Porous framework materials for energy&environment relevant applications:A systematic review

Carbon peaking and carbon neutralization trigger a technical revolution in energy&environment related fields.Development of new technologies for green energy production and storage,industrial energy saving and efficiency reinforcement,carbon capture,and pollutant gas treatment is in highly imperious demand.The emerging porous framework materials such as metal–organic frameworks(MOFs),covalent organic frameworks(COFs)and hydrogen-bonded organic frameworks(HOFs),owing to the permanent porosity,tremendous specific surface area,designable structure and customizable functionality,have shown great potential in major energy-consuming industrial processes,including sustainable energy gas catalytic conversion,energy-efficient industrial gas separation and storage.Herein,this manuscript presents a systematic review of porous framework materials for global and comprehensive energy&environment related applications,from a macroscopic and application perspective.

Integrating Levels of Hierarchical Organization in Porous Organic Molecular Materials

Porous organic molecular materials(POMMs)are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks,mainly held by non-covalent interactions.POMMs represent a variety of chemical families,such as hydrogen-bonded organic frameworks,porous organic salts,porous organic cages,C-H···πmicroporous crystals,supramolecular organic frameworks,π-organic frameworks,halogen-bonded organic framework,and intrinsically porous molecular materials.In some porous materials such as zeolites and metal organic frameworks,the integration of multiscale has been adopted to build materials with multifunctionality and optimized properties.Therefore,considering the significant role of hierarchy in porous materials and the growing importance of POMMs in the realm of synthetic porous materials,we consider it appropriate to dedicate for the first time a critical review covering both topics.Herein,we will provide a summary of literature examples showcasing hierarchical POMMs,with a focus on their main synthetic approaches,applications,and the advantages brought forth by introducing hierarchy.

Capillary Property of Entangled Porous Metallic Wire materials and Its Application in Fluid Buffers:Theoretical Analysis and Experimental Study

Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).

Effect of Zircon Addition on Properties of Corundum Porous Materials

This paper aims to improve the corrosion resistance of dispersive purging plugs.White fused corundum particles and fine powder,α-Al_(2)O_(3) micropowder,Cr_(2)O_(3) micropowder,Guangxi clay and zircon powder were used as the main raw materials.The mass ratio of white fused corundum particles and fine powder was fixed at 85:15,and 0,1%,2%,or 3%(by mass)of zircon fine powder was added to replace the same amount of white fused corundum fine powder.The corundum porous material was prepared by the particle stacking pore-forming method at 1650℃for 3 h.The effect of the zircon addition on the properties and microstructure of porous materials was investigated.The results show that:after adding zircon,the permeability of the porous material increases,the cold and hot strengths increase obviously,and the expansion rate after firing decreases.When the addition of zircon is 2%,the comprehensive performance of the specimen is optimal with the smallest linear change rate and the highest permeability.

Sintering preparation of porous sound-absorbing materials from steel slag

Porous sound-absorbing materials were prepared from steel slag using waste expanded polystyrene（EPS） particles as pore former.The influences of the experimental conditions such as fly ash content,sintering temperature,sintering time,and pore former addition on the performance of the porous sound-absorbing materials were investigated.The results show that the porosity of the specimens can reach above 50.0%;the compressive strength and average sound-adsorption coefficient of the sintered specimens are above 3.0 MPa and 0.47,respectively.The optimum preparation conditions for the steel slag porous sound-absorbing materials are as follows：mass fraction of fly ash 50%,waste EPS particles 3.6 g,sintering temperature 1100℃,and sintering time 7.5h,which are determined by considering the properties of the sound-absorbing materials,energy consumption and cost.

Fractal dimension for porous metal materials of FeCrAl fiber

The FeCrA1 fiber was used to prepare porous metal materials with air-laid technology, and then followed by sintering at 1300 ℃ for a holding period of 2 h in the vacuum. In addition, a novel fractal soft, which was developed based on the fractal theory and the computer image processing technology, was explored to describe the pore structure of porous metal materials. Furthermore, the fractal dimension of pore structure was calculated by the soft and the effects of magnification and porosity on ffactal dimension were also discussed. The results show that the fractal dimension decreases with increase in the magnification, while it increases continuously with the porosity enhancing. The interrelationship between the fractal dimension and the magnification or porosity can be presented by the equation of D=α_0exp（-x/α_1）＋α_2和D=k_2-（k_1-k_2）/[1＋exp（（θ-k_0）/k_3）], respectively.

A Model for Mechanical Property Evaluation of the Periodic Porous Low-k Materials by SAW

The influence of the distribution of nano-pores on the mechanical properties evaluation of porous low-k films by surface acoustic waves （SAW） is studied. A theoretical SAW propagation model is set up to characterize the periodic porous dielectrics by transversely isotropic symmetry. The theoretical deductions of SAW propagating in the low-k film/Si substrate layered structure are given in detail. The dispersive characteristics of SAW in differ- ent propagation directions and the effects of the Young＇s moduli E, E′ and shear modulus G′ of the films on these dispersive curves are found. Computational results show that E′ and G′ cannot be measured along the propagation direction that is perpendicular to the nano-pores＇ direction.

Volumetric extraction of porous materials based on octree algorithm

Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree nodes is depicted in details,which is involved in six steps of the volume growth model and one step of the volume decomposition model.Moreover,the conditions of both the proceeding traversal and three possibilities of terminating are given,and the traversal algorithm of completeness is proved from a theoretical perspective.Finally,using a simulated volumetric dataset of columnar pores,the extracting effectiveness of the octree traversal algorithm is verified.The results show that the volume and the distribution information of pores can be successfully extracted by the proposed algorithm,which builds a solid foundation for a more effective performance analysis of porous materials.

Synthesis of porous nano/micro structured LiFePO_4/C cathode materials for lithium-ion batteries by spray-drying method

In order to enhance electrochemical properties of LiFePO4 （LFP） cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The results show that the spherical precursors with the sizes of 0.5-5 μm can be completely converted to LFP/C when the calcination temperature is higher than 500 ℃. The LFP/C microspheres obtained at calcination temperature of 700 ℃ are composed of numerous particles with sizes of -20 nm, and have well-developed interconnected pore structure and large specific surface area of 28.77 mE/g. The specific discharge capacities of the LFP/C obtained at 700 ℃ are 162.43, 154.35 and 144.03 mA.h/g at 0.5C, 1C and 2C, respectively. Meanwhile, the capacity retentions can reach up to 100% after 50 cycles. The improved electrochemical properties of the materials are ascribed to a small Li＋ diffusion resistance and special structure of LFP/C microspheres.

Multi-Material Topology Optimization for Spatial-Varying Porous Structures

This paper aims to propose a topology optimization method on generating porous structures comprising multiple materials.The mathematical optimization formulation is established under the constraints of individual volume fraction of constituent phase or total mass,as well as the local volume fraction of all phases.The original optimization problem with numerous constraints is converted into a box-constrained optimization problem by incorporating all constraints to the augmented Lagrangian function,avoiding the parameter dependence in the conventional aggregation process.Furthermore,the local volume percentage can be precisely satisfied.The effects including the globalmass bound,the influence radius and local volume percentage on final designs are exploited through numerical examples.The numerical results also reveal that porous structures keep a balance between the bulk design and periodic design in terms of the resulting compliance.All results,including those for irregular structures andmultiple volume fraction constraints,demonstrate that the proposedmethod can provide an efficient solution for multiple material infill structures.

Biomass-derived porous carbon materials for advanced lithium sulfur batteries

Biomass, as the most widely used carbon sources, is the main ingredient in the formation of fossil fuels. Biomass-derived novel carbons(BDNCs) have attracted much attention because of its adjustable physical/chemical properties, environmentally friendliness, and considerable economic value. Nature contributes to the biomass with bizarre microstructures with micropores, mesopores or hierarchical pores.Currently, it has been confirmed that biomass has great potential applications in energy storage devices,especially in lithium-sulfur(Li–S) batteries. In this article, the synthesis and function of BDNCs for Li–S batteries are presented, and the electrochemical effects of structural diversity, porosity and surface heteroatom doping of the carbons in Li-S batteries are discussed. In addition, the economic benefits, new trends and challenges are also proposed for further design excellent BDNCs for Li–S batteries.

Review of the fabrication and application of porous materials from silicon-rich industrial solid waste

Porous materials have promise as sound insulation, heat barrier, vibration attenuation, and catalysts. Most industrial solid wastes, such as tailings, coal gangue, and fly ash are rich in silicon. Additionally, a high silicon content waste is a potential raw material for the syn- thesis of silicon-based, multi-porous materials such as zeolites, mesoporous silica, glass-ceramics, and geopolymer foams. Representative sil- icon-rich industrial solid wastes (SRISWs) are the focus of this mini review of the processing and application of porous silicon materials with respect to the physical and chemical properties of the SRISW. The transformation methods of preparing porous materials from SRISWs are summarized, and their research status in micro-, meso-, and macro-scale porous materials are described. Possible problems in the application of SRISWs and in the preparation of functional porous materials are analyzed, and their development prospects are discussed. This review should provide a typical reference for the recycling and use of industrial solid wastes to develop sustainable “green materials.”

A Review on Metal-Organic Framework-Derived Porous Carbon-Based Novel Microwave Absorption Materials

The development of microwave absorption materials(MAMs) is a considerable important topic because our living space is crowed with electromagnetic wave which threatens human’s health.And MAMs are also used in radar stealth for protecting the weapons from being detected.Many nanomaterials were studied as MAMs,but not all of them have the satisfactory performance.Recently,metal-organic frameworks(MOFs) have attracted tremendous attention owing to their tunable chemical structures,diverse properties,large specific surface area and uniform pore distribution.MOF can transform to porous carbon(PC) which is decorated with metal species at appropriate pyrolysis temperature.However,the loss mechanism of pure MOF-derived PC is often relatively simple.In order to further improve the MA performance,the MOFs coupled with other loss materials are a widely studied method.In this review,we summarize the theories of MA,the progress of different MOF-derived PC-based MAMs,tunable chemical structures incorporated with dielectric loss or magnetic loss materials.The different MA performance and mechanisms are discussed in detail.Finally,the shortcomings,challenges and perspectives of MOF-derived PC-based MAMs are also presented.We hope this review could provide a new insight to design and fabricate MOF-derived PC-based MAMs with better fundamental understanding and practical application.

Functional porous carbon-based composite electrode materials for lithium secondary batteries

The synthetic routes of porous carbons and the applications of the functional porous carbon-based composite electrode materials for lithium secondary batteries are reviewed. The synthetic methods have made great breakthroughs to control the pore size and volume, wall thickness, surface area, and connectivity of porous carbons, which result in the development of functional porous carbon-based composite electrode materials. The effects of porous carbons on the electrochemical properties are further discussed. The porous carbons as ideal matrixes to incorporate active materials make a great improvement on the electrochemical properties because of high surface area and pore volume, excellent electronic conductivity, and strong adsorption capacity. Large numbers of the composite electrode materials have been used for the devices of electrochemical energy conversion and storage, such as lithium-ion batteries （LIBs）, Li-S batteries, and Li-O2 batteries. It is believed that functional porous carbon-based composite electrode materials will continuously contribute to the field of lithium secondary batteries.

Influence of porogen type and copper powder morphology on property of sintering copper porous materials

Copper porous materials have been manufactured by the method of powder metallurgy.Electrolytic copper powders and atomized copper powders are used as matrix material.Methylcellulose and paraffin are used as porogen.The influence of porogen type and copper powder morphology on the property of copper porous materials is investigated as well.The results show that copper porous materials with paraffin as porogen have lower porosity and permeability compared with materials using methylcellulose as porogen,due to the different pore-forming mechanisms.The pore forming mechanism of methylcellulose is thermal decomposition,while the pore forming mechanism of paraffin is melting–evaporation.The morphology of copper powders affects the contact state between adjacent powders,which further influence the sintering shrinkage.The porous materials using arborescent copper powders as matrix have lower porosity,smaller pore size and lower permeability,compared with materials with atomized copper powders as matrix.

High specific surface area porous graphene grids carbon as anode materials for sodium ion batteries

Although great accomplishments of functional material synthesis have been achieved in sodium ion batteries(SIBs)recently,there are still numerous challenges and problems in preparing carbon-based materials with porous architectures and enough lattice distance for Na^+insertion.Herein we report a templated strategy to synthesize 3D porous graphene girds(PGGs)consisting of several stacking graphene structure with ultrahigh surface area and hierarchical connected structure by employing Ag nanoparticles(NPs).The Ag NPs will regenerate for decreasing the experimental cost,also in line with principles of green chemistry and environmentally friendly strategy.The PGGs obtain advanced specific capacity of160 m A h g^(-1)at current density of 50 m A h g^(-1).Moreover,112 mA h g^(-1)capacity can be gained at 1 A h g^(-1)during 1000 cycles.Due to their porous architecture,ultrahigh surface area and low amorphous graphited structure,PGGs electrode showed the excellent electrochemical performance in high rate capability.

A thermodynamics-based three-scale constitutive model for partially saturated granular materials

A three-scale constitutive model for unsaturated granular materials based on thermodynamic theory is presented.The three-scale yield locus,derived from the explicit yield criterion for solid matrix,is developed from a series of discrete interparticle contact planes.The three-scale yield locus is sensitive to porosity changes;therefore,it is reinterpreted as a corresponding constitutive model without phenomenological parameters.Furthermore,a water retention curve is proposed based on special pore morphology and experimental observations.The features of the partially saturated granular materials are well captured by the model.Under wetting and isotropic compression,volumetric compaction occurs,and the degree of saturation increases.Moreover,the higher the matric suction,the greater the strength,and the smaller the volumetric compaction.Compared with the phenomenological Barcelona basic model,the proposed three-scale constitutive model has fewer parameters;virtually all parameters have clear physical meanings.

Model of homogenisation for analysing the effect of micrometre pore sizes on the elastic moduli of porous materials

A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed.In the proposed model,the engineering coefficients of localization of total strains(LTS coefficients)are considered instead of the classical strain localization tensors.For a pore,these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous body.To estimate the elastic moduli of a material with an arbitrary pore size,it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore size.Then,in Eshelby's model of equivalent inclusion,a transition to LTS coefficient for material with arbitrary pore size is achieved,and its elasticity moduli are determined.The results for Young's modulus of porous titanium,with different sizes of spherical pores,completely conform with the experimental data.We have obtained a model theoretic estimate of the upper bounds of Young's modulus of porous materials with infinitely small pore size.For the spherical pores,the proposed assessment coincides with the upper limits of the Hashin-Shtrikman bounds.

Review on porous nanomaterials for adsorption and photocatalytic conversion of CO_2

Photocatalytic conversion of“greenhouse gas”CO2is considered to be one of the most effective ways to alleviate current energy and environmental problems without additional energy consumption and pollutant emission.The performance of many traditional semiconductor photocatalysts is not efficient enough to satisfy the requirements of practical applications because of their limited specific surface area and low CO2adsorption capacity.Therefore,the exploration of photocatalysts with high CO2uptake is significant in the field of CO2conversion.Recently the porous materials appeared to be a kind of superior candidate for enriching the CO2molecules on the surface of photocatalysts for catalytic conversion.This paper first summarizes the advances in the development of nanoporous adsorbents for CO2capture.Three main classes of porous materials are considered:inorganic porous materials,metal organic frameworks,and microporous organic polymers.Based on systematic research on CO2uptake,we then highlight the recent progress in these porous‐material‐based photocatalysts for CO2conversion.Benefiting from the improved CO2uptake capacity,the porous‐material‐based photocatalysts exhibited remarkably enhanced efficiency in the reduction of CO2to chemical fuels,such as CO,CH4,and CH3OH.Based on reported recent achievements,we predict a trend of development in multifunctional materials with both high adsorption capability and photocatalytic performance for CO2utilization.

SIMULATION OF CYLINDRICAL UPSETTING OF POROUS MATERIALS BY FINITE ELEMENT METHOD

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