Porous Structure Design Research Articles

Advances in Porous Structure Design for Enhanced Piezoelectric and Triboelectric Nanogenerators: A Comprehensive Review

AbstractPorous structures offer several key advantages in energy harvesting, making them highly effective for enhancing the performance of piezoelectric and triboelectric nanogenerators (PENG and TENG). Their high surface area‐to‐volume ratio improves charge accumulation and electrostatic induction, which are critical for efficient energy conversion. Additionally, their lightweight and flexible nature allows for easy integration into wearable and flexible electronics. These combined properties make porous materials a powerful solution for addressing the efficiency limitations that have traditionally restricted nanogenerators. Recognizing these benefits, this review focuses on the essential role that porous materials play in advancing PENG and TENG technologies. It examines a wide range of porous materials, including aerogels, nano‐porous films, sponges, and 2D materials, explaining how their unique structures contribute to higher energy harvesting efficiency. The review also explores recent breakthroughs in the development of these materials, demonstrating how they overcome performance challenges and open up new possibilities for practical applications. These advancements position porous nanogenerators as strong candidates for use in wearable electronics, smart textiles, and Internet of Things (IoT) devices. By exploring these innovations, the review underscores the importance of porous structures in driving the future of energy harvesting technologies.

Porous Carbon‐Supported Catalysts for Proton Exchange Membrane Fuel Cells

AbstractProton exchange membrane fuel cells (PEMFCs) are crucial for the efficient utilization of hydrogen. Currently, their efficiency is mainly limited by the slow kinetics of the cathode oxygen reduction reaction (ORR) and the poisoning effect between ionomers and catalytic sites, particularly with Pt‐based catalysts. Recent works suggest that the emerging porous carbon‐supported catalysts hold promise in mitigating these challenges by ensuring fast kinetics while alleviating the poisoning. This review examines porous carbon‐supported catalysts for PEMFC cathodes, covering synthesis methods, structure and performance evaluation, and future prospects, with an emphasis on the influence of porous carbon support on PEMFC performance. On one hand, the rational design of pore structure in carbon support can help optimize the location of the active sites and enhance mass transfer. On the other hand, diverse pore structures provide a platform for gaining a deeper understanding of the mechanisms behind microscale mass transfer and reaction at the three‐phase boundaries. This review aims to inspire innovative strategies for the precise synthesis of porous carbon‐supported catalysts with various pore structures to further boost PEMFC performance.

Fabrication of core-shell Fe4N@C with sea-island structure by one-step nitriding method as efficient electromagnetic wave composite absorber

Porous structure design and magnetic-dielectric composite are effective ways to develop electromagnetic wave (EMW) absorbing materials with light-weight, thin-thickness, large effective absorption bandwidth (EAB), and strong reflection loss (RL). This article presents a simple one-step nitridation method for synthesizing Fe4N@C compounds with sea-island like and core-shell structures. The optimal RL value of Fe4N@C is up to −60.01 dB, and the EAB (frequency range for RL< −10 dB) is 5 GHz (11.1–16.1 GHz) with a thickness of 1.9 mm. The EAB reaches 5.5 GHz (12.5–18 GHz) when the matching thickness is 1.7 mm. The multi-component design achieved excellent impedance matching properties. The carbon frame connects the core-shell particles to form a three-dimensional porous structure, providing multiple reflection losses. Therefore, this work provides a convenient way to design efficient and lightweight EMW absorbers with special structures.

Co-crosslinking and anchoring strategy: One-step preparation of N-doped porous carbon for supercapacitors and zinc ion hybrid capacitors

Porous carbon has been widely used in aqueous capacitors due to its wide source, high stability, and controllable preparation. However, the two-step preparation strategy of carbonization and activation with complex operation and serious energy consumption severely limits its further application. In this paper, resorcinol/urea-furfural resin was successfully prepared by using cleaner and greener furfural as raw material and co-crosslinking with resorcinol and urea under the action of catalyst. It is noteworthy that during the curing process, KOH is uniformly anchored inside the resin, so the system only needs one-step high-temperature pyrolysis to obtain a N-doped ant-nest-like three-dimensional interconnected porous carbon material. Consequently, the porous carbon exhibited an impressive specific capacitance of 283F g−1. The assembled symmetrical device shows a capacitance retention of 92 % after 50 000 cycles, showing excellent cycle stability. In addition, the assembled zinc ion hybrid capacitor exhibits a capacitance of 138 mAh g−1 and an energy density of 111 Wh kg−1. The one-step carbonization-doping-activation strategy of this bottom-up in-situ anchoring activator will provide further insights into the hierarchical pore structure design of porous carbon and facilitate the simple and efficient preparation of carbon materials.

Sustainable pyrolytic carbon negative electrodes for sodium-ion batteries

Considering both sustainability and potential applications in various industrial sectors, pyrolytic carbon from the recycling of organic solid wastes can play a significant part in the unfolding energy revolution. Further innovations in circular-economy waste loops can facilitate higher economic benefits and lower environmental impacts, where a number of opportunities for improving pyrolytic carbon by choices of precursors, easy regulation of pyrolysis conditions and potential post-treatments. Here we propose a method to synthesize sustainable high-quality nanotube-like pyrolytic carbon using waste pyrolysis gas from the decomposition of waste epoxy resin as precursor, and conduct the exploration of its properties for possible use as a negative electrode material in sodium-ion batteries. The obtained pyrolytic carbon shows better cycling and rate performance than benchmark commercial hard carbon, retaining ∼105 mA h g−1 after 2000 cycles at 100 mA g−1 and exhibiting ∼57 mA h g−1 at 1 A g−1. Since the slope-dominated nature of pyrolytic carbon leads to high performance dependence on defects and pore structure, we therefore also investigate the preferred design of pore structure via pore-forming by post-treatment. It is found that reversible adsorption/desorption on defect sites and optimal pore structure are highly needed for pyrolytic carbon toward practical applications. This work highlights the potential of waste pyrolysis gas itself as a valuable feedstock for the production of value-added carbon materials.

Lightweight and thermally insulating ZnO/SiCnw aerogel: A promising high temperature electromagnetic wave absorbing material with oxidation resistance

Enhancing the microwave attenuation performance under high-temperature and oxidative conditions is a forefront issue for electromagnetic absorption materials. SiC nanowire material exhibits great potential due to its superior thermal stability and oxidation resistance. While, the relatively poor dielectric loss limits its further application as a high effective absorber. In this study, the strategy of laminated porous structure design, as well as the composition of ZnO nanocrystals were applied to promote the microwave attenuation capacity. A simple dual hydrolysis reaction method was employed to grow ZnO nanocrystals on SiC nanowires, followed by the preparation of a 3D layered structure of ZnO/SiCnw aerogel material using directional solidification processes. The ZnO/SiCnw aerogel demonstrated effective broadband attenuation (>90 %) across the entire X-band from room temperature to 873 K. Moreover, the material chemistry remained constant at temperatures as high as 1073 K in air. It exhibited ultralightweight properties and possessed a low thermal conductivity of approximately 0.056 W/m·K, with a density of 0.167 g/cm3. The combination of its lightweight, oxidation resistance, thermal insulation, and attractive X-band absorption efficiency positions ZnO/SiCnw aerogel as a promising EM absorption candidate at both room and high temperatures.

Hierarchical porous structure design and water activation in hydrogels containing hyperbranched peach gum polysaccharide for efficient solar water evaporation

Solar-powered interfacial evaporation is a developing and sustainable technique increasingly utilized in desalination and wastewater purification. This technology involves the creation of cellulose nanofiber (CNF)/polylactic acid (PLA) composite aerogels through the Pickering emulsion approach. Self-floating aero-hydrogel (E-VGP) with a hierarchical porous structure was formed on a viscous mixture containing polyvinyl alcohol (PVA), peach gum polysaccharide (PGP), and polypyrrole (PPy) via an in-situ polymerization process. Furthermore, by modifying the hydrolysis time of PGP with a hyperbranched polyhydroxy structure, VGP hybrid hydrogels of varying microscopic molecular sizes were produced. Additionally, solar vapor generators (SVG) with diverse macroscopic structures were fabricated using molds. The V8G4-12hP0.2 hybrid hydrogel, synthesized using PGP hydrolyzed for 12 h, exhibited an evaporation enthalpy of water at 1204 J g−1. This capacity effectively activates water and enables low enthalpy evaporation. Conversely, the macrostructural design allows the cylindrical rod raised sundial-shaped structure of SVG3 to possess an expanded evaporation area, minimize energy loss, and even harness additional energy from its nonradiative side. Consequently, this micro-macrostructural design enables SVG3 to attain an exceptionally high evaporation rate of 3.13 kg m−2 h−1 under 1 Sun exposure. Moreover, SVG3 demonstrates robust water purification abilities, suggesting significant potential for application in both desalination and industrial wastewater treatment.

A Review on Design and Mechanical Properties of Additively Manufactured NiTi Implants for Orthopedic Applications.

NiTi alloy has a wide range of applications as a biomaterial due to its high ductility, low corrosion rate, and favorable biocompatibility. Although Young’s modulus of NiTi is relatively low, it still needs to be reduced; one of the promising ways is by introducing porous structure. Traditional manufacturing processes, such as casting, can hardly produce complex porous structures. Additive manufacturing (AM) is one of the most advanced manufacturing technologies that can solve impurity issues, and selective laser melting (SLM) is one of the well-known methods. This paper reviews the developments of AM-NiTi with a particular focus on SLM-NiTi utilization in biomedical applications. Correspondingly, this paper aims to describe the three key factors, including powder preparation, processing parameters, and gas atmosphere during the overall process of porous NiTi. The porous structure design is of vital importance, so the unit cell and pore parameters are discussed. The mechanical properties of SLM-NiTi, such as hardness, compressive strength, tensile strength, fatigue behavior, and damping properties and their relationship with design parameters are summarized. In the end, it points out the current challenges. Considering the increasing application of NiTi implants, this review paper may open new frontiers for advanced and modern designs.

Separator structural-chemical features dependency on lithium-ion battery performances

Rechargeable lithium-ion batteries (LIBs) increasingly attract emphasis. Porous construction evolutions during LIBs operation inevitably deteriorate separators mechanical and electrochemical performances. In this research, separators with serial porous constructions are prepared accurately to reveal the dependency mechanism of separator porous structure design on LIB performances. Porous structure analyses, mechanical properties, orientation parameters, and thermal stability diagnosis verify uniform drawing deformations of casting films centralize pore size, optimize pore channel linearity, and retain isotropic texture. Heterogeneous pores with coarse fibrils emphasize under asynchronous drawing, causing worse permeability and anisotropic features, which likely suffered from potential safety hazards caused by excessive unidirectional shrinkage. Electrochemical and battery performance measurements uncover that concentrated pores with superior connectivity determine homogeneous Li+ fluxes, uniformly expand electrodes to impose even compressive stress on separators, and thus reserve initial porous structure maximally to ensure cycling stability. Heterogeneous Li+ fluxes derived from uneven pores with inferior connectivity cause excessive local compression stress on separators. Consequently, mechanically deteriorated porous structure highlight, in reverse impedes Li+ transfer and worsens cell performances. This study suggests separator structural-chemical features function in ensuring LIB performances, which lays solid foundations for separator industrial manufacturing with suitable porous structures for LIBs.

Graphene Aerogel Armed 3D Ordered Mesoporous Carbon as Versatile Anode Platforms for Sodium‐Ion Storage Devices

AbstractThe rise of Na‐storage devices has put forward higher requirements for Na‐storage anode materials with large capacity, long service life, and fast rate capability. Mesoporous carbons, either as active materials or as hosts for guest active nanoparticles, are considered as promising electrode materials. However, addressing the issues of their short lifespan resulting from volume variation and the low coulombic efficiency caused by large surface area via a facile porous structure design still remains a challenge. Herein, a versatile phosphorus‐doped mesoporous carbon (PMC) armed is developed by graphene aerogel (GA) (GA@PMC) for hosting Na‐storage active nanoparticles. As a case study, FeSe2 nanoparticles are selectively supported onto this GA@PMC matrix, creating the FeSe2/GA@PMC composite. When employed in typical Na‐storage devices, such as Na‐ion batteries, Na‐ion hybrid capacitors, and Na‐ion based dual‐ion batteries, the FeSe2/GA@PMC electrode consistently demonstrates superior electrochemical performance. In such GA@PMC, the conformal GA can improve the entire conductivity while decreasing the specific surface area that is directly contacting with electrolyte. The interconnected macroporous structure can not only promote the diffusion of Na+ but also buffers the volume change of the guest active nanoparticles. This bespoke carbon platform synergistically endows the electrode material with enhanced rate capability, cyclic stability, and coulombic efficiency, which are being expected in advanced Na‐storage devices.

Research on Design and Performance of High-Performance Porous Structure Based on 3D Printing Technology

Research on Design and Performance of High-Performance Porous Structure Based on 3D Printing Technology

Enhancing Na-storage property of Na3V2(PO4)3 via porous structure Design：From the perspective of carbon source optimization

The inborn low electronic conductivity of NASCION-type Na3V2(PO4)3 (NVP) restricts its widespread commercial applications. Traditionally carboreduction method could add a thin carbon-layer on the surface of the particles and enhance its conductivity to some extent, while the underlying mechanism about the reducing agent categories is blurred. In this paper, the mechanism of various frequently-selected carbon sources in the carbothermal process has been explored in detail, and the Na-storage property of NVP has been optimized focusing on the categories of the carbon sources. Owning to the acid etching effect of citric acid, carbon-coated NVP (NVP@C) particles synthesized via adopting citric acid as carbon source display tiny particle size as well as porous Na-storage structure. The construction of porous Na-storing structure, coupled with evenly carbon-coating, upgrades the dynamics of ion and electron transportation effectively, enhancing its Na-storing performances. The optimal experiments indicates that NVP@C prepared with citric acid with the overdose coefficient of 125 % (CR125%-NVP) exhibits the optimal electrochemical performances. In detail, CR125%-NVP showcased the initial discharging specific capacities of 116.2 and 101.3 mAh g−1 at 0.1C and 10 C, respectively. It also performed perfect cycle stability, with a capacity retention of 88.9 % after 500 cycles at 10 C rate.

Numerical modeling and performance analysis of anode with porous structure for aluminum-air batteries

Aluminium-air batteries have been considered as one of the most promising next-generation energy storage devices. In this work, based on COMSOL Multiphysics, we firstly explored the effect of 3D pore size structure change on the permeation performance of the solution. The results showed that enhancing the permeation stroke of permeable solutions was beneficial to expanding the electrode reaction contact area, but it would reduce the permeation and corrosion resistance effects. For this reason, we further carried out a secondary study of TPMS structure on fluid permeation and its electrochemical performance based on the TPMS structure modelling mechanism. The results showed that the TPMS structure possessed both good solution permeation reaction rate and good corrosion resistance. Additionally, in order to further verify the validity of the simulation data, we carried out the validation of the self-corrosion rate, discharge properties, and electrochemical properties. From the final data, the discharge voltage of the TPMS structure was only 1.43 V, but its corrosion current and polarisation impedance were 2.207 × 10−2 A/cm2 and 2.2 Ω∙cm2, respectively. At the same time, the structure also had good solution permeability. Therefore the porous anode structure design for aluminium-air batteries in three-dimensional state is preferred.

From clinic to lab: Advances in porous titanium-based orthopedic implant research

Solid titanium alloys are extensively employed in orthopedic applications due to their reliable mechanical strength, but the stress shielding phenomenon caused by its high elastic modulus and the disadvantage of lack of bone integration may lead to clinical complications. The design of porous structure is a feasible approach to reduce the elastic modulus and promote bone and vascular ingrowth. This paper reviewed the application and current challenges of solid titanium implants in orthopedics. To address the drawbacks and explore porous titanium implants that can effectively integrate with bone tissue while possessing sufficient mechanical strength, this review discussed the latest preclinical research from the perspectives of structural design, surface modification, and material composition. The porous structure parameters that affect bone ingrowth and mechanical strength in implants, including porosity, pore size, cellular structure, and gradient structure, were presented. Based on the current research progress, various surface modification techniques aimed at enhancing the performance of porous titanium implants were overviewed. Moreover, a range of titanium alloys including nickel-titanium alloy, β-titanium alloy, high-entropy alloy, and composite alloys are investigated for their prospective applications in orthopedics. Overall, this review provided valuable insights into the current state of research and highlighted the potential of porous titanium alloys in improving clinical outcomes in orthopedics.

“Flexible-strong” polylactic acid porous membrane via tailored polymerization degree of lactic acid side-chains grafting for passive daytime radiative cooler

Aerogel possesses the advantages of high specific surface area, low density, and high porosity, which have shown great application in thermal regulation due to its efficient light scattering capability. However, traditional polymer-based aerogels have poor mechanical properties and lack ductility in outdoor applications, the cooling efficiency of the material is easily affected by damage during transportation, installation, and environmental factors. In this work, combining the porous nature of aerogels and the high ductility of membranes, a polylactic acid-based porous membrane cooler was developed by combining a regular honeycomb surface porous structure design and physical/chemical modification to enhance flexibility, using a simple non-solvent induced phase separation method. This porous membrane exhibits both super-flexibility (116 % elongation at break) and porous characteristics. It achieves a sub-ambient temperature decrease of 4–6 °C under direct sunlight. The optimized porous membrane demonstrates high solar reflectance (94 % of peak reflectivity, 90 % of average reflectivity) and strong infrared emissivity (96 % of peak emissivity, 91 % of average emissivity), it also maintains a solar peak reflectivity of 91 % under 100 % tensile strain and 1000 bending cycles, the cooler still maintains a cooling effect of 2–5 °C below ambient temperature. This work paves the way for developing mechanical flexible and strong radiative coolers for thermal regulation.

Efficient Lithium Transport and Reversible Lithium Plating in Silicon Anodes: Synergistic Design of Porous Structure and LiF‐Rich SEI for Fast Charging

AbstractSilicon (Si) anodes hold great promise for enhancing the energy density of lithium‐ion batteries (LIBs). However, issues such as slow intrinsic kinetics and unstable interfaces caused by significant volume changes hinder the practical deployment of Si anodes. Fast charging is desired by Si‐related issues that worsen Li plating and dead Li, making it essential to overcome these for safe, reversible charging. Herein, a novel approach is proposed by combining structural design and solid electrolyte interface (SEI) modulation to enable efficient and safe fast charging of LIBs. 3D porous micro‐particles consisting of Si nanosheets coated with a pitch‐based carbon layer are successfully prepared. This design provides enhanced ion transport pathways while maintaining the material's intrinsic rate performance and tap density. Furthermore, the designed localized high‐concentration electrolyte (LHCE) exhibits a lower Li+ desolvation energy barrier and leads to the formation of a LiF‐rich SEI, mitigating the Li plating “tip effect” during fast charging, maintaining interface stability, and demonstrating high Coulombic efficiency. Overall, this study highlights the synergistic importance of structure design and SEI regulation in enhancing LIB anodes for fast charging, aiding in developing superior, safe energy storage.

Understanding the role of laser processing parameters and position-dependent heterogeneous elastocaloric effect in laser powder bed fused NiTi thin-walled structures

To reduce the driving load and enhance the heat exchange capacity and elastocaloric refrigeration efficiency, increasing interests in porous structure design and laser-based additive manufacturing (LAM) of NiTi materials with a large specific surface area have been emerging. As a type of characteristic unit of porous components, we mainly focused on the LAM process optimization and elastocaloric effect of NiTi-based thin-walled structures (TWSs) in this work. Firstly, we systemically studied the influence of laser processing parameter on the forming quality and phase transformation behavior of NiTi-based TWS samples. Results showed that high relative density (>99.0%) was inclined to be obtained in a range of 67–133 J mm−3 (laser energy density). Besides, the transformation temperatures (TTs) and enthalpy change roughly showed a positive linear relationship with the applied laser energy density. At an optimized parameter (P = 100 W and v = 1000 mm s−1), the sample exhibited a high relative density (99.88%), good dimensional accuracy, and the lowest TTs. Then, this work emphatically unveiled the position-dependence of phase transformation behavior and elastocaloric effect (eCE) in a NiTi-based TWS sample. It was found that both the TTs and enthalpy change monotonously decreased along the building direction, while the transformation strain kept an increase trend. As a result, the middle portion of the sample exhibited the largest adiabatic temperature change which reached 6.5 K at the applied stain of 4%. The variation in TTs and eCE could be attributed to the heterogeneous solidification microstructure induced by the thermal cycle nature of LAM process.

Fatigue performance of beta titanium alloy topological porous structures fabricated by laser powder bed fusion

The performance of porous β-titanium alloys is crucial for their diverse applications, with fatigue characteristics playing a pivotal role in shaping the design of these porous structures. While topological configurations have exhibited exceptional property, a systematic understanding of their fatigue performance is lacking in recent literature. This study reveals that at a porosity level of ∼75%, designed topologically optimized (TO) structures surpass rhombic dodecahedron (RD) structures in compressive yield strength by ∼4 times (149 ± 3 MPa vs. 38 ± 1 MPa). Furthermore, post-heat treatment further enhances the yield strength of TO structures by ∼15%, reaching 172 ± 3 MPa due to grain refinement and β phase stabilization. Moreover, the as-printed TO structure exhibits exceptional compressive fatigue endurance, enduring stress approximately ∼5 times higher than the as-printed RD structure at a cycle count of 106. Microstructure analysis after fatigue testing reveals a reduction in the α" martensitic phase and an increase in stress-induced ω phase in the heat-treated TO structure, contributing to a slight improvement in fatigue strength compared to the as-printed TO structure. The exceptional fatigue performance observed in LPBF-built beta-type titanium alloy within TO structures highlights the complex relationship between porous structure design, microstructure, compressive strength, and fatigue performance.

Effect of 3D-Printed Porous Titanium Alloy Pore Structure on Bone Regeneration: A Review

As a biomedical material, porous titanium alloy has gained widespread recognition and application within the field of orthopedics. Its remarkable biocompatibility, bioactivity, and mechanical properties establish it as a promising material for facilitating bone regeneration. A well-designed porous structure can lower the material’s modulus while retaining ample strength, rendering it more akin to natural bone tissue. The progression of additive manufacturing (AM) technology has significantly propelled the advancement of porous implants, simplifying the production of such structures. AM allows for the customization of porous implants with various shapes and sizes tailored to individual patients. Additionally, it enables the design of microscopic-scale porous structures to closely mimic natural bone, thus opening up avenues for the development of porous titanium alloy bone implants that can better stimulate bone regeneration. This article reviews the research progress on the structural design and preparation methods of porous titanium alloy bone implants, analyzes the porous structure design parameters that affect the performance of the implant, and discusses the application of porous medical titanium alloys. By comparing the effects of the parameters of different porosity, pore shape, and pore size on implant performance, it was concluded that pore diameters in the range of 500~800 μm and porosity in the range of 70%–90% have better bone-regeneration effects. At the same time, when the pore structure is a diamond, rhombohedral, or cube structure, it has better mechanical properties and bone-regeneration effects, providing a reference range for the application of clinical porous implants.

Mechanochemical production of graphene/amorphous carbon/Mn3O4 nanocomposites for asymmetric supercapacitor

The practical application of graphene/manganese oxide nanocomposites in energy storage presents a significant challenge due to their environmentally unfriendly and complex synthesis, as well as weak interface interactions. Herein, a sustainable and scalable ball milling-thermal annealing method is proposed to produce a graphene/amorphous carbon/Mn3O4 (GACMO) nanocomposite. A triblock copolymer is employed as an intercalator to facilitate the formation of few-layer graphene during ball-milling, a precursor for amorphous carbon to encapsulate Mn3O4 upon thermal-annealing, and thus an intermediate layer to enhance the interface interaction between graphene and Mn3O4. Benefiting from its 3D porous structure and exceptional interface design, GACMO exhibits a large specific surface area, excellent electrical conductivity, enhanced structural stability. Consequently, the GACMO electrode presents a high capacitance of 219 F g−1 at 0.5 A g−1 with a 91.4 % retention at 10 A g−1 after 5000 cycles. Furthermore, the GACMO-based asymmetric supercapacitor shows a high capacitance of 138 F g−1 at 0.5 A g−1, superior energy/power density (62.1 W h kg−1 at 0.45 kW kg−1, 0.6 mW h cm−3 at 9.3 mW cm−3), and promising cycling stability (88.3 % retention after 10,000 cycles). This study brings new insights into the fabrication of graphene/metal oxide-based energy materials.