3D Porous Network Research Articles

Facile fabrication of polyaniline films with hierarchical porous networks for enhanced electrochemical activity

This paper describes a facile method for fabricating polyaniline (PANI) films with well-defined three-dimensional (3D) porous networks and improved electrochemical activity. The PANI hydrogel pastes with different compositions are directly cast into thin films by the doctor blade technique. After a dehydration step, the conductivity of the PANI drastically increases, while the porous structure with hierarchical macro- and meso-porosity is formed in the PANI film. The electrical conductivity tends to increase with the thickness of the porous PANI film until it fails to form a mechanically stable film not exhibiting cracking problems. We found that the amount of the initiator, the aniline monomer, and the crosslinker significantly affect not only the micro-morphology of PANI films, but also their electrical and electrochemical characteristics. Importantly, when the amounts of the crosslinker and the initiator increase, the polymer film forms with a dense internal morphology with smaller pores. Based on the engineered synthesis composition, we demonstrate a supercapacitor with porous PANI electrodes. Due to the hierarchical porous structure, large surface area and the improved conductivity, the resulting devices show excellent volumetric capacitances, which are comparable to or much higher than those previously reported.

Robust flexible poly(amidoxime) porous network membranes for highly efficient uranium extraction from seawater

The oceans contain 4.5 billion tons of uranium which can supply almost infinite nuclear energy. However, it is an urgent need to develop adsorbents simultaneously possessing enhanced efficiency, collect ability, durability and economy to massively extract uranium from seawater. Herein, a simple two-step process is designed to massively produce pure poly(amidoxime) porous network membranes (PAO PNMs) which exhibit high uranium uptake capacity and excellent mechanical strength. The resulting membranes display high hydrophilicity, flexibility, strength (16.98 MPa tensile strength), stiffness (0.55 GPa Young's modulus), and porosity (3D porous network structure) which arise from a modified phase separation technique, providing the membranes a very high adsorption efficiency of 707 ± 5.8 mg-U/g-Ads in 8 ppm uranium spiked seawater and 9.35 ± 0.47 mg-U/g-Ads in natural seawater, respectively. Furthermore, the membranes exhibit a long service life of over 10 cycles of adsorption-desorption, and they can be massively produced via this facile phase separation technique by being simply immersed in water. Overall, coupled with the techno-economic advantages, these PAO PNMs are promising in industrial uranium extraction from seawater due to their robustness, high-efficiency and low-consumption.

Fabrication of 3D silica with outstanding organic molecule separation and self-cleaning performance

The existing oil-water separation materials are often limited by their cost, efficiency and environmental implications, so they are difficult to achieve effective utilization in industry. Although silica nanoparticles have excellent environmental-friendly and rich raw materials, their use has been restricted due to poor porous structure or complex preparation process. Herein, we adopt a growth-aggregation-modification-growth strategy to prepare superhydrophobic silica with three-dimensional (3D) structure. Findings show that the as-prepared silica has a 3D network structure of a size of 11 µm, a pore volume of 2.79 cm3/g and an absorption capacity of 2.98 mL/g towards castor oil. Particularly, superhydrophobic silica exhibits an outstanding organic molecule separation performance from series of surfactant stabilized oil-in-water emulsions with size less than 10 µm and dyes in water. In addition, the 3D silica can act as a functional additive in polydimethylsiloxane (PDMS) for enhancing its hydrophobicity. The substrates coated with PDMS/silica composite present outstanding oil/water separation and self-cleaning performance which is due to the silica particles have excellent superhydrophobicity and porous 3D network. In terms of the well available low-cost raw materials and simple preparation method, the superhydrophobic 3D silica could find promising applications in the treatment of oily wastewater or preparation of self-cleaning surfaces.

Effect of Salt Concentration on Poly (Acrylic Acid) Hydrogel Electrolytes and their Applications in Supercapacitor

With rapidly rising demand of power in the field of flexible and wearable electronics, electrolytes being one of the influential components of the electrochemical energy storage devices and are getting more attention as their physical and chemical properties play vital role in device performance. Hydrogel electrolytes are emerging as novel materials for use in supercapacitors due to their diverse 3D porous network, bendable structure and tuneable properties. In the present work, Poly (acrylic acid) hydrogel has been synthesized using free-radical polymerization in the presence of chemical crosslinker N,N′-methylene bisacrylamide (MBA). The prepared hydrogels were soaked in four different molar concentration of lithium perchlorate (LiClO4) for 48 h to form double network hydrogel electrolytes. The structural and morphological characteristics of hydrogel electrolytes have been investigated using Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray diffraction and field emission scanning electron microscope (FESEM). In addition, the mechanical strength of hydrogel electrolytes was observed. The electrochemical studies including cyclic voltammetry (CV) and galvanic charge-discharge (GCD) investigated the performance of fabricated cells (AC/AA1/AC, AC/AA2/AC, AC/AA3/AC, and AC/AA4/AC) using hydrogel electrolytes in terms of specific capacitance, energy density and power density. Electrochemical studies show that AC/AA3/AC (activated carbon/acrylic acid (1.5 M LiClO4)/activated carbon) is the optimised electrochemical cell among the fabricated cells of hydrogel electrolytes. AC/AA3/AC achieved maximum specific capacitance of 115 F g−1 at 3 mV s−1 and 132.20 F g−1 at 50 mA g−1 with energy density and power density of 18.36 Wh kg−1 and 1000 W kg−1, respectively. All the results indicated significantly that poly (acrylic acid)/LiClO4 hydrogel electrolytes are competitive candidates for application in supercapacitors.

A flexible biomimetic superhydrophobic and superoleophilic 3D macroporous polymer-based robust network for the efficient separation of oil-contaminated water.

The development of stable 3D surfaces for oil/water separation has been of great interest to researchers. Inspired by the lotus leaf, in this study, a superhydrophobic stable and robust surface was generated by the combination of n-octadecyltrichlorosilane, silica, polypyrrole and polyurethane (ODTCS–SiO2–PP–PU). The constructed 3D network displayed superhydrophobic and superoleophilic behavior with a high water contact angle of 154.7° ± 0.8°. The superhydrophobic behavior of the porous material was found to be stable for months. Apart from the hydrophobicity analysis of the material, the various forms of the materials were investigated via scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). Under the force of gravity, hexane displayed an exceptionally high flux of 102 068 Lm−2 h−1 through ODTCS–SiO2–PP–PU. The macroporous network of ODTCS–SiO2–PP–PU displayed fewer chances of fouling, which is a common issue with membranes. Moreover, its porous network displayed good absorption capacity for various non-polar organic solvents. The maximum absorption capacity observed for toluene was 34 times its own weight. The separation efficiency of various non-polar organic solvents from water was observed in the range of 99.5 to 99.8%. ODTCS–SiO2–PP–PU, due to its superhydrophobicity, 3D porous network, extraordinarily high flux, good absorption capacity, and excellent separation capability, has been established as a good candidate for the separation of organic and oil contaminants from water.

Nucleation density and pore size tunable growth of ZnO nanowalls by a facile solution approach: growth mechanism and NO2 gas sensing properties.

Nanowalls are novel nanostructures whose 3D porous network morphology holds great potential for applications as gas sensors. The realization of such a nanowall-based gas sensor depends directly on the comprehensive understanding of the growth mechanism of the nanowalls. We induced nucleation density and pore size evolution by increasing the dipping and growth times. The investigation indicates that the 3D porous ZnO nanowalls consist of a seed layer of ZnO nanoparticles and a growth layer of the vertically grown ZnO nanosheets. The seed layer nucleation density dominance is driven by the dipping time. The pore size and the height of the as-grown ZnO nanowalls are determined by varying the growth time. Possible growth mechanisms governing the physical characteristics of the synthesized ZnO nanostructures in the solution process are proposed and discussed. The gas sensor that was fabricated from the ZnO nanowall structure exhibited strong dependence on the microstructure, which was mainly determined by the preparation conditions.

A new pillared Cd-organic framework as adsorbent of organic dyes and as precursor of CdO nanoparticles

A new neutral cadmium-organic framework with a pillared layer structure, [Cd3(BTC)2(4-bpdb)2] (H3BTC = benzene-1,3,5-tricarboxylic acid; 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene), has been synthesized via solvothermal reaction of cadmium nitrate with the tricarboxylic acid H3BTC and the linear bispyridyl linker 4-bpdb. The complex has been characterized by single crystal X-ray diffraction, showing to possess a 3D porous network of jcr7 topology. The capability of the prepared MOF in adsorbing the organic dyes Congo Red (CR) and Neutral Red (NR), together with kinetics and thermodynamics of their adsorption, have been investigated in detail. The adsorption process was well described by pseudo-first order and pseudo-second order kinetics for CR and NR, respectively. In addition, conversion of the MOF 3D architecture into nano-sized cadmium oxide particles has also been studied.

Fabrication of petal-like Ni3S2 nanosheets on 3D carbon nanotube foams as high-performance anode materials for Li-ion batteries

We have successfully fabricated petal-like Ni3S2 nanosheets on three-dimensional carbon nanotube foams (Ni3S2@3D-CNTF) via a simple one-pot solvothermal method. The 3D-CNTFs were firstly prepared by reducing greenhouse gas of CO2 with an eco-friendly self-assembly technology. The electrochemical performances of obtained Ni3S2@3D-CNTF composite were evaluated as anode materials for Li-ion batteries, which demonstrates a high reversible capacity of 968.2 mAh g−1 at 0.2 A g−1, good rate performance of 524.1 mAh g−1 at 8 A g−1, and long life cycling stability of 93.6% capacity retention after 900 cycles at 4 A g−1. The excellent rate properties and cycling stability can be ascribed to the 3D porous network structure of carbon and abundant active sites of nanosized Ni3S2 sheets. All these superior electrochemical characteristics indicate that the composite of Ni3S2@3D-CNTF can be considered as a competitive participant for high-performing negative electrode materials for Li-ion batteries.

Patterning Porous Networks through Self-Assembly of Programmed Biomacromolecules.

Two-dimensional (2D) porous networks are of great interest for the fabrication of complex organized functional materials for potential applications in nanotechnologies and nanoelectronics. This review aims at providing an overview of bottom-up approaches towards the engineering of 2D porous networks by using biomacromolecules, with a particular focus on nucleic acids and proteins. The first part illustrates how the advancements in DNA nanotechnology allowed for the attainment of complex ordered porous two-dimensional DNA nanostructures, thanks to a biomimetic approach based on DNA molecules self-assembly through specific hydrogen-bond base pairing. The second part focuses the attention on how polypeptides and proteins structural properties could be used to engineer organized networks templating the formation of multifunctional materials. The structural organization of all examples is discussed as revealed by scanning probe microscopy or transmission electron microscopy imaging techniques.

Laser-induced graphene as the microporous layer in proton exchange membrane fuel cells

Porous nanocarbons have been established as materials of choice in the manufacturing of microporous layers (MPLs) for proton-exchange membrane fuel cells (PEM FCs). However, obtaining mechanically and chemically stable materials at competitive yield-to-cost ratios still remains a critical objective, with pyrolytic techniques having shown great promise for bulk material production. A recent advancement in the field, the acclaimed laser-induced graphene (LIG) method employs low-cost industrial engravers for the laser pyrolysis of polymeric substrates into graphene-based foams with distinctive 3D porous networks. In this work, we apply the LIG method on polyimide precursors to obtain surface-patterned hydrophobic graphene foams, and we develop a low-temperature decal method (LTD-LIG) for the direct transfer of non-sacrificial platinum-coated LIG on Nafion® membranes to serve as the MPL in PEM FCs. Obtained by a readily scalable and inexpensive manufacturing method, the assembled LIG-based FC prototype overcomes the water management and mechanical stability problems typically encountered by graphene-based MPLs to present impeccable fuel crossover and power performance at 888.33 mW cm−2 mg−1 of anodic Pt load at 80 °C and 80% RH, delivering a 20% increase in power density compared to a reference FC bearing a commercial carbon black MPL assembled with the same loadings.

Ultrafine SnO2 nanoparticles encapsulated in 3D porous carbon as a high-performance anode material for potassium-ion batteries

A novel nanocomposite of ultrafine SnO2 nanoparticles encapsulated in 3D porous carbon is prepared by freeze-drying followed with sintering and dealloying strategy. The SnO2 nanoparticles are obtained by selective etching of Cu from Cu6Sn5 nanoparticles. The ultrafine oxide nanoparticles together with 3D porous carbon network are highly effective in accommodating the huge volume change of SnO2 during potassiation and depotassiation processes. As a result, the obtained sample presents excellent potassium-ion storage performance including high reversible capacity (270.3 mAh g−1 at 100 mA g−1 after 200 cycles and capacity retention close to 80%), ultralong cycle lifespan and excellent rate performance (144.6 mAh g−1 at 2 A g−1).

Coagulation mechanism of cellulose/metal nanohybrids through a simple one-step process and their interaction with Cr (VI)

In this work, the coagulation mechanism of the cellulose/metal nanohybrids and the binding mode with Cr (VI) are deeply described. Nanohybrids with 3D porous networks were prepared from cellulose/Fe2O3-SO3H solutions through a simple one-step coagulation process in NaCl aqueous solutions. The structure and properties of nanohybrids were characterized by SEM, EDS, XRD, FTIR, and XPS. The cellulose/metal nanohybrids have a langmuir maximum adsorption capacity of 11.46 mg/g. The dissolved metal nanoparticles could form strong hydrogen bonding with cellulose by breaking the intermolecular hydrogen bonds between the polymer molecules. The porous networks of cellulose/metal nanohybrids provided multiple adsorption sites for Cr2O72− anion through FeO…Cr interactions. The cooperation between cellulose and Fe2O3-SO3H nanoparticles makes the hybrids exhibiting a satisfactory selectivity and affinity for Cr (VI). The cellulose/metal nanohybrids selectively interacted with Cr2O72− via Fe atom from Fe2O3 and oxygen atom from SO3− groups. The Cr (VI) adsorption occurred via a two-step process, the first of them was the initial adsorption of Cr2O72− on cellulose/metal nanohybrids surface, followed by the rearrangement of Cr2O72− molecules and the consecutive growth of Cr2O72− aggregate layers.

Versatile 3D porous recycled carbon garments with fully-loaded active materials in the current collector for advanced lithium-ion batteries

We have developed a new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure and applied it to the current collector for advanced lithium-ion batteries (LIBs). The 3D porous CSF are manufactured from recycled oxidized polyacrylonitrile (Oxi-PAN) staple fibers via the spinning, the knitting, stabilization, and carbonization process in order. Furthermore, we have demonstrated the conductive T-shirts and gloves and investigated the structural, electrical, mechanical, and thermal properties of the CSF through various analytical methods including Joule heating simulation as well as the deformation simulation. The CSF with its 3D porous structure is applied as a current collector for advanced lithium batteries in order to replace the conventionally used metal-based current collector. During battery performances, the porous 3D network structure of the CSF provides effective diffusion pathway for lithium ions during the charge/discharge processes. Consequently, the CSF shows not only the improved cycling stability than that of the conventional aluminum current collector but also demonstrating high-rate performances at high percentage loading of active materials in the current collector. The pouch-type LIBs with the CSF/LiFePO4 composites electrode exhibits excellent mechanical stability and flexibility with showing a discharge capacity of 148.7 mA h g−1 at 2 C over 250 cycles over the 1200 times bending with a radius of 12 mm.

Thermal-Driven Formation of 2D Nanoporous Networks on Metal Surfaces

Controlling the quantum confinement of (spin-dependent) electronic states by material design opens a unique avenue to accelerate the implementation of quantum technology in next generation photonic and spintronic applications. In the nanoworld, two-dimensional porous molecular networks have emerged as highly tunable material platform for the realization of exotic quantum phases for which the nanopores can be tuned by chemical functionalization of the size and shape of the molecules. Here, we demonstrate a new approach to control the periodicity, size, and barrier width in 2D porous molecular networks on surface by tuning the balance between intermolecular and molecule–surface interactions using temperature. At 106 K, the prototypical TPT molecules form nanoporous networks with different periodicity and barrier width depending on the surface reactivity. The network structures continuously transform into a close-packed molecular structure at room temperature. This reversible structural phase transition can ...

NiO/Ni nanocomposites embedded in 3D porous carbon with high performance for lithium-ion storage

The high energy storage devices such as lithium-ion batteries (LIBs) have recently attracted extensive attention, and massive efforts have been made to synthesize the high-performance electrodes for Li-ion storage. Here, a facile in situ synthesis method was proposed to prepare the NiO/Ni nanocomposites embedded in three-dimensional (3D) porous carbon network (denoted as NiO/Ni⊕C). The phase component and microstructure of the NiO/Ni⊕C were detected by using X-ray diffraction, scanning electron microscope and transmission electron microscopy. The NiO/Ni nanocomposites with the particle size of approximately 20–50 nm were uniformly dispersed in the 3D porous carbon matrix. The 3D carbon network is in favor of electrical conductivity, and effectively alleviates the volume effect during lithiation–delithiation processes, and thus help the electrode achieve high electrochemistry performance. The NiO/Ni⊕C electrodes possess a reversible specific capacity of 934 mAh g−1 at a current density of 300 mA g−1, and exhibit a superior rate performance with a specific capacity of 505 mAh g−1 at a current density of 2 A g−1. The NiO/Ni⊕C electrodes maintained a specific capacity of up to 683 mAh g−1 even after 1000 cycles at a current density of 1 A g−1.

Excellent reusability of FeBC amorphous ribbons induced by progressive formation of through-pore structure during acid orange 7 degradation

The high-efficient degrading ability of FeBC amorphous ribbons toward acid orange 7 (AO7) via redox reactions is reported and compared with that of FePC amorphous ribbons. The time required for degrading 50% of AO7 using FeBC amorphous ribbons is only 1/3 of that using FePC amorphous ribbons. In the FeBC amorphous matrix, galvanic cell structures are formed between the Fe-B and Fe-C bonds because of the large difference in their bonding strengths, which contributes to the low reaction activation energy and the high degrading efficiency of FeBC amorphous ribbons. The extremely long service life of FeBC amorphous ribbons comes from the progressive formation of 3D porous nanosheet networks that allow more efficient mass transport and a larger specific surface area. The FeBC amorphous ribbons show a satisfying degrading ability in not only acidic but also neutral and weak alkaline AO7 solutions. This work provides an effective and environmental- friendly material for degrading azo dyes.

Amorphous Sb2S3 Nanospheres In-Situ Grown on Carbon Nanotubes: Anodes for NIBs and KIBs.

Antimony sulfide (Sb2S3) with a high theoretical capacity is considered as a promising candidate for Na-ion batteries (NIBs) and K-ion batteries (KIBs). However, its poor electrochemical activity and structural stability are the main issues to be solved. Herein, amorphous Sb2S3 nanospheres/carbon nanotube (Sb2S3/CNT) nanocomposites are successfully synthesized via one step self-assembly method. In-situ growth of amorphous Sb2S3 nanospheres on the CNTs is confirmed by X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The amorphous Sb2S3/CNT nanocomposites as an anode for NIBs exhibit excellent electrochemical performance, delivering a high charge capacity of 870 mA h g−1 at 100 mA g−1, with an initial coulomb efficiency of 77.8%. Even at 3000 mA g−1, a charge capacity of 474 mA h g−1 can be achieved. As an anode for KIBs, the amorphous Sb2S3/CNT nanocomposites also demonstrate a high charge capacity of 451 mA h g−1 at 25 mA g−1. The remarkable performance of the amorphous Sb2S3/CNT nanocomposites is attributed to the synergic effects of the amorphous Sb2S3 nanospheres and 3D porous conductive network constructed by the CNTs.

3D porous network heterostructure NiCe@NiFe electrocatalyst for efficient oxygen evolution reaction at large current densities

Three-dimensional (3D) self-supporting porous network NiCeOx@NiFeOx electrocatalyst on Ni foam (denotes as NiCe@NiFe/NF-N) is prepared by a simple two step electrodepositing process. NiCe@NiFe/NF-N attains 100 mA/cm2 at overpotential of 254 mV with Tafel slope of 59.9 mV/dec, which is much lower than that of NiCe@NiFe/NF-P, NiFe@NF, NiCe@NF and also commercial RuO2 electrocatalysts. Furthermore, the obtained NiCe@NiFe/NF-N electrocatalyst only needs overpotential of 359 mV to deliver high current densities of 1 A/cm2 and demonstrates excellent stability at such large current densities for 20 h, which is also superior to that of NiCe@NiFe/NF-P electrocatalyst. Further study reveals that the enhanced water oxidation performance of NiCe@NiFe/NF-N electrocatalyst with good stability at high current densities could be attributed to the optimal surface and electronic structures, fast reaction kinetics and high intrinsic catalytic activity. Collectively, such electrocatalyst paves new opportunities for development of low-cost water oxidation electrocatalysts with high current densities for practical water splitting applications.

Three-dimensional porous SnO2@NC framework for excellent energy conversion and storage

SnO2-based materials are deemed to be attractive electrodes for lithium/sodium ion batteries (LIBs and SIBs) and electrocatalytic CO2 reduction reaction (CRR) because of high energy density and large abundance. However, the practical application of the SnO2-based materials is prevented by low electrical conductivity and large volume change. Herein, we construct a three-dimensional (3D) porous network with SnO2 nanoparticles into N-doped carbon (namely P–SnO2@NC) synthesized by freeze drying followed by a pyrolyzation process. In the composite, the 3D hierarchical framework can facilitate the ion penetration and gas diffusion. In addition, the NC network can optimize the conductivity of the material and suppress the electrode material to fall off from the electrode. Therefore, the electrode delivers excellent electrochemical properties with high capacities of 510 mA h g−1 after 1000 cycles for LIBs and 497 mA h g−1 after 500 cycles for SIBs. Furthermore, the electrode shows high selectivity for CRR with a large coulombic efficiency (CE) of 52.7% for HCOOH at 0.6 V.

A Highly Sensitive and Recyclable Ln-MOF Luminescent Sensor for the Efficient Detection of Fe3+ and CrVI Anions.

Two new three-dimensional (3D) LnIII metal-organic frameworks (MOFs) were designed and successfully obtained via a solvothermal reaction between lanthanide(III) nitrates and a semi-flexible carbazole tetracarboxylate acid linker as a high-performance chromophore. 1 and 2 possess porous 3D networks with channels along the a axis, and more importantly, they show a highly sensitive and selective fluorescence quenching response to Fe3+ and CrVI anions. The sensing mechanism investigation revealed that the weak interactions of Fe3+ with nitrogen atoms of carbazole and deprotonated carboxylic acids protruding into the pores of MOFs quenched the luminescence of 1 and 2 effectively. In addition, the competition absorption also played an important role in the luminescence quenching detection of Fe3+ based on 1, and CrVI anions based on 1 and 2. Therefore, 1 and 2 represent an alternative example of regenerable luminescence based sensors for the quantitative detection of Fe3+ and CrVI anions.