The acoustic performance for the nanoporous frustule of the diatom is studied based on the computational fluid dynamics theory and acoustic theory involved.Representative Coscinodiscus sp.frustule is observed through ...The acoustic performance for the nanoporous frustule of the diatom is studied based on the computational fluid dynamics theory and acoustic theory involved.Representative Coscinodiscus sp.frustule is observed through the scanning electron microscope and modeled by the commercial software Solidworks.Further,the acoustic performance for the Coscinodiscus sp.frustule is studied at the varied depth,diameter or interval of the pore,as well as the film thickness of the fluid surrounding the Coscinodiscus sp.frustule.The numerical results show that,when the upper and lower pore diameters are separately 200 and 300 nm,the upper and lower pore depths are separately 200 and 250 nm,and both the pore interval and fluid film thickness are 500 nm,the elaborate nanoporous structure of Coscinodiscus sp.frustule can lower its acoustic power level by 17.49%,compared with that without porous structure.Meanwhile,the double-layer pore of Coscinodiscus sp.frustule can decrease its acoustic power level by 12.69%,compared with its single-layer pore structures.展开更多
The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-...The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x),in situ grown on nickel foam(NF),holds great promise as a high-efficient bifunctional electrocatalyst(named R-CoFe/Ce/NF)for water splitting.Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization.By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_(2−x) heterostructure interfaces,the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution(η_(10)=227 mV;η_(500)=450 mV)and hydrogen evolution(η_(10)=35 mV;η_(408)=560 mV)reactions with high normalized electrochemical active surface areas,respectively.Additionally,the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm^(−2) only at 1.75 V;the decline of activity is satisfactory after 100-h durability test at 300 mA·cm^(−2).Density functional theory also demonstrates that the electron can transfer from CeO_(2−x) by virtue of O atom to CoFeOOH at CoFeOOH/CeO_(2−x) heterointerfaces and enhancing the adsorption of reactant,thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting.展开更多
Retaining satisfactory electrocatalytic performance under high current density plays a crucial role in industrial water splitting but is still limited to the enormous energy loss because of insufficient exposure of ac...Retaining satisfactory electrocatalytic performance under high current density plays a crucial role in industrial water splitting but is still limited to the enormous energy loss because of insufficient exposure of active sites caused by the blocked mass/charge transportation at this condition.Herein,we present a freestanding lamellar nanoporous Ni-Co-Mn alloy electrode(Lnp-NCM)designed by a refined variant of the“dealloying-coarsening-dealloying”protocol for highly efficient bifunctional electrocatalyst,where large porous channels distribute on the surface and small porous channels at the interlayer.With its 3D lamellar architecture regulating,the electrocatalytic properties of the electrodes with different distances between lamellas are compared,and faster energy conversion kinetics is achieved with efficient bubble transport channels and abundant electroactive sites.Note that the optimized sample(Lnp-NCM4)is expected to be a potential bifunctional electrocatalyst with low overpotentials of 258 and 439 mV at high current densities of 1000 and 900 mA·cm^(-2)for hydrogen and oxygen evolution reactions(HER and OER),respectively.During overall water splitting in a two-electrode cell with Lnp-NCM4 as cathode and anode,it only needs an ultralow cell voltage of 1.75 V to produce 100 mA·cm^(-2)with remarkable long-term stability over 50 h.This study on lamellar nanoporous electrode design approaches industrial water splitting requirements and paves a way for developing other catalytic systems.展开更多
The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature c...The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature chemical corrosion, low and high current level electrochemical corrosion, four types of porous structures, including uneven corrosion pits, hybrid porous, haystack type and bicontinuous model were prepared by chemically and electrochemically dealloying the porous Cu-34.6%Mn alloy made by the Gasar process. Then, the surface diffusion coefficient(DS) and the diffusion frequency(kD) of Cu atom, as well as the dissolution frequency(kE) of Mn atom were calculated with dealloying condition. The dealloyed morphologies for room temperature chemical corrosion and low current level electrochemical corrosion were similar due to the same DS. While the dealloyed structures changed from bulk hybrid porous structure to bicontinuous porous film with decreasing kD/kE.展开更多
Although an increasing interest has been attracted to further develop heterostructured catalysts from metallic glasses(MGs) by heat treatment, overcoming surface oxidation effect is still a critical problem for such e...Although an increasing interest has been attracted to further develop heterostructured catalysts from metallic glasses(MGs) by heat treatment, overcoming surface oxidation effect is still a critical problem for such environmental catalysts. Herein, a short-time electrochemical etching of partially crystallized Febased ribbons in 0.3 M H3 PO4 electrolyte enables the formation of honeycomb-like nanoporous structure as effective catalytic active sites in Fenton-like process. Studies of structure and surface morphologies reveal that the formation of nanoporous structure by potentiostatic etching originates from electrochemical potential difference of nanocrystals(a-Fe(Si) and Fe2 B) and residual amorphous phase in partially crystallized ribbons, where Fe2 B having a lower open circuit potential tends to be selectively dissolved.Simultaneously, thin oxide layer after electrochemical etching exposes more active sites for H2 O2 activation and provides an effective protection of nanocrystals from massive loss during etching. Investigation of optimal processing conditions suggests that the selection of electrolyte plays an important role;dye degradation rates of etched ribbons in HNO3 and Na2 SO4 electrolytes can also achieve at least 2 times higher than that of as-annealed ribbons. This work holds the promise to develop novel environmental catalysts by effective electrochemical etching of partially crystallized ribbons.展开更多
Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in o...Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.展开更多
The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black sha...The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller （BET）, Dubinin-Radushkevich （DR）, t-plot, Barrett- Joyner-Halenda （BJH） and density functional theory （DFT） methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that （1） The Lower Silurian shale has high TOC content of 0.92%~96%, high quartz content of 30.6%-69.5%, and high clays content of 24.1%-51.2%. The total specific surface area varies from 7.56 m^2/g to 25.86 m^2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. （2） Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. （3） A combination of N2 and CO2 adsorption provides the most suitable detection range （~0.3-60 nm） and has high reliability and accuracy for nanopore structure characterization. （4） The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.展开更多
High entropy alloys(HEAs)containing five or more equimolar components have shown promising catalytic performance due to their unique chemical and mechanical properties.However,it is still challenging to prepare scalab...High entropy alloys(HEAs)containing five or more equimolar components have shown promising catalytic performance due to their unique chemical and mechanical properties.However,it is still challenging to prepare scalable and efficient nanoporous HEAs as catalysts.Here,we present a facile strategy to synthesize largescale nanoporous HEAs particles by combing vacuum induction melting,gas atomization,and acidic etching procedure.The application of HEAs to energy conversion is evaluated with electrocatalytic oxygen evolution reaction(OER)on AlCrCuFeNi HEAs.The HEAs exhibit a low OER overpotential of 270 mV to achieve a current density of 10 mA·cm^(-2),a small Tafel slope of 77.5 mV·dec^(-1),and long-term stability for over 35 h in 1 mol·L^(-1) KOH,which is comparable to the state-of-the-art OER electrocatalyst RuO2.The findings in this paper not only provide an industrial approach to produce nanoporous HEAs powder but also inspire the applications of HEAs as catalysts.展开更多
The frost-driven self-fracture of ionomer-bound carbon electrodes compromises the mechanical stability of electrochemical systems under subzero conditions.This study suggests that the mechanical degradation of ionomer...The frost-driven self-fracture of ionomer-bound carbon electrodes compromises the mechanical stability of electrochemical systems under subzero conditions.This study suggests that the mechanical degradation of ionomer-bound carbon electrodes under subfreezing conditions is primarily driven by damage within the ionomer binder phase rather than within the nanopores.This damage occurs owing to the expansion of confined water upon freezing.Reducing the size of the freezable water domains significantly enhances the mechanical robustness.Structural and mechanical analyses reveal that thermal reconfiguration effectively modifies the ionomer nanostructure,leading to an approximately 30%reduction in water uptake and improved resistance to frost-induced self-fracturing.Nanostructural analyses further confirm that crystallized packing in the ionomer binder minimizes the number of water retention sites,thereby restricting the buildup of internal stress during freezing.Consequently,the elongation of the as-prepared electrodes reduces by approximately 65%after freezing at−10℃,whereas that of the thermally reconfigured electrodes is above 90%of its initial value with minimal deterioration.These findings highlight the critical role of ionomer-phase engineering in improving the low-temperature durability of ionomer-bound carbon electrodes,providing a scalable strategy applicable to fuel cells,water electrolyzers,and next-generation energy storage systems without requiring antifreezing agents.展开更多
Nanoporous metamaterials have garnered significant attention due to their unique combination of lightweight,high specific-surface-area,and small size effects.However,their mechanical performance is usually limited by ...Nanoporous metamaterials have garnered significant attention due to their unique combination of lightweight,high specific-surface-area,and small size effects.However,their mechanical performance is usually limited by structural imperfections introduced during conventional fabrication processes.In this study,we present a universal and cost-effective thermomechanical molding technique for directly fabricating three-dimensional(3D)crystalline metamaterials.Micropillar compression tests show that the nanoporous structures fabricated through this technique exhibit significantly enhanced mechanical properties,even with a yield strength 2 times higher than that of the corresponding bulk materials.Transmission electron microscope(TEM)characterization revealed the single-crystalline nature of the whole nanoporous structure,which can fully utilize the size effect of strength,that is,“the smaller the stronger”,thereby offsetting the reduction of effective load-bearing materials caused by porosity.Moreover,we demonstrate that the thermomechanical molding technique is highly versatile,enabling the fabrication of 3D nanoporous structures in a wide range of elemental metals,thermoelectric,semiconductor,and phase-change materials,offering a promising way for the development of next-generation functional nanoporous metamaterials.展开更多
The high electrical conductivity and high specific surface area of graphene are traditionally regarded as the most intriguing features for its promise as the electrode material for supercapacitors. In this perspective...The high electrical conductivity and high specific surface area of graphene are traditionally regarded as the most intriguing features for its promise as the electrode material for supercapacitors. In this perspective, we highlight that from the engineering point of view, the unique colloidal chemistry of chemically functionalized graphene is the key property that has made graphene stand out as a promising nanoscale building block for constructing unique nanoporous electrodes for capacitive energy storage, We present several examples to demonstrate bow the non-covalent colloidal forces between graphene sheets can be harnessed to engineer the nanostructure of graphene-based bulk electrodes for supercapacitors based on both the electrical double layer storage and the redox reaction or pseudo-capacitance mechanisms. The colloidal engineering strategy can be extended to enable other nanomaterials to achieve high energy storage performance.展开更多
The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermo...The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermoelectric devices and near-field imaging systems.In this paper,we design three structures(multilayer structure,nanoporous structure,and nanorod structure)based on high-entropy alloys to realize the enhancement of NFRHT.By combining stochastic electrodynamicsand Maxwell-Garnett's description of the effective medium,we calculate the radiative heat transfer under different parametersand find that the nanoporousstructure has the largest enhancement effect on NFRHT.The near-field heat transfer factor(q)of this structure(q=1.40×10^(9)W/(m^(2)·K))is three times higher than that of the planestructure(q=4.6×10^(8)W/(m^(2)·K)),and about two orders of magnitude higher than that of the SiO2plate.Thisresult providesa freshidea for the enhancement of NFRHT and will promote the application of high-entropy alloy materials in near-field heat radiation.展开更多
High entropy alloys(HEAs)have garnered significant attention due to their distinctive properties,while their precise regulation remains at infancy stage.Herein,we report PtSnBiPdIn HEA nanoparticles with tensilestrain...High entropy alloys(HEAs)have garnered significant attention due to their distinctive properties,while their precise regulation remains at infancy stage.Herein,we report PtSnBiPdIn HEA nanoparticles with tensilestrain and nanoporous structures as high-performance electrocatalysts for oxidation of ethylene glycol to CO_(2).The mass activity(MA)of the PtSnBiPdIn/C catalyst for alkaline ethylene glycol oxidation reaction(EGOR)are 29.76 A·mgPt+Pd−1,which not only substantially surpasses those of commercial Pt/C and Pd/C catalysts but also ranks among the best reported EGOR catalysts.Moreover,this catalyst also greatly enhances in electrocatalytic performance for both methanol oxidation reaction(MOR)and ethanol oxidation reaction(EOR),showcasing its versatility across a wide range of alcohol oxidation reactions.In-situ Fourier transform infrared(FTIR)spectroscopy confirms the preferential selection of the non-CO reaction pathway.Density functional theory(DFT)calculation reveals that the PtSnBiPdIn HEA nanoparticles exhibit enhanced electron transfer,superior catalytic activity,and remarkable CO poisoning resistance.展开更多
The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mat...The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mation,thus may lead to uncertainties in resource estimation.To accurately identify the'sweet-spot'intervals amongst heterogeneous lithofacies,we conducted a very high-resolution and quantitative analysis from in-situ macroscopic scale to laboratory microscopic scale on the Goldwyer formation of Canning Basin,Western Australia.The comprehensive advanced well logging and slim-compact micro imager(SCMI)technologies were synthetically applied in couple with the laboratory nanoscaled ex-periments.The results unveiled an extraordinarily large lithofacies heterogeneity between different rock intervals,with distinguished features shown in Goldwyer Ⅰ,Ⅱ,and Ⅲ members.The most favorable lithofacies is recognized as the laminated argillaceous thermally-matured organic matter(OM)-rich mudstone,which is widely developed in Goldwyer Ⅲ as the major attributor to'sweet-spot'intervals.Goldwyer Ⅱ is exclusively characterized by thick mudstone intervals(94.4%),interbedded with thin calcareous mudstones(5.5%),corresponding to a depositional environment of low-energy distal section of the outer ramp settings.Microscopically,the most favorable lithofacies in'sweet-spot'intervals develop numerous OM-/mineral nanopores for hydrocarbon storage.Illite-rich lithofacies develops abundant inter-particle pores from 2 to 17 nm that mainly contribute to pore volume for free gas storage capacity.OM-rich lithofacies with higher maturity have OM-pores with good connectivity,bearing large specific surface area that is beneficial for adsorbed gas capacity.展开更多
The fabrication of electrocatalysts with high activity and acid stability for acidic oxygen evolution reaction(OER)is an urgent need,yet extremely challenging.Here,we report the design and successful fabrication of a ...The fabrication of electrocatalysts with high activity and acid stability for acidic oxygen evolution reaction(OER)is an urgent need,yet extremely challenging.Here,we report the design and successful fabrication of a high performance self-supported cogwheel arrays-like nanoporous Ir_(x)Ru_(1−x)O_(2) catalyst with abundant atomic steps for acidic OER using a facile alloy-spinningelectrochemical activation method that allows large-scale fabrication.The obtained Ir_(x)Ru_(1−x)O_(2) catalysts merely need overpotentials of 211 and 295 mV to deliver catalytic current densities of 10 and 300 mA·cm^(−2) in 0.5 M H_(2)SO_(4),respectively,and can sustain constant OER electrolysis for at least 140 h at a high current density of 300 mA·cm^(−2).Further density functional theory(DFT)calculations uncover that such high intrinsic activities mainly originate from the largely exposed high-index atomic step planes,which markedly lower the limiting potential of the rate-determining step(RDS)of OER.These findings provide an insight into the exploration of high performance electrocatalysts,and open up an avenue for further developing the state-of-theart Ir and/or Ru-based catalysts for large-scale practical applications.展开更多
With the rapid development of two-phase heat exchangers,the further improvement of the capillary performance of their internal wick faces a great challenge.As an important technology in the surface treatment of alumin...With the rapid development of two-phase heat exchangers,the further improvement of the capillary performance of their internal wick faces a great challenge.As an important technology in the surface treatment of aluminum alloys,anodic oxidation has been widely used to develop various functional nanostructures.In this study,nanopores with diameters of 30–40 nm were fabricated on the surface of aluminum fibers through anodic oxidation under an oxalic acid system.Results showed that anodizing increased the specific surface area of the aluminum braid by 163 times,and changed its surface wettability from hydrophobic to superhydrophilic.A significant reduction in the effective capillary radius can substantially increase the capillary force of aluminum braids on the basis of capillary theory.Therefore,the nanoporous aluminum braids can be used as a novel wick in the vapor chamber to improve its capillary performance.Capillary rate-of-rise tests with ethanol and acetone were performed to characterize the capillary of this novel wick structure.Infrared thermal imaging was utilized to monitor the capillary rise of aluminum braided wicks.The capillary force of the anodized wicks was greater than that of a normal wick,and the maximum capillary rise height was 81 mm.The nanoporous aluminum braided wicks prepared by anodizing could be applied in heat transfer.展开更多
The nanopore structures in precursors Four carbon-fiber precursors are prepared. They are crucial to the performance of PAN-based carbon fibers are bath-fed filaments （A）, water-washing filaments （B） hot-stretchin...The nanopore structures in precursors Four carbon-fiber precursors are prepared. They are crucial to the performance of PAN-based carbon fibers are bath-fed filaments （A）, water-washing filaments （B） hot-stretching filaments （C） and drying-densification filaments （D）. Synchrotron radiation small angle X-ray scattering is used to probe and compare the nanopore structures of the four fibers. The nanopore size, discrete volume distribution, nanopore orientation degree along the fiber axis and the porosity are obtained. The results demonstrate that the nanopores are mainly formed in the water-washing stage. During the processes of the subsequent production technologies, the slenderness ratio of nanopores and their orientation degree along the fiber axis increase further and simultaneously, the porosity decreases. These results are helpful for improving the performance of the final carbon fibers.展开更多
In this study,a group of overmature coal-measure shale core samples was collected in situ from an exploration well located in the Wuxiang area of the Qinshui Basin,north China.The pore water contents(CPW)of the shales...In this study,a group of overmature coal-measure shale core samples was collected in situ from an exploration well located in the Wuxiang area of the Qinshui Basin,north China.The pore water contents(CPW)of the shales under as-received conditions,equilibrium water contents(CEW)of the shales under moisture equilibrium conditions(relative humidity:100%),and nanopore structures of the shales under both as-received and dried conditions were measured.The results indicate that the CPW values of these shales are much lower than their CEW values,which implies that the bulk pore systems of these shales have low water-bearing extents.In addition,approximately half of the total pore volumes and surface areas of the as-received shales are occupied by pore water,and the effects of pore water on shale nanopores with various pore types and widths are different.The average water-occupied percentages(PW)are 59.16%−81.99%and 42.53%−43.44%for the non-micropores and micropores,respectively,and are 83.54%−97.69%and 19.57%−26.42%for the inorganic-matter hosted(IM)and organic-matter hosted(OM)pores,respectively.The pore water in shales not only significantly reduces the storage of shale gas by occupying many pore spaces,but also causes the shale gas,especially the absorbed gas,to be mostly stored in the OM pores;meanwhile,the IM pores mainly store free gas.Therefore,the water-bearing characteristics and their effects on the pore structures and gas-bearing properties of coal-measure shales should be noted for the evaluation and exploration of shale gas in the Qinshui Basin.展开更多
基金supported by the National Natural Science Foundation of China (no.52175160).
文摘The acoustic performance for the nanoporous frustule of the diatom is studied based on the computational fluid dynamics theory and acoustic theory involved.Representative Coscinodiscus sp.frustule is observed through the scanning electron microscope and modeled by the commercial software Solidworks.Further,the acoustic performance for the Coscinodiscus sp.frustule is studied at the varied depth,diameter or interval of the pore,as well as the film thickness of the fluid surrounding the Coscinodiscus sp.frustule.The numerical results show that,when the upper and lower pore diameters are separately 200 and 300 nm,the upper and lower pore depths are separately 200 and 250 nm,and both the pore interval and fluid film thickness are 500 nm,the elaborate nanoporous structure of Coscinodiscus sp.frustule can lower its acoustic power level by 17.49%,compared with that without porous structure.Meanwhile,the double-layer pore of Coscinodiscus sp.frustule can decrease its acoustic power level by 12.69%,compared with its single-layer pore structures.
基金sponsored by the National Natural Science Foundation of China(Nos.5210125 and 52375422)the Science Research Project of Hebei Education Department(No.BJK2023058)the Natural Science Foundation of Hebei Province(Nos.E2020208069,B2020208083 and E202320801).
文摘The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x),in situ grown on nickel foam(NF),holds great promise as a high-efficient bifunctional electrocatalyst(named R-CoFe/Ce/NF)for water splitting.Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization.By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_(2−x) heterostructure interfaces,the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution(η_(10)=227 mV;η_(500)=450 mV)and hydrogen evolution(η_(10)=35 mV;η_(408)=560 mV)reactions with high normalized electrochemical active surface areas,respectively.Additionally,the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm^(−2) only at 1.75 V;the decline of activity is satisfactory after 100-h durability test at 300 mA·cm^(−2).Density functional theory also demonstrates that the electron can transfer from CeO_(2−x) by virtue of O atom to CoFeOOH at CoFeOOH/CeO_(2−x) heterointerfaces and enhancing the adsorption of reactant,thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting.
基金supported by the National Natural Science Foundation of China(No.52101251)the Science Research Project of Hebei Education Department(No.BJK2023058)the Natural Science Foundation of Hebei Province(Nos.E2020208069 and B2020208083).
文摘Retaining satisfactory electrocatalytic performance under high current density plays a crucial role in industrial water splitting but is still limited to the enormous energy loss because of insufficient exposure of active sites caused by the blocked mass/charge transportation at this condition.Herein,we present a freestanding lamellar nanoporous Ni-Co-Mn alloy electrode(Lnp-NCM)designed by a refined variant of the“dealloying-coarsening-dealloying”protocol for highly efficient bifunctional electrocatalyst,where large porous channels distribute on the surface and small porous channels at the interlayer.With its 3D lamellar architecture regulating,the electrocatalytic properties of the electrodes with different distances between lamellas are compared,and faster energy conversion kinetics is achieved with efficient bubble transport channels and abundant electroactive sites.Note that the optimized sample(Lnp-NCM4)is expected to be a potential bifunctional electrocatalyst with low overpotentials of 258 and 439 mV at high current densities of 1000 and 900 mA·cm^(-2)for hydrogen and oxygen evolution reactions(HER and OER),respectively.During overall water splitting in a two-electrode cell with Lnp-NCM4 as cathode and anode,it only needs an ultralow cell voltage of 1.75 V to produce 100 mA·cm^(-2)with remarkable long-term stability over 50 h.This study on lamellar nanoporous electrode design approaches industrial water splitting requirements and paves a way for developing other catalytic systems.
基金Project(51371104)supported by the National Natural Science Foundation of China
文摘The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature chemical corrosion, low and high current level electrochemical corrosion, four types of porous structures, including uneven corrosion pits, hybrid porous, haystack type and bicontinuous model were prepared by chemically and electrochemically dealloying the porous Cu-34.6%Mn alloy made by the Gasar process. Then, the surface diffusion coefficient(DS) and the diffusion frequency(kD) of Cu atom, as well as the dissolution frequency(kE) of Mn atom were calculated with dealloying condition. The dealloyed morphologies for room temperature chemical corrosion and low current level electrochemical corrosion were similar due to the same DS. While the dealloyed structures changed from bulk hybrid porous structure to bicontinuous porous film with decreasing kD/kE.
基金Financial supports from Australian Research Council through Discovery Project(DP130103592)National Natural Science Foundation of China(Grant No.51771103)。
文摘Although an increasing interest has been attracted to further develop heterostructured catalysts from metallic glasses(MGs) by heat treatment, overcoming surface oxidation effect is still a critical problem for such environmental catalysts. Herein, a short-time electrochemical etching of partially crystallized Febased ribbons in 0.3 M H3 PO4 electrolyte enables the formation of honeycomb-like nanoporous structure as effective catalytic active sites in Fenton-like process. Studies of structure and surface morphologies reveal that the formation of nanoporous structure by potentiostatic etching originates from electrochemical potential difference of nanocrystals(a-Fe(Si) and Fe2 B) and residual amorphous phase in partially crystallized ribbons, where Fe2 B having a lower open circuit potential tends to be selectively dissolved.Simultaneously, thin oxide layer after electrochemical etching exposes more active sites for H2 O2 activation and provides an effective protection of nanocrystals from massive loss during etching. Investigation of optimal processing conditions suggests that the selection of electrolyte plays an important role;dye degradation rates of etched ribbons in HNO3 and Na2 SO4 electrolytes can also achieve at least 2 times higher than that of as-annealed ribbons. This work holds the promise to develop novel environmental catalysts by effective electrochemical etching of partially crystallized ribbons.
基金the financial supports from State Key Laboratory of Light Alloy Casting Technology for High-end Equipmentthe Natural Science Foundation of Liaoning Province,China(No.2020-KF-14-03)the National Natural Science Foundation of China(No.51775353)。
文摘Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.
基金the financial support of the National Science and Technology Major Project(No.2016ZX05034-001)National Natural Science Foundation of China(No.41472112)
文摘The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller （BET）, Dubinin-Radushkevich （DR）, t-plot, Barrett- Joyner-Halenda （BJH） and density functional theory （DFT） methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that （1） The Lower Silurian shale has high TOC content of 0.92%~96%, high quartz content of 30.6%-69.5%, and high clays content of 24.1%-51.2%. The total specific surface area varies from 7.56 m^2/g to 25.86 m^2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. （2） Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. （3） A combination of N2 and CO2 adsorption provides the most suitable detection range （~0.3-60 nm） and has high reliability and accuracy for nanopore structure characterization. （4） The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.
基金This study was financially supported by the National Natural Science Foundation of China(No.51771132).
文摘High entropy alloys(HEAs)containing five or more equimolar components have shown promising catalytic performance due to their unique chemical and mechanical properties.However,it is still challenging to prepare scalable and efficient nanoporous HEAs as catalysts.Here,we present a facile strategy to synthesize largescale nanoporous HEAs particles by combing vacuum induction melting,gas atomization,and acidic etching procedure.The application of HEAs to energy conversion is evaluated with electrocatalytic oxygen evolution reaction(OER)on AlCrCuFeNi HEAs.The HEAs exhibit a low OER overpotential of 270 mV to achieve a current density of 10 mA·cm^(-2),a small Tafel slope of 77.5 mV·dec^(-1),and long-term stability for over 35 h in 1 mol·L^(-1) KOH,which is comparable to the state-of-the-art OER electrocatalyst RuO2.The findings in this paper not only provide an industrial approach to produce nanoporous HEAs powder but also inspire the applications of HEAs as catalysts.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(Grant Nos.2022R1A2C3009087 and 2022R1F1A1073173)the Korean Institute of Energy Technology Evaluation and Planning (KETEP)+1 种基金the Ministry of Trade,Industry & Energy (MOTIE) of the Republic of Korea (Grant No. RS-2024-00394769)the research grant of Kongju National University in 2022
文摘The frost-driven self-fracture of ionomer-bound carbon electrodes compromises the mechanical stability of electrochemical systems under subzero conditions.This study suggests that the mechanical degradation of ionomer-bound carbon electrodes under subfreezing conditions is primarily driven by damage within the ionomer binder phase rather than within the nanopores.This damage occurs owing to the expansion of confined water upon freezing.Reducing the size of the freezable water domains significantly enhances the mechanical robustness.Structural and mechanical analyses reveal that thermal reconfiguration effectively modifies the ionomer nanostructure,leading to an approximately 30%reduction in water uptake and improved resistance to frost-induced self-fracturing.Nanostructural analyses further confirm that crystallized packing in the ionomer binder minimizes the number of water retention sites,thereby restricting the buildup of internal stress during freezing.Consequently,the elongation of the as-prepared electrodes reduces by approximately 65%after freezing at−10℃,whereas that of the thermally reconfigured electrodes is above 90%of its initial value with minimal deterioration.These findings highlight the critical role of ionomer-phase engineering in improving the low-temperature durability of ionomer-bound carbon electrodes,providing a scalable strategy applicable to fuel cells,water electrolyzers,and next-generation energy storage systems without requiring antifreezing agents.
基金supported by National Natural Science Foundation of China–Research Grants Council Joint Research Fund Joint Research Scheme(Grant No.N_HKU159/22)the National Natural Science Foundation of China(Grant No.12172260)+3 种基金the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant No.RFS2021-1S05)the Key Research and Development Program of Hubei Province(Grant No.2021BAA192)the Fundamental Research Funds for the Central Universities(Grant No.2042023kf0233)the Materials Innovation Institutefor Life Sciences and Energy(MILES),University of Hong Kong Shenzhen Institute of Research and Innovation(Grant No.SIRI/04/04/2023/01/F09)。
文摘Nanoporous metamaterials have garnered significant attention due to their unique combination of lightweight,high specific-surface-area,and small size effects.However,their mechanical performance is usually limited by structural imperfections introduced during conventional fabrication processes.In this study,we present a universal and cost-effective thermomechanical molding technique for directly fabricating three-dimensional(3D)crystalline metamaterials.Micropillar compression tests show that the nanoporous structures fabricated through this technique exhibit significantly enhanced mechanical properties,even with a yield strength 2 times higher than that of the corresponding bulk materials.Transmission electron microscope(TEM)characterization revealed the single-crystalline nature of the whole nanoporous structure,which can fully utilize the size effect of strength,that is,“the smaller the stronger”,thereby offsetting the reduction of effective load-bearing materials caused by porosity.Moreover,we demonstrate that the thermomechanical molding technique is highly versatile,enabling the fabrication of 3D nanoporous structures in a wide range of elemental metals,thermoelectric,semiconductor,and phase-change materials,offering a promising way for the development of next-generation functional nanoporous metamaterials.
基金the financial support for the Australian Research Council(FT110100341 and DP140102624)
文摘The high electrical conductivity and high specific surface area of graphene are traditionally regarded as the most intriguing features for its promise as the electrode material for supercapacitors. In this perspective, we highlight that from the engineering point of view, the unique colloidal chemistry of chemically functionalized graphene is the key property that has made graphene stand out as a promising nanoscale building block for constructing unique nanoporous electrodes for capacitive energy storage, We present several examples to demonstrate bow the non-covalent colloidal forces between graphene sheets can be harnessed to engineer the nanostructure of graphene-based bulk electrodes for supercapacitors based on both the electrical double layer storage and the redox reaction or pseudo-capacitance mechanisms. The colloidal engineering strategy can be extended to enable other nanomaterials to achieve high energy storage performance.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.52101233,51931007,and 52071279)the Hebei Natural Science Foundation(No.E2022203010)the Innovation Capability Improvement Project of Hebei Province(No.22567605H).
文摘The enhancement of near-field radiative heat transfer(NFRHT)has now become one of the research hotspots in the fieldsof thermal management and imaging due to its ability to improve the performance of near-field thermoelectric devices and near-field imaging systems.In this paper,we design three structures(multilayer structure,nanoporous structure,and nanorod structure)based on high-entropy alloys to realize the enhancement of NFRHT.By combining stochastic electrodynamicsand Maxwell-Garnett's description of the effective medium,we calculate the radiative heat transfer under different parametersand find that the nanoporousstructure has the largest enhancement effect on NFRHT.The near-field heat transfer factor(q)of this structure(q=1.40×10^(9)W/(m^(2)·K))is three times higher than that of the planestructure(q=4.6×10^(8)W/(m^(2)·K)),and about two orders of magnitude higher than that of the SiO2plate.Thisresult providesa freshidea for the enhancement of NFRHT and will promote the application of high-entropy alloy materials in near-field heat radiation.
基金funding from the National Natural Science Foundation of China(Nos.12475323 and U21A20317)the Natural Science Research Project of Universities in Anhui Province(Nos.2022AH050112 and 2024AH050082)+3 种基金the Project of Anhui Provincial Department of Education(No.2022AH010004)the Fund of Key Laboratory of Advanced Materials of Ministry of Education No(Advmat-2401)the Natural Science Foundation of Anhui Province(No.2108085MB55)the Fund of Development of High-Resolution X-ray Fluorescence Analyzer.
文摘High entropy alloys(HEAs)have garnered significant attention due to their distinctive properties,while their precise regulation remains at infancy stage.Herein,we report PtSnBiPdIn HEA nanoparticles with tensilestrain and nanoporous structures as high-performance electrocatalysts for oxidation of ethylene glycol to CO_(2).The mass activity(MA)of the PtSnBiPdIn/C catalyst for alkaline ethylene glycol oxidation reaction(EGOR)are 29.76 A·mgPt+Pd−1,which not only substantially surpasses those of commercial Pt/C and Pd/C catalysts but also ranks among the best reported EGOR catalysts.Moreover,this catalyst also greatly enhances in electrocatalytic performance for both methanol oxidation reaction(MOR)and ethanol oxidation reaction(EOR),showcasing its versatility across a wide range of alcohol oxidation reactions.In-situ Fourier transform infrared(FTIR)spectroscopy confirms the preferential selection of the non-CO reaction pathway.Density functional theory(DFT)calculation reveals that the PtSnBiPdIn HEA nanoparticles exhibit enhanced electron transfer,superior catalytic activity,and remarkable CO poisoning resistance.
基金Fundamental Research Programme of Yunnan Province(202201AU070041)the funding of Yunnan University Young Talent Programme(CZ21623201)+2 种基金the funding of State Key Laboratory of Coal Mine Disaster Dynamics and Control in Chongqing University(2011DA105287-FW202106)the funding from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,under the Institute of Geology in Chinese Academy of Geological Sciences,Beijing(J1901)Much gratitudes for the Department of Mines,Industry Regulation and Safety under the Government of Western Australia for granting us the core samples under Approval Nos.G32825&N00413。
文摘The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mation,thus may lead to uncertainties in resource estimation.To accurately identify the'sweet-spot'intervals amongst heterogeneous lithofacies,we conducted a very high-resolution and quantitative analysis from in-situ macroscopic scale to laboratory microscopic scale on the Goldwyer formation of Canning Basin,Western Australia.The comprehensive advanced well logging and slim-compact micro imager(SCMI)technologies were synthetically applied in couple with the laboratory nanoscaled ex-periments.The results unveiled an extraordinarily large lithofacies heterogeneity between different rock intervals,with distinguished features shown in Goldwyer Ⅰ,Ⅱ,and Ⅲ members.The most favorable lithofacies is recognized as the laminated argillaceous thermally-matured organic matter(OM)-rich mudstone,which is widely developed in Goldwyer Ⅲ as the major attributor to'sweet-spot'intervals.Goldwyer Ⅱ is exclusively characterized by thick mudstone intervals(94.4%),interbedded with thin calcareous mudstones(5.5%),corresponding to a depositional environment of low-energy distal section of the outer ramp settings.Microscopically,the most favorable lithofacies in'sweet-spot'intervals develop numerous OM-/mineral nanopores for hydrocarbon storage.Illite-rich lithofacies develops abundant inter-particle pores from 2 to 17 nm that mainly contribute to pore volume for free gas storage capacity.OM-rich lithofacies with higher maturity have OM-pores with good connectivity,bearing large specific surface area that is beneficial for adsorbed gas capacity.
基金supported by the S&T Partnership and International S&T Cooperation Program of Shanghai Cooperation Organization(No.2020E01040)the High-level Talent Project of Xinjiang Uygur Autonomous Region(No.2020000039)+3 种基金the National Key R&D Program of China(Nos.2018YFB0104400 and 2016YFB0100100)the National Natural Science Foundation of China(Nos.62104073,21825202,92045302,21972055,and 21733012)Newton Advanced Fellowships(No.NAF/R2/180603)B.L.acknowledges the support by the National Natural Science Foundation of China(No.21573255).
文摘The fabrication of electrocatalysts with high activity and acid stability for acidic oxygen evolution reaction(OER)is an urgent need,yet extremely challenging.Here,we report the design and successful fabrication of a high performance self-supported cogwheel arrays-like nanoporous Ir_(x)Ru_(1−x)O_(2) catalyst with abundant atomic steps for acidic OER using a facile alloy-spinningelectrochemical activation method that allows large-scale fabrication.The obtained Ir_(x)Ru_(1−x)O_(2) catalysts merely need overpotentials of 211 and 295 mV to deliver catalytic current densities of 10 and 300 mA·cm^(−2) in 0.5 M H_(2)SO_(4),respectively,and can sustain constant OER electrolysis for at least 140 h at a high current density of 300 mA·cm^(−2).Further density functional theory(DFT)calculations uncover that such high intrinsic activities mainly originate from the largely exposed high-index atomic step planes,which markedly lower the limiting potential of the rate-determining step(RDS)of OER.These findings provide an insight into the exploration of high performance electrocatalysts,and open up an avenue for further developing the state-of-theart Ir and/or Ru-based catalysts for large-scale practical applications.
基金the Natural Science Foundation of Guangdong Province,China(No.2021B1515020087)the National Natural Science Foundation of China(No.51775197).
文摘With the rapid development of two-phase heat exchangers,the further improvement of the capillary performance of their internal wick faces a great challenge.As an important technology in the surface treatment of aluminum alloys,anodic oxidation has been widely used to develop various functional nanostructures.In this study,nanopores with diameters of 30–40 nm were fabricated on the surface of aluminum fibers through anodic oxidation under an oxalic acid system.Results showed that anodizing increased the specific surface area of the aluminum braid by 163 times,and changed its surface wettability from hydrophobic to superhydrophilic.A significant reduction in the effective capillary radius can substantially increase the capillary force of aluminum braids on the basis of capillary theory.Therefore,the nanoporous aluminum braids can be used as a novel wick in the vapor chamber to improve its capillary performance.Capillary rate-of-rise tests with ethanol and acetone were performed to characterize the capillary of this novel wick structure.Infrared thermal imaging was utilized to monitor the capillary rise of aluminum braided wicks.The capillary force of the anodized wicks was greater than that of a normal wick,and the maximum capillary rise height was 81 mm.The nanoporous aluminum braided wicks prepared by anodizing could be applied in heat transfer.
基金Supported by National Natural Science Foundation of China (10835008)Knowledge Innovation Program of Chinese Academy of Sciences (KJCX3-SYW-N8)Momentous Equipment Program of Chinese Academy of Sciences (YZ200829)
文摘The nanopore structures in precursors Four carbon-fiber precursors are prepared. They are crucial to the performance of PAN-based carbon fibers are bath-fed filaments （A）, water-washing filaments （B） hot-stretching filaments （C） and drying-densification filaments （D）. Synchrotron radiation small angle X-ray scattering is used to probe and compare the nanopore structures of the four fibers. The nanopore size, discrete volume distribution, nanopore orientation degree along the fiber axis and the porosity are obtained. The results demonstrate that the nanopores are mainly formed in the water-washing stage. During the processes of the subsequent production technologies, the slenderness ratio of nanopores and their orientation degree along the fiber axis increase further and simultaneously, the porosity decreases. These results are helpful for improving the performance of the final carbon fibers.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.U1810201 and 41925014)the Natural Science Foundation of Guangdong Province(No.2021A1515011381).
文摘In this study,a group of overmature coal-measure shale core samples was collected in situ from an exploration well located in the Wuxiang area of the Qinshui Basin,north China.The pore water contents(CPW)of the shales under as-received conditions,equilibrium water contents(CEW)of the shales under moisture equilibrium conditions(relative humidity:100%),and nanopore structures of the shales under both as-received and dried conditions were measured.The results indicate that the CPW values of these shales are much lower than their CEW values,which implies that the bulk pore systems of these shales have low water-bearing extents.In addition,approximately half of the total pore volumes and surface areas of the as-received shales are occupied by pore water,and the effects of pore water on shale nanopores with various pore types and widths are different.The average water-occupied percentages(PW)are 59.16%−81.99%and 42.53%−43.44%for the non-micropores and micropores,respectively,and are 83.54%−97.69%and 19.57%−26.42%for the inorganic-matter hosted(IM)and organic-matter hosted(OM)pores,respectively.The pore water in shales not only significantly reduces the storage of shale gas by occupying many pore spaces,but also causes the shale gas,especially the absorbed gas,to be mostly stored in the OM pores;meanwhile,the IM pores mainly store free gas.Therefore,the water-bearing characteristics and their effects on the pore structures and gas-bearing properties of coal-measure shales should be noted for the evaluation and exploration of shale gas in the Qinshui Basin.
