Three-dimensional Interconnected Network Research Articles

Dual carbon source method to fabricate hierarchical porous carbon with three-dimensional interconnected network structure toward advanced energy storage device

Selective fabrication of carbon materials with developed specific surface area and hierarchical porous structure is essential for high-performance carbon-based supercapacitors. Direct carbonization of organic acid salts represents a strategy that can produce porous carbon with high specific surface area, but it is still hindered by low carbon yield, impeding its large-scale application. Herein, a biomass-derived hierarchical porous carbon with large specific surface area is prepared via a facile one-pot calcination method. The optimal SCPC-4 sample presents three-dimensional interconnected network structure and plentiful heteroatom content. Hence, it delivers a large specific capacitance of 321 F g−1 at a current density of 1 A g−1, and negligible capacitance loss after 10,000 cycles at 10 A g−1. In addition, the assembled SCPC-4 based symmetric supercapacitor exhibits an energy density of 21.2 Wh kg−1 at a power density of 900 W kg−1. This cost-effective binary biomass carbon source route provides a great possibility for the mass production of high-yield porous carbon materials.

Three-dimensional Conductive Interconnected Graphene Networks for High-Performance Electromagnetic Interference Shielding

As electronic and information technology advance, it is critical to reduce the electromagnetic pollution caused by electronic devices. Herein, graphene foam (GF) was prepared via chemical vapor deposition and composited with polydimethylsiloxane (PDMS) to prepare GF/PDMS composites with excellent flexibility. It was discovered that the GF/PDMS composites morphologically coupled to each other to create a low-density porous network with excellent electrical conductivity. A comprehensive investigation of the relationship between electromagnetic interference (EMI) shielding performance and 3D graphene foam growth conditions indicated that the thickness of graphene, influencing the continuity and conductivity of 3D foam, has a critical influence in how well GF/PDMS composites perform in terms of EMI. Furthermore, the electromagnetic shielding effectiveness and absolute effectiveness of the GF/PDMS composites in our work can be higher than 52 dB and 2800 dB·cm2/g, respectively, which is better than most carbon-based EMI shielding materials. The comprehensive studies on GF/PDMS composites in this work will benefit the application of electromagnetic shielding materials for next-generation aviation and wearable devices.

Dealloying-Derived Nanoporous Bismuth for Selective CO2 Electroreduction to Formate

Electrochemical CO2 reduction (CO2ER) to formate is an attractive approach for CO2 utilization. Here, we report a nanoporous bismuth (np-Bi) catalyst fabricated by chemically dealloying a rapidly solidified Mg92Bi8 alloy for CO2ER. The np-Bi catalyst exhibits a three-dimensional interconnected ligament-channel network structure, which can efficiently convert CO2 to formate with a selectivity of ≤94% and an activity of 62 mA cm-2 in a wide potential range. Remarkably, the np-Bi catalyst delivers an industry-level current density of ∼500 mA cm-2 for formate production at a low overpotential of 420 mV in the flow cell. The outstanding CO2ER performance can be attributed to the enlarged surface area with abundant accessible active sites and highly curved surfaces with enhanced intrinsic activity. This work highlights the structural synergies for enhancing CO2ER.

Nacre-inspired cellulose nanofiber/MXene flexible composite film with mechanical robustness for humidity sensing

Inspired by nacre-layered nanostructure, 1D 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-oxidized cellulose nanofibers (TOCNFs) were used as the template to assemble 2D MXene nanosheets into a layered TOCNF/MXene nanocomposite film by a vacuum-assisted filtration strategy. The synergistic effect of the MXene “brick” and TOCNFs “mortar” endowed the composite film with excellent flexibility and a tensile strength of 128.13 MPa, which were attributed to interactions between the interconnected three-dimensional network and multiple hydrogen bonds between TOCNFs and MXene. The humidity-sensing mechanism of the sensor involved the swelling/contraction of channels between MXene interlayers induced by adsorbed H2O and the swelling of TOCNFs. The TOCNF/MXene sensor showed a maximum response (−ΔI/I0) of 90 % under 97 % RH, outstanding bending and folding durability (up to 50 cycles), and long-term stability. Lastly, the sensor could dynamically monitor human respiration, skin, and fingertip humidity, suggesting its promising applications in smart wearable electronics.

A collaborative strategy for encapsulating Sb nanoparticles into porous carbon toward high and stable sodium storage

Antimony (Sb) based materials are considered to be promising materials for sodium (Na) storage due to their high theoretical capacity and appropriate operating voltage. However, the huge volume change during sodiation/desodiation leads to capacity decay rapidly and impedes the practical application. Herein, we embed Sb into the pores of biomass-derived porous carbon to prepare the novel hybrids (Sb@BDPC) through a simple liquid-phase reduction method to improve the cycle stability and specific capacity. The Sb@BDPC hybrids are prepared by Qamgur precursor, exhibiting abundant pore structures and three-dimensional interconnection networks. As anode for sodium-ion batteries (SIBs), the Sb@BDPC hybrids maintain a reversible capacity of 302.7 mAh g−1 at 0.1 A g−1 after 100 cycles, while 168.3 mAh g−1 of capacity remained after 500 cycles at 1 A g−1. Such excellent sodium storage performance is primarily attributed to the synergistic effect of porous carbon and Sb nanoparticles. Specifically, the stable structure with abundant pores of carbon not only provides a channel for fast transfer of charge carriers, but alleviates the volumetric expansion and aggregation of Sb during cycling. These results prove the performance advantages of the composites and provide a simple approach for making full use of disordered porous carbon and constructing Sb-based anode materials toward high and stable energy storage.

Spectroscopic properties of gallium-rich germano-gallate glasses doped with Tm3+

A series of thulium-doped gallium-rich germano-gallate glasses are fabricated and thoroughly investigated. Their synthesis under an atmosphere-controlled glove box allows for a low hydroxyl concentration estimated at 14 wt ppm. From X-Ray diffraction spectroscopy and differential scanning calorimetry, the vitreous state of such gallium-rich BGG composition is confirmed. A structural analysis performed via Raman spectroscopy supports a three-dimensional interconnected glass network of gallium and germanium tetrahedra stabilized by Ba2+ ions as a charge compensator. From steady-state and time-resolved spectroscopies, Judd-Ofelt analysis is applied to determine the radiative transition rates, both absorption and emission cross-sections along with the resonant energy transfer microparameters. Through laser excitation at 808 nm, the intense 1.8 μm trivalent thulium emission is observed, while no concentration quenching is detected. Hence, the present work demonstrates gallium rich-BGG glasses doped with Tm3+ are suitable systems for IR photonic applications, notably for the development of high-power IR lasers.

Bioinspired, High-Strength, and Flexible MXene/Aramid Fiber for Electromagnetic Interference Shielding Papers with Joule Heating Performance.

High-strength, flexible, and multifunctional characteristics are highly desirable for electromagnetic interference (EMI) shielding materials in the field of electric devices. In this work, inspired by natural nacre, we fabricated large-scale, layered MXene/amarid nanofiber (ANF) nanocomposite papers by blade-coating process plus sol-gel conversion step. The as-synthesized papers possess excellent mechanical performance, that is, exceptional tensile strength (198.80 ± 5.35 MPa), large strain (15.30 ± 1.01%), and good flexibility (folded into various models without fracture), which are ascribed to synergetic interactions of the interconnected three-dimensional network frame and hydrogen bonds between MXene and ANF. More importantly, the papers with extensive continuous conductive paths formed by MXene nanosheets present a high EMI shielding effectiveness of 13188.2 dB cm2 g-1 in the frequency range of 8.2-12.4 GHz. More interestingly, the papers show excellent Joule heating performance with a fast thermal response (<10 s) and a low driving voltage (≤4 V). As such, the large-scale MXene/ANF papers are considered as promising alternatives in a wide range of applications in electromagnetic shielding and thermal management.

Amphiphobic polytetrafluoroethylene membrane with a ring-on-string-like micro/nano structure for air purification

Polytetrafluoroethylene (PTFE) membranes with three-dimensional interconnected porous networks are usually used as air filters. However, they are easily contaminated by oily aerosols in air filtration, resulting in a decrease in filtration efficiency. Herein, a strategy for the preparation of amphiphobic PTFE membranes with a ring-on-string-like micro/nano structure for air purification was proposed. First, the PTFE fibers were locked by OTS polysiloxane rings to form an OTS layer with ring-on-string-like structure by spraying octadecyltrichlorosilane (OTS) solution on the membrane surface. Subsequently, fluorinated silica (F–SiO2) nanoparticles were sprayed to build the micro/nano structure and the surface with low surface energy. The prepared amphiphobic membrane had high liquid repellency to water (～153°), diiodomethane (～136°) and hexadecane (～124°). Moreover, the membrane amphiphobicity exhibited a high stability, which can be ascribed to the OTS layer. The layer has a special ring-on-string-like structure and can act as an anchor to fix the nanoparticles on the membrane surface because of the strong interaction between OTS and the nanoparticles. The filtration test results showed that the amphiphobic membrane developed possessed high removal efficiency for 0.1, 0.16 and 0.2 μm particles (˃ 99.9670%). As for the anti-oil fouling ability, the amphiphobic membrane maintained a pressure drop below 3 kPa in the smoke filtration within 10 min, meaning that the membrane developed had a high anti-oil fouling ability. The developed amphiphobic PTFE membrane in this work has a promising prospect in air purification in oil environments.

A pioneering melamine foam-based electrode via facile synthesis as prospective direction for vanadium redox flow batteries

Among the large-scale energy storage devices, vanadium redox flow batteries (VRFBs) are one of the most promising candidates. Carbon felt and graphite felt have been widely adopted as electrodes, however, poor electrochemical activities and low specific surface areas have limited their rollout in the market. Herein, a brand new type of three-dimensional N, P co-doped/reduced graphene oxide (rGO) coated carbonized melamine foam electrode has been proposed to address the above critical issues. Three-dimensional interconnected network structure provides smooth channels for the electrolyte, rGO can further improve the conductivity of the electrode, and heteroatom doping provides additional reaction sites for conversion reactions. Material and electrochemical characterizations demonstrate that the novel electrode possesses a high specific surface area and excellent electrochemical properties. Benefiting from the elaborate design of the electrode structure, the corresponding VRFB is able to yield an energy efficiency of 74.14% at the current density of 300 mA cm−2, and long-term cycling stability is also proved more than 200 consecutive charge–discharge cycles at 200 mA cm−2 without significant decay. All these show that the derivative of melamine foam has enormous advantages and wide application prospects as novel excellent electrode material.

Nanoporous nickel with rich adsorbed oxygen for efficient alkaline hydrogen evolution electrocatalysis

Sluggish water dissociation kinetics severely limits the rate of alkaline electrocatalytic hydrogen evolution reaction (HER). Therefore, finding highly active electrocatalysts and clarifying the mechanism of water dissociation are challenging but important. In this study, we report an integrated nanoporous nickel (np-Ni) catalyst with high alkaline HER performance and the origin of the corresponding enhanced catalytic activity. In 1 mol L−1 KOH solution, this np-Ni electrode shows an HER overpotential of 20 mV at 10 mA cm−2, along with fast water dissociation kinetics. The excellent performance is not only attributed to the large surface area provided by the three-dimensional interconnected conductive network but also from the enhanced intrinsic activity induced by the unique surface properties. Further studies reveal that the types of oxygen species that naturally form on the Ni surface play a key role in water dissociation. Remarkably, when the lattice oxygen almost disappears, the Ni surface terminates with adsorbed oxygen (Oads), exhibiting the fastest water dissociation kinetics. Density functional theory calculation suggests that when Oads acts as the surface termination of Ni metal, the orientation and configuration of polar water molecules are strongly affected by Oads. Finally, the H—OH bond of interfacial water molecules is effectively activated in a manner similar to hydrogen bonding. This work not only identifies a high-performance and low-cost electrocatalyst but also provides new insights into the chemical processes underlying water dissociation, thus benefiting the rational design of electrocatalysts.

Nickel/yttrium iron garnet metacomposites with adjustable negative permittivity behavior toward electromagnetic shielding application

Recent advancement of metacomposites with negative permittivity has provided a new research approach for the design and construction of electromagnetic (EM) shielding materials. Here, we fabricated nickel/yttrium iron garnet (Ni/YIG) metacomposites by a convenient liquid impregnation approach and explored their electromagnetic properties at MHz and Ku bands. As the Ni content increased, some isolated Ni particles formed three-dimensional interconnected networks in the composites, leading to the changes of conducting mechanism and reactance characteristic. A negative permittivity behavior was observed in the composites with high Ni contents, which was put down to low-frequency plasma state of free electrons in the completed Ni networks. The dispersion of negative permittivity at frequencies below 10 MHz was affected by the isolated metal particles and could be well described by the Drude-Lorentz model. An impressive shielding effectiveness of 33.1 dB was achieved at Ku band with a reflection-dominated mechanism, which was ascribed to the negative permittivity induced impedance mismatch. The inductive conducting networks were vital building blocks in the metacomposites for realizing negative permittivity and improving EM shielding performance. This work offered guidance for designing EM shielding metacomposites and promoted the next development of this field.

Preparation of the bioglass/chitosan-alginate composite scaffolds with high bioactivity and mechanical properties as bone graft materials

Bioglass/chitosan-alginate (BCA) composite scaffolds with remarkable performance for bone tissue engineering are successfully prepared by freeze-drying method. The influence of the addition amount of sodium alginate (SA) on the microstructure, porosity, pore size, swelling ratio, degradation ratio, mechanical properties and mineralization ability of BCA composite scaffolds is studied and characterized by various techniques of the scanning electron microscopy, X-ray diffraction, infrared absorption spectrometer and so on. The results show that the BCA composite scaffolds have the three-dimensional interconnected network structure with the high porosity of 82%–87% and a suitable average pore size of 140–200 μm. With the increase of SA addition, the porosity and pore size of BCA gradually reduced and the thickness of pore wall increased. The swelling and degradation ratios decreased gradually with the raising SA and increased with the prolongation of soaking time in PBS. The mechanical strength of BCA was also significantly enhanced, and the mineralization ability of bioglass was effectively deployed with the adding SA of BCA. The improved performance of BCA may be attributed to the formed 3D network structure, activated bioavailability and crosslinking ability between chitosan and SA. It indicates that BCA composite scaffolds have potential applications in bone issues engineering.

Novle layered boron nitride nanosheets/cellulose nanofibers/epoxy composite with high thermal conductivity

Studies have shown that the construction of a three-dimensional interconnected filler network is an effective method to improve the thermal conductivity of the through-plane under a lower filler load. However, huge challenges still exist in building a long-range layered filler network and reducing the thermal resistance resulting from contact between fillers and matrix. In this work, boron nitride nanosheets (BNNSs) were proposed to be connected with modified cellulose nanofibers (CNFs) to obtain a long-range layered structure filler skeleton by bidirectional freezing orientation. Then epoxy resin was dipped under vacuum condition to prepare composite with thermal conductivity up to 1.43 W/mK in through-plane when filler content is 4.3 vol%, and the composite had low thermal expansion coefficient of 64.1 ppm/°C and excellent volume resistivity up to 3.7 × 1012 Ω cm at the same time.

Poly(arylene ether nitrile) porous membranes with adjustable pore size for high temperature resistance and high-performance lithium-ion batteries

In this study, flame-retardant poly(arylene ether nitriles) (PEN) porous membranes are prepared by nonsolvent induced phase separation method. Porous PEN membranes with adjustable morphology are obtained by controlling the Hildebrand solubility parameters between non-solvent and PEN. The obtained PEN porous membranes exhibit much higher porosity and electrolyte uptake compare with commercial separators owing to abundant interconnected pore structure in membranes. High thermal stability and flame retardant properties of PEN membrane ensure the high temperature security of lithium batteries. Especially, PEN-IPA membrane with three-dimensional interconnected dendritic network structure shows the best electrolyte affinity and the highest ionic conductivity (1.47 mS/cm). The LFP||Li half cells assembled with the PEN-IPA separator shows outstanding cycle and C rate performance at 85 °C, the discharge capacity retention of the cell was 86% after 100 cycles at 1 C. Our research reveals the role of the cyano groups in the lithium-ion batteries separator and the relationship between morphology and performance of PEN porous membranes for lithium-ion batteries, which provides a facile and effective approach for preparing the promising separators with adjustable pore size, high temperature resistance and high performance for lithium-ion batteries.

Achieving Cycling Durability of Lithium-Sulfur Batteries via Capturing Polysulfides through a Three-Dimensional Interconnected Carbon Network Anchored with Ultrafine FeS Nanoparticles.

Shuttle effect has always been a critical obstacle to the application of lithium-sulfur (Li-S) batteries for leading to unstable cycle performance and a short lifespan. To solve this problem, a particular strategy is put up to relieve shuttle effect by capturing soluble polysulfides through a three-dimensional interconnected carbon network. Due to the uniformly anchored ultrafine FeS nanoparticles on a 3D interconnected carbon network, the material could lock soluble polysulfides on the cathode side and promote electrochemical conversion reactions among sulfur species. By optimizing the active site exposure of FeS and designing a hierarchical porous and multichannel structure to ensure rapid migration of ions and electrons at the same time, the interlayer can effectively suppress the shuttle effect and enhance sulfur utilization. Thus, the Li-S battery presents excellent cycling stability and rate capability, namely, a reversible specific capacity of 560 mAh g-1 at 2.0 C over 500 cycles with a decay rate of 0.012% per cycle and a specific capacity of 597 mAh g-1 at a 5.0 C current rate. This study offers a promising strategy for designing the structure of an interlayer to achieve long-cycle stable Li-S batteries.

High energy density and extremely stable supercapacitors based on carbon aerogels with 100% capacitance retention up to 65,000 cycles

In terms of ideal future energy storage systems, besides the always-pursued energy/power characteristics, long-term stability is crucial for their practical application. Here, we report a facile and sustainable strategy for the scalable fabrication of carbon aerogels with three-dimensional interconnected nanofiber networks and rationally designed hierarchical porous structures, which are based on the carbonization of bacterial cellulose assisted by the soft template of Zn-1,3,5-benzenetricarboxylic acid. As binder-free electrodes, they deliver a fundamentally enhanced specific capacitance of 352 F ⋅ g-1 at 1 A ⋅ g-1 in a wide potential window (1.2 V, 6 M KOH) in comparison with those of bacterial cellulose-derived carbons (178 F ⋅ g-1) and most activated carbons (usually lower than 250 F ⋅ g-1). The as-assembled supercapacitors exhibit an ultrahigh capacitance of 297 F ⋅ g-1 at 1 A ⋅ g-1, remarkable energy density (14.83 Wh ⋅ kg-1 at 0.60 kW ⋅ kg-1), and extremely high stability, with 100% capacitance retention for up to 65,000 cycles at 6 A ⋅ g-1, representing their superior energy storage performance when compared with that of state-of-the-art supercapacitors of commercial activated carbons and biomass-derived analogs.

Facile and controllable synthesis of AuCu aerogels for the enhanced degradation of 4-nitrophenol

Rationally designing bimetallic nanomaterials with high porosity and large specific surface area has an advantageous effect on enhancing catalytic performance. Bimetallic AuCu aerogels were successfully prepared using the in-situ reductions of Au and Cu precursors without any surfactant. Given its three-dimensional interconnected network and exposed crystal face, AuCu aerogels exhibited considerably excellent catalytic capabilities for the reduction of 4-nitrophenol than other reported Au-based catalysts.

Wrinkled three-dimensional porous MXene/Ni composite microspheres for efficient broadband microwave absorption

In this paper, two dimensional Ti 3 C 2 Tx MXene nanosheets and one-dimensional Ni nanochains are successfully assembled into three dimensional porous MXene/Ni composite microspheres by ultrasonic spray. Their unique micro nano structure and well-designed three-dimensional porous interconnection network can significantly improve the stacking of Ti 3 C 2 Tx MXene nanosheets and the agglomeration of magnetic Ni nanochains. By changing the content of Ni nanochains，we can obtain MXene/Ni composite microspheres with different magnetic content. Due to the difference in conductivity between Ti 3 C 2 Tx MXene and Ni, as well as the newly generated hetero interface and abundant surface groups, MXene/Ni composite microspheres show good impedance matching and excellent electromagnetic wave absorption performance. The minimum reflection loss (RL min ) is −52.7 dB@12.8 GHz, and the corresponding matching thickness is only 1.9 mm. The preparation of MXene/Ni composite microspheres provides a simple and effective method for designing other MXene-based composite materials. • 3D porous MXene/Ni composite microspheres are first formed by simple and rapid ultrasonic spray technology. • MXene/Ni have large specific surface area and abundant pores. • The content of Ni nanochains in MXene/Ni is verified. • The RL min of MXene/Ni is −52.7 dB@12.8 GHz with a thickness of 1.9 mm.

Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm

Magnesium is attractive for the application as a temporary bone implant due to its inherent biodegradability, non-toxicity and suitable mechanical properties. The degradation process of magnesium in physiological environments is complex and is thought to be a diffusion-limited transport problem. We use a multi-scale imaging approach using micro computed tomography and transmission X-ray microscopy (TXM) at resolutions below 40 nm. Thus, we are able to evaluate the nanoporosity of the degradation layer and infer its impact on the degradation process of pure magnesium in two physiological solutions. Magnesium samples were degraded in simulated body fluid (SBF) or Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS) for one to four weeks. TXM reveals the three-dimensional interconnected pore network within the degradation layer for both solutions. The pore network morphology and degradation layer composition are similar for all samples. By contrast, the degradation layer thickness in samples degraded in SBF was significantly higher and more inhomogeneous than in DMEM+10%FBS. Distinct features could be observed within the degradation layer of samples degraded in SBF, suggesting the formation of microgalvanic cells, which are not present in samples degraded in DMEM+10%FBS. The results suggest that the nanoporosity of the degradation layer and the resulting ion diffusion processes therein have a limited influence on the overall degradation process. This indicates that the influence of organic components on the dampening of the degradation rate by the suppression of microgalvanic degradation is much greater in the present study.

Construction of three-dimensional interconnected graphene nanosheet network in thermoplastic polyurethane with highly efficient electromagnetic interference shielding

The achievement of favorable electromagnetic interference shielding at low filler loading integrated with good durability, excellent flexibility is still a great challenge for flexible and wearable electric devices. Herein, graphene nanosheets (GNSs) wrapped melamine foam (MF) (GNSs@MF) is successfully fabricated by repeated dip-drying method using MF skeleton as substrate. The resultant scaffold with interconnected GNSs layer is further infiltrated with thermoplastic polyurethane (TPU). Benefiting from such unique three-dimensional (3D) electrically conductive network, a high electrical conductivity of 45.2 S/m and an exceptional electromagnetic interference (EMI) shielding effectiveness (EMI SE) of 35.6 dB in the X-band are achieved at only 2.01 vol% GNSs loading and 2 mm thickness of TPU-GNSs@MF composites. Importantly, the excellent EMI SE is reliable even the prepared composites undergoing vigorous physical, chemical damages and long-term compression cycles due to the protection of TPU layer and inherent elasticity of MF. In view of the prominent comprehensive performance of the TPU-GNSs@MF composites, this work provides a facile and scalable fabrication of highly-efficient EMI shielding composites for the next-generation portable and wearable electronic devices.