Covalent organic frameworks(COFs)have great potential as adsorbents due to their customizable functionality,low density and high porosity.However,COFs powder exists with poor processing and recycling performance.Moreo...Covalent organic frameworks(COFs)have great potential as adsorbents due to their customizable functionality,low density and high porosity.However,COFs powder exists with poor processing and recycling performance.Moreover,due to the accumulation of COFs nanoparticles,it is not conducive to the full utilization of their surface functional groups.Currently,the strategy of COFs assembling into aerogel can be a good solution to this problem.Herein,we successfully synthesize composite aerogels(CSR)by in-situ self-assembly of two-dimensional COFs and graphene based on crosslinking of sodium alginate.Sodium alginate in the composite improves the mechanical properties of the aerogel,and graphene provides a template for the in-situ growth of COFs.Impressively,CSR aerogels with different COFs and sizes can be prepared by changing the moiety of the ligand and modulating the addition amount of COFs.The prepared CSR aerogels exhibit porous,low density,good processability and good mechanical properties.Among them,the density of CSR-N-1.6 is only 5 mg/cm3,which is the lowest density among the reported COF aerogels so far.Due to these remarkable properties,CSR aerogels perform excellent adsorption and recycling properties for the efficient and rapid removal of organic pollutants(organic dyes and antibiotics)from polluted water.In addition,it is also possible to visually recognize the presence of antibiotics by fluorescence detection.This work not only provides a new strategy for synthesizing COF aerogels,but also accelerates the practical application of COF aerogels and contributes to environmental remediation.展开更多
Although multifunctional electromagnetic interference(EMI)shielding materials with ultrahigh electromagnetic wave absorption are highly required to solve increasingly serious electromagnetic radiation and pollution an...Although multifunctional electromagnetic interference(EMI)shielding materials with ultrahigh electromagnetic wave absorption are highly required to solve increasingly serious electromagnetic radiation and pollution and meet multi-scenario applications,EMI shielding materials usually cause a lot of reflection and have a single function.To realize the broadband absorption-dominated EMI shielding via absorption-reflection-reabsorption mechanisms and the interference cancelation effect,multifunctional asymmetric bilayer aerogels are designed by sequential printing of a MXene-graphene oxide(MG)layer with a MG emulsion ink and a conductive MXene layer with a MXene ink and subsequent freeze-drying for generating and solidifying numerous pores in the aerogels.The top MG layer of the asymmetric bilayer aerogel optimizes impedance matching and achieves re-absorption,while the bottom MXene layer enhances the reflection of the incident electromagnetic waves.As a result,the asymmetric bilayer aerogel achieves an average absorption coefficient of 0.95 in the X-band and shows the tunable absorption ability to electromagnetic wave in the ultrawide band from 8.2 to 40 GHz.Finite element simulations substantiate the effectiveness of the asymmetric bilayer aerogel for electromagnetic wave absorption.The multifunctional bilayer aerogels exhibit hydrophobicity,thermal insulation and Joule heating capacities and are efficient in solar-thermal/electric heating,infrared stealth,and clean-up of spilled oil.展开更多
Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density...Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.展开更多
Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate...Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.展开更多
Ceramic aerogels(CAs)have emerged as a significant research frontier across various applications due to their lightweight,high porosity,and easily tunable structural characteristics.However,the intrinsic weak interact...Ceramic aerogels(CAs)have emerged as a significant research frontier across various applications due to their lightweight,high porosity,and easily tunable structural characteristics.However,the intrinsic weak interactions among the constituent nanoparticles,coupled with the limited toughness of traditional CAs,make them susceptible to structural collapse or even catastrophic failure when exposed to complex mechanical external forces.Unlike 0D building units,1D ceramic nanofibers(CNFs)possess a high aspect ratio and exceptional flexibility simultaneously,which are desirable building blocks for elastic CAs.This review presents the recent progress in electrospun ceramic nanofibrous aerogels(ECNFAs)that are constructed using ECNFs as building blocks,focusing on the various preparation methods and corresponding structural characteristics,strategies for optimizing mechanical performance,and a wide range of applications.The methods for preparing ECNFs and ECNFAs with diverse structures were initially explored,followed by the implementation of optimization strategies for enhancing ECNFAs,emphasizing the improvement of reinforcing the ECNFs,establishing the bonding effects between ECNFs,and designing the aggregate structures of the aerogels.Moreover,the applications of ECNFAs across various fields are also discussed.Finally,it highlights the existing challenges and potential opportunities for ECNFAs to achieve superior properties and realize promising prospects.展开更多
As the application scenarios of aerogels expand,higher requirements are put forward for the materials used to prepare aerogels.Due to the unique chemical structure,polytetrafluoroethylene(PTFE)has excellent properties...As the application scenarios of aerogels expand,higher requirements are put forward for the materials used to prepare aerogels.Due to the unique chemical structure,polytetrafluoroethylene(PTFE)has excellent properties such as high-temperature resistance,hydrophobicity,and chemical stability.However,the PTFE aerogels are difficult to be molded due to the weak interaction between resin particles.In this work,poly(ethylene oxide)(PEO)was selected as the carrier to assist the PTFE aerogels molding.The pure PTFE aerogels were prepared by homogeneously mixing PTFE aqueous dispersion and PEO,freeze-drying,and high-temperature sintering.When the mass fraction of PTFE and PEO were appropriate,the porosity of PTFE aerogels exceeded 90%and had a hierarchical honeycomb structure.Results showed that the PTFE aerogels not only had excellent hydrophobicity but also possessed superior acoustic insulation,mechanical strength,thermal insulation,and heat resistance properties.Specifically,the water contact angle is about 140°.The noise reduction coefficient is 0.34 and the average sound absorption coefficient is greater than 88%in the frequency range of 2000-6400 Hz.Meanwhile,the thermal conductivity in the air is about 0.045 W/(m·K),and the initial thermal decomposition temperature is 450℃.More importantly,the PTFE aerogels had excellent temperature and corrosion resistance.Even after extremely thermal and chemical treatment,they remained unchanged porous structure as well as acoustic and thermal insulation properties,which exhibits great potential for application in many harsh environments.展开更多
Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages,such as fine building block size together with high specific surface area,abundant pore...Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages,such as fine building block size together with high specific surface area,abundant pore structure,etc.Additionally,monolithic aerogels possess a unique monolithic macrostructure that sets them apart from aerogel powders and nanoparticles in practical environmental clean-up applications.This review delves into the available synthesis strategies and atmospheric environmental applications of monolithic aerogels,covering types of monolithic aerogels including SiO_(2),graphene,metal oxides and their combinations,along with their preparation methods.In particular,recent developments for VOC adsorption,CO_(2)capture,catalytic oxidation of VOCs and catalytic reduction of CO_(2)are highlighted.Finally,challenges and future opportunities for monolithic aerogels in the atmospheric environmental purification field are proposed.This reviewprovides valuable insights for designing and utilizing monolithic aerogel-based functional materials.展开更多
Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica a...Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica aerogels decreased greatly caused by transparency to heat radiation.Opacifiers introduced into silica sol can block heat radiation yet destroy the uniformity of aerogels.Herein,we designed and prepared a silica aerogel composite with oriented and layered silica fibers(SFs),SiC nanowires(SiC_(NWs)),and silica aerogels,which were prepared by papermaking,chemical vapor infiltration(CVI),and sol-gel respectively.Firstly,oriented and layered SFs made still air a wall to block heat transfer by the solid phase.Secondly,SiC_(NWs) were grown in situ on the surface of SFs evenly to weave into the network,and the network reduced the gaseous thermal conductivity by dividing cracks in SFs/SiC_(NWs)/SA.Thirdly,SiC_(NWs) weakened the heat transfer by radiation at high temperatures.Therefore,SFs/SiC_(NWs)/SA presented remarkable thermal insulation(0.017 W(m K)^(-1) at 25℃,0.0287 W(m K)^(-1) at 500℃,and 0.094 W(m K)^(-1) at 1000℃).Besides,SFs/SiC_(NWs)/SA exhibited remarkable thermal stability(no size transform after being heat treated at 1000℃ for 1800 s)and tensile strength(0.75 MPa).These integrated properties made SFs/SiC_(NWs)/SA a promising candidate for highly efficient thermal insulators.展开更多
It is well known that adsorbent material is the key to determine the CO_(2)adsorption performance.Herein,ZIF-8 derived porous carbon(ZIF-8-C)is anchored into the framework of a novel composite aerogel(ZCPx),which util...It is well known that adsorbent material is the key to determine the CO_(2)adsorption performance.Herein,ZIF-8 derived porous carbon(ZIF-8-C)is anchored into the framework of a novel composite aerogel(ZCPx),which utilizes chitosan(CS)and polyvinyl alcohol(PVA)as raw materials.By controlling the ratio of ZIF-8-C,the developed hierarchical porous structures combine the advantages of micropores,mesopores,and macropores.Besides,the ligand material of ZIF-8-C and the amino group from CS are two sources of the high nitrogen content of ZCPx.The optimized sample ZCP4 shows a high nitrogen content of 6.78%,which can create more active centers and supply basic sites,thereby enhancing the CO_(2)adsorption capacity.Moreover,ZC P4 composite aerogel presents a CO_(2)adsorption capacity of2.26 mmol·g^(-1)(298 K,0.1 MPa)and CO_(2)/N_(2)selectivity(S_(CO_(2))/N_(2))can reach 20.02,and the dynamic breakthrough experiment is performed to confirm the feasibility of CO_(2)/N_(2)actual separation performance,proving that the composite aerogel is potential candidates for CO_(2)adsorption.展开更多
To optimize the preparation of alumina aerogels,the sol-gel method was combined with supercritical drying,using aluminum isopropoxide(AIP)as the precursor,ethanol(EtOH)as the solvent,and acetic acid(HAc)as the catalys...To optimize the preparation of alumina aerogels,the sol-gel method was combined with supercritical drying,using aluminum isopropoxide(AIP)as the precursor,ethanol(EtOH)as the solvent,and acetic acid(HAc)as the catalyst.The effects of the ethanol addition[n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:8:0.8:2,1:12:0.8:2,1:16:0.8:2,and 1:20:0.8:2]and acetic acid addition[n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:16:0.8:1,1:16:0.8:2,1:16:0.8:3,and 1:16:0.8:4]on the pore structure and specific surface area of Al_(2)O_(3) aerogels were studied.The results show that ethanol affects the pore structure of Al_(2)O_(3) aerogels by affecting the condensation probability of Al-OH troups,and acetic acid affects the pore structure of Al_(2)O_(3) aerogels by affecting the reaction rate;when n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:16:0.8:2,the Al_(2)O_(3) aerogel has a porous microstructure,and its internal pore diameters is generally smaller than the average free path of air molecules,showing excellent thermal insulation characteristics,low density of 0.20 g·cm^(-3),and the specific surface areas of 458,102,and 51 m^(2)·g^(-1) at 25,1000,and 1200℃,respectively.展开更多
Wearable pressure sensors capable of adhering comfortably to the skin hold great promise in sound detection.However,current intelligent speech assistants based on pressure sensors can only recognize standard languages...Wearable pressure sensors capable of adhering comfortably to the skin hold great promise in sound detection.However,current intelligent speech assistants based on pressure sensors can only recognize standard languages,which hampers effective communication for non-standard language people.Here,we prepare an ultralight Ti_(3)C_(2)T_(x)MXene/chitosan/polyvinylidene difluoride composite aerogel with a detection range of 6.25 Pa-1200 k Pa,rapid response/recovery time,and low hysteresis(13.69%).The wearable aerogel pressure sensor can detect speech information through the throat muscle vibrations without any interference,allowing for accurate recognition of six dialects(96.2%accuracy)and seven different words(96.6%accuracy)with the assistance of convolutional neural networks.This work represents a significant step forward in silent speech recognition for human–machine interaction and physiological signal monitoring.展开更多
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
The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion devices.Regulating the electronic structure of electrocatalysts by ligands has received partic...The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion devices.Regulating the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR electrocatalysts.Here,the surface electronic structure of Ptbased noble metal aerogels(NMAs)was modulated by various organic ligands,among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR electrocatalysis.Theoretical calculations suggested the smaller energy barrier for the transformation of O^(*) to OH^(*) and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals,thus enhancing the ORR intrinsic activity.Both Pt3Ni and Pt Pd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different media.Remarkably,the 4-methylphenylene modified Pt Pd aerogel exhibited the higher halfwave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/C.This work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.展开更多
Despite notable progress in thermoelectric(TE)materials and devices,developing TE aerogels with high-temperature resistance,superior TE performance and excellent elasticity to enable self-powered high-temperature moni...Despite notable progress in thermoelectric(TE)materials and devices,developing TE aerogels with high-temperature resistance,superior TE performance and excellent elasticity to enable self-powered high-temperature monitoring/warning in industrial and wearable applications remains a great challenge.Herein,a highly elastic,flame-retardant and high-temperature-resistant TE aerogel,made of poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube(PEDOT:PSS/SWCNT)composites,has been fabricated,displaying attractive compression-induced power factor enhancement.The as-fabricated sensors with the aerogel can achieve accurately pressure stimuli detection and wide temperature range monitoring.Subsequently,a flexible TE generator is assembled,consisting of 25 aerogels connected in series,capable of delivering a maximum output power of 400μW when subjected to a temperature difference of 300 K.This demonstrates its outstanding high-temperature heat harvesting capability and promising application prospects for real-time temperature monitoring on industrial high-temperature pipelines.Moreover,the designed self-powered wearable sensing glove can realize precise wide-range temperature detection,high-temperature warning and accurate recognition of human hand gestures.The aerogel-based intelligent wearable sensing system developed for firefighters demonstrates the desired self-powered and highly sensitive high-temperature fire warning capability.Benefitting from these desirable properties,the elastic and high-temperature-resistant aerogels present various promising applications including self-powered high-temperature monitoring,industrial overheat warning,waste heat energy recycling and even wearable healthcare.展开更多
The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fab...The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fabricated through filtration-induced delaminated gelation and ambient drying.The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber(FCNF)at the solid-liquid interface between the filter and the filtrate during filtration,resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding.By exchanging the solvents from water to hexane,the hydrogen bonding in the FCNF hydrogel is further enhanced,enabling the formation of the DAF with intra-layer mesopores upon ambient drying.The resulting aerogel film is lightweight and ultra-flexible,which pos-sesses desirable properties of high visible-light transmittance(91.0%),low thermal conductivity(33 mW m^(-1) K^(-1)),and high atmospheric-window emissivity(90.1%).Furthermore,the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups,enhancing its durability and UV resistance.Consequently,the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting,thermal insulation,and daytime radiative cooling under direct sunlight.Significantly,the enclosed space protected by the DAF exhibits a temperature reduction of 2.6℃ compared to that shielded by conventional architectural glass.展开更多
The fabrication of advanced graphene-based microwave absorbing materials with thin thickness,wide bandwidth,strong absorption strength,and low filling ratio remains a huge challenge.In this paper,nitrogen-doped reduce...The fabrication of advanced graphene-based microwave absorbing materials with thin thickness,wide bandwidth,strong absorption strength,and low filling ratio remains a huge challenge.In this paper,nitrogen-doped reduced graphene oxide/tricobalt tetraoxide(NRGO/Co_(3)O_(4))composite aerogels were syn-thesized by a three-step method of solvothermal reaction,high-temperature calcination,and hydrother-mal self-assembly.The results showed that the attained NRGO/Co_(3)O_(4)composite aerogels had a unique three-dimensional porous network structure,extremely low bulk density,and good compression recov-ery.Furthermore,the effect of the addition amounts of flower-like Co_(3)O_(4)on the complex dielectric con-stant and microwave absorption properties of NRGO/Co_(3)O_(4)composite aerogels was investigated.When the addition amount of Co_(3)O_(4)was equal to 15 mg,the prepared binary composite aerogel showed the strongest absorption strength of-62.78 dB and a wide absorption bandwidth of 5.5 GHz at a thin thick-ness of 2.13 mm and a low filling ratio of 15 wt.%.It was worth noting that the maximum absorption bandwidth could reach 6.32 GHz(11.68-18 GHz,spanning the entire Ku-band)at a thickness of 2.24 mm.In addition,the possible microwave absorption mechanism of NRGO/Co_(3)O_(4)composite aerogels was also proposed.Therefore,this paper will provide a new and simple strategy for preparing RGO-based porous nanocomposites as lightweight,efficient,and broadband microwave absorbers.展开更多
The conductive polymer poly(3,4-thylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)exhibits po-tential in the development of flexible devices due to its unique conjugated structure and water-solubility characteri...The conductive polymer poly(3,4-thylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)exhibits po-tential in the development of flexible devices due to its unique conjugated structure and water-solubility characteristics.To address the incompressibility of the original PEDOT:PSS aerogel without compromis-ing its high conductivity,a stable interpenetrating polymer network(IPN)was self-assembled by guiding the molecular motion within PEDOT:PSS and introducing multi-walled carbon nanotubes(MWCNTs).By combining critical surface removal,directional freeze-drying,and polydimethylsiloxane(PDMS)reinforce-ment processes,a hydrophobic PDMS@MWCNTs/PP aerogel with a highly oriented porous structure and high strength was prepared.Under the synergistic effect of MWCNTs/PEDOT:PSS electroactive scaffold,the composite aerogel exhibited a high sensitivity of up to 16.603 kPa^(-1) at 0-2 kPa,a fast response time of 74 ms,and excellent repeatability.Moreover,the sensor possessed hydrophobicity with a good water contact angle of 137°The sensor could serve as a wearable electronic monitoring device to achieve ac-curate and sensitive detection of human motion including large-scale human activities and tiny muscle movements.Therefore,our findings provide a new direction to fabricate high-performance piezoresistive sensors based on three-dimensional(3D)conductive polymer active scaffolds,demonstrating their great potential for flexible electronics,human-computer interaction,and a wide range of applications under special working conditions.展开更多
Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is presented.In situ formed flower-like CaCO_(3)molecularly embedde...Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is presented.In situ formed flower-like CaCO_(3)molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was maintained.The homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization catalyst.The decomposition of the homogenously distributed CaCO_(3)during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical performance.At 0.5 mA cm^(-2),the gravimetric capacitance increased from 0.01 F g^(-1)without mineralization to 322 F g^(-1)with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon electrodes.An outstanding cycling stability of~104%after 1000 cycles in 1 M HClO4 was demonstrated.The assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g^(-1)and a high energy density of 26 W h kg^(-1)at a power density of 4000 W kg^(-1),with excellent cycling performance(98.5%retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary shapes.Furthermore,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.展开更多
The well-designed composite with satisfactory electromagnetic microwave absorption at high temperatures remains a serious challenge.Herein,we fabricated a resorcinol-formaldehyde/silica dioxide composite aerogel(RF/Si...The well-designed composite with satisfactory electromagnetic microwave absorption at high temperatures remains a serious challenge.Herein,we fabricated a resorcinol-formaldehyde/silica dioxide composite aerogel(RF/SiO_(2))with a three-dimensional network structure using sol-gel,atmospheric pressure drying technique as well as heat-treated processes to achieve enhanced microwave absorption capabilities in the low frequency range.The pristine RF/SiO_(2)aerogel presented a typical micropores structure with a surface area,porous volume,and density of 146.82 m^(2)/g,62.40%,and 0.28 cm^(3)/g,respectively.Remarkably,the RF/SiO_(2)aerogel showed an effective absorption bandwidth of 3.56 GHz and a minimum reflection loss value of-46.10 d B at 2.25 mm after being heat-treated at 1500°C,while the maximum effective absorption bandwidth was 3.60 GHz at 2.30 mm.The intricate three-dimensional networks possessed remarkable impedance matching,multiple attenuation mechanisms,interfacial polarization,and dielectric loss,which were attributed to the exceptional ability to absorb electromagnetic microwaves.It offered a fresh approach to creating adaptable and effective microwave absorption materials in military defense.展开更多
Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, ma...Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, prediction of their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed a cross-aligned and cubic pore model(CACPM) based on the actual pore arrangement of SiO_(2) aerogel. Based on the established CACPM, the effective thermal conductivity expression for the aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of T = 298 K, a_(2)= 0.85, D_(1)= 90 μm, ρ = 128 kg/m^(3), within the pressure range of 0–10^(5)Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 10^(3)–10^(4)Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer models and calculation formulae.展开更多
基金the financial support provided by the National Natural Science Foundation of China(Nos.22175094,21971113)。
文摘Covalent organic frameworks(COFs)have great potential as adsorbents due to their customizable functionality,low density and high porosity.However,COFs powder exists with poor processing and recycling performance.Moreover,due to the accumulation of COFs nanoparticles,it is not conducive to the full utilization of their surface functional groups.Currently,the strategy of COFs assembling into aerogel can be a good solution to this problem.Herein,we successfully synthesize composite aerogels(CSR)by in-situ self-assembly of two-dimensional COFs and graphene based on crosslinking of sodium alginate.Sodium alginate in the composite improves the mechanical properties of the aerogel,and graphene provides a template for the in-situ growth of COFs.Impressively,CSR aerogels with different COFs and sizes can be prepared by changing the moiety of the ligand and modulating the addition amount of COFs.The prepared CSR aerogels exhibit porous,low density,good processability and good mechanical properties.Among them,the density of CSR-N-1.6 is only 5 mg/cm3,which is the lowest density among the reported COF aerogels so far.Due to these remarkable properties,CSR aerogels perform excellent adsorption and recycling properties for the efficient and rapid removal of organic pollutants(organic dyes and antibiotics)from polluted water.In addition,it is also possible to visually recognize the presence of antibiotics by fluorescence detection.This work not only provides a new strategy for synthesizing COF aerogels,but also accelerates the practical application of COF aerogels and contributes to environmental remediation.
基金the National Natural Science Foundation of China(52090034,52273064,52221006)the Fundamental Research Funds for the Central Universities(JD2417)is gratefully acknowledged.
文摘Although multifunctional electromagnetic interference(EMI)shielding materials with ultrahigh electromagnetic wave absorption are highly required to solve increasingly serious electromagnetic radiation and pollution and meet multi-scenario applications,EMI shielding materials usually cause a lot of reflection and have a single function.To realize the broadband absorption-dominated EMI shielding via absorption-reflection-reabsorption mechanisms and the interference cancelation effect,multifunctional asymmetric bilayer aerogels are designed by sequential printing of a MXene-graphene oxide(MG)layer with a MG emulsion ink and a conductive MXene layer with a MXene ink and subsequent freeze-drying for generating and solidifying numerous pores in the aerogels.The top MG layer of the asymmetric bilayer aerogel optimizes impedance matching and achieves re-absorption,while the bottom MXene layer enhances the reflection of the incident electromagnetic waves.As a result,the asymmetric bilayer aerogel achieves an average absorption coefficient of 0.95 in the X-band and shows the tunable absorption ability to electromagnetic wave in the ultrawide band from 8.2 to 40 GHz.Finite element simulations substantiate the effectiveness of the asymmetric bilayer aerogel for electromagnetic wave absorption.The multifunctional bilayer aerogels exhibit hydrophobicity,thermal insulation and Joule heating capacities and are efficient in solar-thermal/electric heating,infrared stealth,and clean-up of spilled oil.
基金financially supported by the National Natural Science Foundation of China(Nos.52073214 and 22075211)Guangxi Natural Science Fund for Distinguished Young Scholars(No.2024GXNSFFA010008)+5 种基金Natural Science Foundation of Shandong Province(Nos.ZR2023MB049 and ZR2021QB129)China Postdoctoral Science Foundation(No.2020M670483)Science Foundation of Weifang University(No.2023BS11)supported by the open research fund of the Laboratory of Xinjiang Native Medicinal and Edible Plant Resources Chemistry at Kashi Universitysupported by the Tianhe Qingsuo Open Research Fund of TSYS in 2022 and NSCC-TJNankai University Large-scale Instrument Experimental Technology R&D Project(No.21NKSYJS09)。
文摘Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.
基金supported by the National Natural Science Foundation of China(No.22265021)the Aeronautical Science Foundation of China(No.2020Z056056003)。
文摘Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.
基金supported by the National Natural Science Foundation of China(Nos.92371110 and 52373281)Weiqiao Science Foundation(H2872302 and H2872303)the Scientific Research Innovation Capability Support Project for Young Faculty.
文摘Ceramic aerogels(CAs)have emerged as a significant research frontier across various applications due to their lightweight,high porosity,and easily tunable structural characteristics.However,the intrinsic weak interactions among the constituent nanoparticles,coupled with the limited toughness of traditional CAs,make them susceptible to structural collapse or even catastrophic failure when exposed to complex mechanical external forces.Unlike 0D building units,1D ceramic nanofibers(CNFs)possess a high aspect ratio and exceptional flexibility simultaneously,which are desirable building blocks for elastic CAs.This review presents the recent progress in electrospun ceramic nanofibrous aerogels(ECNFAs)that are constructed using ECNFs as building blocks,focusing on the various preparation methods and corresponding structural characteristics,strategies for optimizing mechanical performance,and a wide range of applications.The methods for preparing ECNFs and ECNFAs with diverse structures were initially explored,followed by the implementation of optimization strategies for enhancing ECNFAs,emphasizing the improvement of reinforcing the ECNFs,establishing the bonding effects between ECNFs,and designing the aggregate structures of the aerogels.Moreover,the applications of ECNFAs across various fields are also discussed.Finally,it highlights the existing challenges and potential opportunities for ECNFAs to achieve superior properties and realize promising prospects.
基金supported by the National Natural Science Foundation of China(No.52233003)the Department of Sichuan Province(No.2022JDJQ0023)。
文摘As the application scenarios of aerogels expand,higher requirements are put forward for the materials used to prepare aerogels.Due to the unique chemical structure,polytetrafluoroethylene(PTFE)has excellent properties such as high-temperature resistance,hydrophobicity,and chemical stability.However,the PTFE aerogels are difficult to be molded due to the weak interaction between resin particles.In this work,poly(ethylene oxide)(PEO)was selected as the carrier to assist the PTFE aerogels molding.The pure PTFE aerogels were prepared by homogeneously mixing PTFE aqueous dispersion and PEO,freeze-drying,and high-temperature sintering.When the mass fraction of PTFE and PEO were appropriate,the porosity of PTFE aerogels exceeded 90%and had a hierarchical honeycomb structure.Results showed that the PTFE aerogels not only had excellent hydrophobicity but also possessed superior acoustic insulation,mechanical strength,thermal insulation,and heat resistance properties.Specifically,the water contact angle is about 140°.The noise reduction coefficient is 0.34 and the average sound absorption coefficient is greater than 88%in the frequency range of 2000-6400 Hz.Meanwhile,the thermal conductivity in the air is about 0.045 W/(m·K),and the initial thermal decomposition temperature is 450℃.More importantly,the PTFE aerogels had excellent temperature and corrosion resistance.Even after extremely thermal and chemical treatment,they remained unchanged porous structure as well as acoustic and thermal insulation properties,which exhibits great potential for application in many harsh environments.
基金supported by the National Key R&D Program of China(No.2022YFC3702800).
文摘Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages,such as fine building block size together with high specific surface area,abundant pore structure,etc.Additionally,monolithic aerogels possess a unique monolithic macrostructure that sets them apart from aerogel powders and nanoparticles in practical environmental clean-up applications.This review delves into the available synthesis strategies and atmospheric environmental applications of monolithic aerogels,covering types of monolithic aerogels including SiO_(2),graphene,metal oxides and their combinations,along with their preparation methods.In particular,recent developments for VOC adsorption,CO_(2)capture,catalytic oxidation of VOCs and catalytic reduction of CO_(2)are highlighted.Finally,challenges and future opportunities for monolithic aerogels in the atmospheric environmental purification field are proposed.This reviewprovides valuable insights for designing and utilizing monolithic aerogel-based functional materials.
基金supported by the National Natural Science Foun-dation of China(Grant No.U2167214).
文摘Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica aerogels decreased greatly caused by transparency to heat radiation.Opacifiers introduced into silica sol can block heat radiation yet destroy the uniformity of aerogels.Herein,we designed and prepared a silica aerogel composite with oriented and layered silica fibers(SFs),SiC nanowires(SiC_(NWs)),and silica aerogels,which were prepared by papermaking,chemical vapor infiltration(CVI),and sol-gel respectively.Firstly,oriented and layered SFs made still air a wall to block heat transfer by the solid phase.Secondly,SiC_(NWs) were grown in situ on the surface of SFs evenly to weave into the network,and the network reduced the gaseous thermal conductivity by dividing cracks in SFs/SiC_(NWs)/SA.Thirdly,SiC_(NWs) weakened the heat transfer by radiation at high temperatures.Therefore,SFs/SiC_(NWs)/SA presented remarkable thermal insulation(0.017 W(m K)^(-1) at 25℃,0.0287 W(m K)^(-1) at 500℃,and 0.094 W(m K)^(-1) at 1000℃).Besides,SFs/SiC_(NWs)/SA exhibited remarkable thermal stability(no size transform after being heat treated at 1000℃ for 1800 s)and tensile strength(0.75 MPa).These integrated properties made SFs/SiC_(NWs)/SA a promising candidate for highly efficient thermal insulators.
基金supported by the Natural Science Foundation of Shandong Province(ZR2021ME124,ZR2023ME033)Science-Education-Industry Integration Innovation Pilot Project of Qilu University of Technology(2024GH09)+2 种基金Innovation Capacity Improvement Project of Small and Medium-Sized Technology-Based Enterprise of Shandong Province(2023TSGC0706,2022TSGC1022)Technological Innovation Projects of Shandong Province(202350700179,202351600213)Science and technology plan project of Shandong Railway Investment Holding Group(TTKJ2023-01)。
文摘It is well known that adsorbent material is the key to determine the CO_(2)adsorption performance.Herein,ZIF-8 derived porous carbon(ZIF-8-C)is anchored into the framework of a novel composite aerogel(ZCPx),which utilizes chitosan(CS)and polyvinyl alcohol(PVA)as raw materials.By controlling the ratio of ZIF-8-C,the developed hierarchical porous structures combine the advantages of micropores,mesopores,and macropores.Besides,the ligand material of ZIF-8-C and the amino group from CS are two sources of the high nitrogen content of ZCPx.The optimized sample ZCP4 shows a high nitrogen content of 6.78%,which can create more active centers and supply basic sites,thereby enhancing the CO_(2)adsorption capacity.Moreover,ZC P4 composite aerogel presents a CO_(2)adsorption capacity of2.26 mmol·g^(-1)(298 K,0.1 MPa)and CO_(2)/N_(2)selectivity(S_(CO_(2))/N_(2))can reach 20.02,and the dynamic breakthrough experiment is performed to confirm the feasibility of CO_(2)/N_(2)actual separation performance,proving that the composite aerogel is potential candidates for CO_(2)adsorption.
文摘To optimize the preparation of alumina aerogels,the sol-gel method was combined with supercritical drying,using aluminum isopropoxide(AIP)as the precursor,ethanol(EtOH)as the solvent,and acetic acid(HAc)as the catalyst.The effects of the ethanol addition[n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:8:0.8:2,1:12:0.8:2,1:16:0.8:2,and 1:20:0.8:2]and acetic acid addition[n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:16:0.8:1,1:16:0.8:2,1:16:0.8:3,and 1:16:0.8:4]on the pore structure and specific surface area of Al_(2)O_(3) aerogels were studied.The results show that ethanol affects the pore structure of Al_(2)O_(3) aerogels by affecting the condensation probability of Al-OH troups,and acetic acid affects the pore structure of Al_(2)O_(3) aerogels by affecting the reaction rate;when n(AIP):n(EtOH):n(H_(2)O):n(HAc)=1:16:0.8:2,the Al_(2)O_(3) aerogel has a porous microstructure,and its internal pore diameters is generally smaller than the average free path of air molecules,showing excellent thermal insulation characteristics,low density of 0.20 g·cm^(-3),and the specific surface areas of 458,102,and 51 m^(2)·g^(-1) at 25,1000,and 1200℃,respectively.
基金supported by the National Nature Science Foundation of China(No.62122030,62333008,62371205,52103208)National Key Research and Development Program of China(No.2021YFB3201300)+1 种基金Application and Basic Research of Jilin Province(20130102010 JC)Fundamental Research Funds for the Central Universities,Jilin Provincial Science and Technology Development Program(20230101072JC)。
文摘Wearable pressure sensors capable of adhering comfortably to the skin hold great promise in sound detection.However,current intelligent speech assistants based on pressure sensors can only recognize standard languages,which hampers effective communication for non-standard language people.Here,we prepare an ultralight Ti_(3)C_(2)T_(x)MXene/chitosan/polyvinylidene difluoride composite aerogel with a detection range of 6.25 Pa-1200 k Pa,rapid response/recovery time,and low hysteresis(13.69%).The wearable aerogel pressure sensor can detect speech information through the throat muscle vibrations without any interference,allowing for accurate recognition of six dialects(96.2%accuracy)and seven different words(96.6%accuracy)with the assistance of convolutional neural networks.This work represents a significant step forward in silent speech recognition for human–machine interaction and physiological signal monitoring.
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(22374119,21902128)the China Postdoctoral Science Foundation(2021M692620)+1 种基金the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(2021-QZ-01)the Key Project of Natural Science Fund of Shaanxi Province(2023-JC-ZD-06)。
文摘The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion devices.Regulating the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR electrocatalysts.Here,the surface electronic structure of Ptbased noble metal aerogels(NMAs)was modulated by various organic ligands,among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR electrocatalysis.Theoretical calculations suggested the smaller energy barrier for the transformation of O^(*) to OH^(*) and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals,thus enhancing the ORR intrinsic activity.Both Pt3Ni and Pt Pd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different media.Remarkably,the 4-methylphenylene modified Pt Pd aerogel exhibited the higher halfwave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/C.This work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation(2022A1515110296,2022A1515110432)the Shenzhen Science and Technology Program(20231120171032001)the National Natural Science Foundation of China(No.52242305).
文摘Despite notable progress in thermoelectric(TE)materials and devices,developing TE aerogels with high-temperature resistance,superior TE performance and excellent elasticity to enable self-powered high-temperature monitoring/warning in industrial and wearable applications remains a great challenge.Herein,a highly elastic,flame-retardant and high-temperature-resistant TE aerogel,made of poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube(PEDOT:PSS/SWCNT)composites,has been fabricated,displaying attractive compression-induced power factor enhancement.The as-fabricated sensors with the aerogel can achieve accurately pressure stimuli detection and wide temperature range monitoring.Subsequently,a flexible TE generator is assembled,consisting of 25 aerogels connected in series,capable of delivering a maximum output power of 400μW when subjected to a temperature difference of 300 K.This demonstrates its outstanding high-temperature heat harvesting capability and promising application prospects for real-time temperature monitoring on industrial high-temperature pipelines.Moreover,the designed self-powered wearable sensing glove can realize precise wide-range temperature detection,high-temperature warning and accurate recognition of human hand gestures.The aerogel-based intelligent wearable sensing system developed for firefighters demonstrates the desired self-powered and highly sensitive high-temperature fire warning capability.Benefitting from these desirable properties,the elastic and high-temperature-resistant aerogels present various promising applications including self-powered high-temperature monitoring,industrial overheat warning,waste heat energy recycling and even wearable healthcare.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.52273067,52122303,52233006)the Fundamental Research Funds for the Central Universities(Grant No.2232023A-03)the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(23SG29).
文摘The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fabricated through filtration-induced delaminated gelation and ambient drying.The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber(FCNF)at the solid-liquid interface between the filter and the filtrate during filtration,resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding.By exchanging the solvents from water to hexane,the hydrogen bonding in the FCNF hydrogel is further enhanced,enabling the formation of the DAF with intra-layer mesopores upon ambient drying.The resulting aerogel film is lightweight and ultra-flexible,which pos-sesses desirable properties of high visible-light transmittance(91.0%),low thermal conductivity(33 mW m^(-1) K^(-1)),and high atmospheric-window emissivity(90.1%).Furthermore,the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups,enhancing its durability and UV resistance.Consequently,the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting,thermal insulation,and daytime radiative cooling under direct sunlight.Significantly,the enclosed space protected by the DAF exhibits a temperature reduction of 2.6℃ compared to that shielded by conventional architectural glass.
基金supported by the Natural Science Research Project of Anhui Educational Committee(No.KJ2021ZD0047)the Joint National-Local Engineering Research Center for Safe and Precise Coal Mining Fund(No.EC2022020)+1 种基金the Anhui Provincial Natural Science Foundation(No.2008085J27)the Anhui Provincial Training Program of Innovation and Entrepreneurship for Undergraduates(No.S202210361156).
文摘The fabrication of advanced graphene-based microwave absorbing materials with thin thickness,wide bandwidth,strong absorption strength,and low filling ratio remains a huge challenge.In this paper,nitrogen-doped reduced graphene oxide/tricobalt tetraoxide(NRGO/Co_(3)O_(4))composite aerogels were syn-thesized by a three-step method of solvothermal reaction,high-temperature calcination,and hydrother-mal self-assembly.The results showed that the attained NRGO/Co_(3)O_(4)composite aerogels had a unique three-dimensional porous network structure,extremely low bulk density,and good compression recov-ery.Furthermore,the effect of the addition amounts of flower-like Co_(3)O_(4)on the complex dielectric con-stant and microwave absorption properties of NRGO/Co_(3)O_(4)composite aerogels was investigated.When the addition amount of Co_(3)O_(4)was equal to 15 mg,the prepared binary composite aerogel showed the strongest absorption strength of-62.78 dB and a wide absorption bandwidth of 5.5 GHz at a thin thick-ness of 2.13 mm and a low filling ratio of 15 wt.%.It was worth noting that the maximum absorption bandwidth could reach 6.32 GHz(11.68-18 GHz,spanning the entire Ku-band)at a thickness of 2.24 mm.In addition,the possible microwave absorption mechanism of NRGO/Co_(3)O_(4)composite aerogels was also proposed.Therefore,this paper will provide a new and simple strategy for preparing RGO-based porous nanocomposites as lightweight,efficient,and broadband microwave absorbers.
基金supported by the Xi’an Science and Technology Plan Project(Nos.GXYD14.27 and GX2338)the Key Scientific Research Program of Shaanxi Provincial Depart-ment of Education(Nos.22JY046 and 21JY032)+1 种基金the Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Tech-nology of North University of China(No.XJZZ202104)the General Project of Natural Science Basic Research Program of Shaanxi Provincial Department of Science and Technology(No.2023-JC-YB-424)。
文摘The conductive polymer poly(3,4-thylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)exhibits po-tential in the development of flexible devices due to its unique conjugated structure and water-solubility characteristics.To address the incompressibility of the original PEDOT:PSS aerogel without compromis-ing its high conductivity,a stable interpenetrating polymer network(IPN)was self-assembled by guiding the molecular motion within PEDOT:PSS and introducing multi-walled carbon nanotubes(MWCNTs).By combining critical surface removal,directional freeze-drying,and polydimethylsiloxane(PDMS)reinforce-ment processes,a hydrophobic PDMS@MWCNTs/PP aerogel with a highly oriented porous structure and high strength was prepared.Under the synergistic effect of MWCNTs/PEDOT:PSS electroactive scaffold,the composite aerogel exhibited a high sensitivity of up to 16.603 kPa^(-1) at 0-2 kPa,a fast response time of 74 ms,and excellent repeatability.Moreover,the sensor possessed hydrophobicity with a good water contact angle of 137°The sensor could serve as a wearable electronic monitoring device to achieve ac-curate and sensitive detection of human motion including large-scale human activities and tiny muscle movements.Therefore,our findings provide a new direction to fabricate high-performance piezoresistive sensors based on three-dimensional(3D)conductive polymer active scaffolds,demonstrating their great potential for flexible electronics,human-computer interaction,and a wide range of applications under special working conditions.
基金financially supported by the European Research Council under the Horizon 2020 framework programme(Grant No.772370-PHOENEEX)
文摘Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is presented.In situ formed flower-like CaCO_(3)molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was maintained.The homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization catalyst.The decomposition of the homogenously distributed CaCO_(3)during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical performance.At 0.5 mA cm^(-2),the gravimetric capacitance increased from 0.01 F g^(-1)without mineralization to 322 F g^(-1)with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon electrodes.An outstanding cycling stability of~104%after 1000 cycles in 1 M HClO4 was demonstrated.The assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g^(-1)and a high energy density of 26 W h kg^(-1)at a power density of 4000 W kg^(-1),with excellent cycling performance(98.5%retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary shapes.Furthermore,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.
基金supported by the Fundamental Research Funds for the Central Universities(Grant Nos.D5000210522 and D5000210517)China Postdoctoral Science Foundation(Grant No.2021M702665)+2 种基金Natural Science Foundation of Shaanxi Province(Grant Nos.2022JQ-482 and 2023-JC-QN-0380)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021A1515111155,2022A1515111200 and 2022A1515011191)Basic Research Programs of Taicang(Grant Nos.TC2021JC01,TC2021JC21,and TC2022JC08)。
文摘The well-designed composite with satisfactory electromagnetic microwave absorption at high temperatures remains a serious challenge.Herein,we fabricated a resorcinol-formaldehyde/silica dioxide composite aerogel(RF/SiO_(2))with a three-dimensional network structure using sol-gel,atmospheric pressure drying technique as well as heat-treated processes to achieve enhanced microwave absorption capabilities in the low frequency range.The pristine RF/SiO_(2)aerogel presented a typical micropores structure with a surface area,porous volume,and density of 146.82 m^(2)/g,62.40%,and 0.28 cm^(3)/g,respectively.Remarkably,the RF/SiO_(2)aerogel showed an effective absorption bandwidth of 3.56 GHz and a minimum reflection loss value of-46.10 d B at 2.25 mm after being heat-treated at 1500°C,while the maximum effective absorption bandwidth was 3.60 GHz at 2.30 mm.The intricate three-dimensional networks possessed remarkable impedance matching,multiple attenuation mechanisms,interfacial polarization,and dielectric loss,which were attributed to the exceptional ability to absorb electromagnetic microwaves.It offered a fresh approach to creating adaptable and effective microwave absorption materials in military defense.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51764046 and 52160013)the Inner Mongolia Autonomous Region Postgraduate Research Innovation Project of China (Grant No. S20231165Z)the Research Program of Science and Technology at Universities of Inner Mongolia Autonomous Region of China (Grant Nos. 2023RCTD016 and 2024RCTD008)。
文摘Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, prediction of their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed a cross-aligned and cubic pore model(CACPM) based on the actual pore arrangement of SiO_(2) aerogel. Based on the established CACPM, the effective thermal conductivity expression for the aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of T = 298 K, a_(2)= 0.85, D_(1)= 90 μm, ρ = 128 kg/m^(3), within the pressure range of 0–10^(5)Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 10^(3)–10^(4)Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer models and calculation formulae.
