with its thermal-conductivity change ratio reaching up to 9.8.Hyperelastic PINF/GA,with dynamically stable thermal and electrical conductivity,as well as high heat tolerance,shows broad applica-tion prospects as sensors in detecting the shapes and temperatures of unknown objects in extreme environments.
基金supported by the Hunan Provincial Natural Sci-ence Foundation of China(No.2019JJ50411)the Scientific Re-search Fund of Hunan University of Arts and Science(No.20ZD02)The work was also supported by the National Natural Science Foundation of China(Nos.21972124,21603041).
文摘Alcohol fuels oxidation plays a significant role in carbon sustainable cycling and high-performance cata-lyst with a strong anti-poisoning effect is desired.Herein,Pt-Ni alloy supported on the N-doped graphene aerogel synthesized by simple freeze-drying and annealing was demonstrated to have such catalytic abil-ity for alcohol fuel oxidation.Pt-Ni alloy particles were found uniformly dispersed over the surface of 3D N-doped graphene aerogel.High anti-poisoning ability for CO-like intermediates oxidation was demon-strated by the CO-stripping experiment.The as-prepared catalyst was found to have outstanding catalytic performance for methanol and ethanol oxidation with high catalytic activity,stability and catalytic ki-netics.Compared to the control samples,the improved catalytic ability could be due to the presence of oxophilic Ni species and the support effect of 3D N-doped graphene aerogel that combined multi-advantages of large surface area,facile mass transfer,and abundant defects.
基金Acknowledgements The authors are grateful for the financial aid from the National Natural Science Foundation of China (Nos. 51372242, 21590794, 21210001, and 21521092), Hong Kong, Macao and Taiwan Science and Technology Cooperation Special Project of Ministry of Science and Technology of China (No. 2014DFT10310), the National Key Basic Research Program of China (No. 2014CB643802), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2011176), CAS- CSIRO project (No. GJHZ1730) and the Program of Science and Technology Development Plan of Jilin Province of China (No. 20140201007GX).
文摘A novel metal-free bulk nanocatalyst, S--N-codoped hollow carbon nanosphere/ graphene aerogel (SNC-GA-1000), has been successfully fabricated using a facile and clean solid ion transition route. In this method, ZnS is used as the hard template and S source, while polydopamine acts as a reducing agent and carbon source. At a high annealing temperature, Zn metal is reduced and evaporates, leaving only free S vapor to diffuse into the carbon layer. Interestingly, the as-obtained SNC-GA-1000 exhibits much higher catalytic activity in an organic reduction reaction than unloaded bare S--N-codoped carbon nanospheres. Hydrothermal reduction of the graphene oxide sheets loaded with ZnSC@olydopamine core-shell nanospheres (ZnS@PDA) affords a three-dimensional bulk graphene aerogel. Although nanosized catalysts exhibit high catalytic activities, their subsequent separation is not always satisfactory, making post-treatment difficult. This approach achieves a trade-off between activity and separability. More importantly, due to the 3D structural nature, such bulk and handheld nanocatalysts can be easily separated and recycled.
基金financially supported by the National Key Research and Development Program of China(No.2016YFC0801302)the National Natural Science Foundation of China(Nos.51403016,51533001 and 51521062)
文摘To enhance the mechanical properties of three-dimensional graphene aerogels with aramid fibers, graphene/organic fiber aerogels are prepared by chemical reduction of graphene oxide in the presence of organic fibers of poly(p-phenylene terephthalamide) (PPTA) and followed by freeze-drying. Thermal annealing of the composite aerogels at 1300℃ is adopted not only to restore the conductivity of the reduced graphene oxide component but also to convert the insulating PPTA organic fibers to conductive carbon fibers by the carbonization. The resultant graphene/carbon fiber aerogels (GCFAs) exhibit high electrical conductivities and enhanced compressive properties, which are highly efficient in improving both mechanical and electrical performances of epoxy composites. Compared to those of neat epoxy, the compressive modulus, compressive strength and energy absorption of the electrically conductive GCFA/epoxy composite are significantly increased by 60%, 59% and 131%, respectively.
基金The authors thanked the financial support from the National Natural Science Foundation of China(No.21925602)Natural Science Foundation of Jiangsu Province(No.BK20201309)the Fundamental Research Funds for the Central Universities(No.30920021116).
文摘In the pursuit of heterogeneous catalysts with high reactivity,metal organic framework(MOF)nanomaterials have received tremendous attentions.However,many MOF catalysts especially Fe-based MOFs need to be utilized immediately after synthesis or being activated using high temperature,because of the easy loss of reactivity in humid environments resulting from the occupation of active Fe sites by water molecules.Here,we describe an inspiring strategy of growing MIL-101-Fe nanoparticles inside the three-dimensional confined space of graphene aerogel(GA),generating shapeable GA/MIL-101-Fe nanocomposite convenient for practical use.Compared to MIL-101-Fe,GA/MIL-101-Fe as catalyst demonstrates much higher reactivity in Fenton-like reaction,attributing to smaller MIL-101-Fe particle size,presence of active Fe(II)sites,and abundant defects in GA.Strikingly,the weakly hydrophobic nature of the composite greatly inhibits the loss of catalytic reactivity after being stored in humid air and accelerates the recovery of reactivity in mild temperature,by resisting the entrance of water molecules and helping to exclude water molecules.This work demonstrates that a delicate design of nanocomposite structure could not only improve the reactivity of the catalytic component,but also overcome its intrinsic drawback by taking advantage of the properties of host.We hope this functional nanoconfinement strategy could be extended to more scenarios in other fields.
基金financially supported by the National Natural Science Foundation of China(Nos.22075193 and 22072101)the Natural Science Foundation of Jiangsu Province(No.BK20211306)+2 种基金the Key Technology Initiative of Suzhou Municipal Science and Technology Bureau(No.SYG201934)Six Talent Peaks Project in Jiangsu Province(No.TD-XCL-006)the support from the Honorary Professor Program of Jiangsu Province and Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘The development of deeply cyclable lithium metal batteries with fast-charging capability offers a promising solution to relieve the“range anxiety”in driving electric vehicles.Conventional lithium metal anodes suffered from low operating current densities and shallow charge/discharge depths,owing to the intrinsic dendrite growth governed by Sand’s law.Herein,we come up with a novel design of heavy-duty lithium metal anode fabricated by partially infusing the three-dimensional(3D)porous graphene aerogel with molten Li.Both electroanalytical measurements and simulations show that the unique electrode architecture brings notable advantages in mediating smooth Li plating/stripping,including reduced local current density,inhibited dendrite growth,buffered volume fluctuation,as well as more efficient Li utilization.Consequently,a remarkable cycling performance in symmetric cells for over 400 cycles(800 h)with an ultrahigh cycling capacity of 15 mAh·cm^(−2) at 15 mA·cm^(−2) is achieved,which,to our best knowledge,has been never seen in literature.LiFePO4 full cells demonstrate a superb rate capability up to 10 C and a prolonged cycling of 1,600 cycles at 2 C with the per-cycle capacity decay of only 0.023%.This study paves the way for the ultimate deployment of lithium metal batteries in real-world applications that require fast charging and deep cycling.
基金This work was supported Foundation for Returned Education of China, Key by the Scientific Research Scholars, the Ministry of Basic Research Projects of Science and Technology Commission of Shanghai (No.11JC1412900), and the National Science Foundation of China program (Nos. 21271140, 51472182).
文摘Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide (GO) self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide (rGO) aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus (E) scaled with density (p) as E-p^2. The rGO aerogels also exhibited high conductivities (e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3) and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.
基金financially supported by the National Natural Science Foundation of China(No.U19A20105)。
文摘Three-dimensional(3 D)graphene-based aerogels have significant potential for adsorption,sensors,and thermal management applications.However,their practical applications are limited by their disorganized structure and ultra-low resilience after compression.Some methods can realize a well-aligned structure,however,they involve high costs and complex technology.Herein,a 3 D graphene hybrid aerogel with an anisotropic open-cell and well-oriented structure is realized by unidirectional freeze casting,which combines the‘soft’(e.g.graphene oxide,Tween-80)and‘hard’(e.g.graphene assembly)components to realize full recovery after flattening.A graphene aerogel annealed at a moderate temperature(200℃)can possess superhydrophilicity and outstanding wet-resilience properties,including after being pressed under40 MPa.Furthermore,the graphene aerogel annealed at a high temperature of 1500℃exhibits excellent thermal conductivity enhancement efficiency in polydimethylsiloxane(PDMS).The resultant nanocomposites clearly demonstrate anisotropic thermal conductivity and promising applications as thermal interface materials.This strategy offers new insights into the design and fabrication of 3 D multifunctional graphene aerogels.