3D Porous Materials Research Articles

Benzoic acid-assisted substrate-free synthesis of ultrathin nanosheets assembled two-dimensional porous Co3O4 thin sheets with 3D hierarchical micro-/nano-structures and enhanced performance as battery-type materials for supercapacitors

Two-dimensional (2D) porous materials have been proved to be meritorious for supercapacitors (SCs) due to unique properties of large surface area, superior intrinsic porosity and high electrical conductivity. In this work, we reported for the first synthesis of 2D porous Co3O4 thin sheets assembled by ultrathin nanosheets via direct hydrothermal decomposition of aqueous solution of cobalt nitrate in the presence of benzoic acid (BA) without any template or surfactant. High specific capacity (497, 598.5 and 399 C g−1 at 1.0 A g−1) and remarkable cycling stability (9.8, 6.3 and 13.1% loss over 8000 cycles at 10.0 A g−1) were achieved in a three-electrode system for the Co3O4 thin sheets at 200 °C for 6, 12 and 24 h with different specific surface area of 69.96, 142.15 and 42.07 m2 g−1, which can be attributed to the special structural feature of an open and porous surface layer and the synergistic effect of 2D and 3D structure that significantly facilitates fast electron transport, ion diffusion and intimate electrode/electrolyte contact. Furthermore, an assembled asymmetric supercapacitor (ASC, Co3O4 thin sheets//activated carbon (AC)) can reach a working output potential difference of 0–1.6 V with a maximum energy density of 22.49 Wh·kg−1 at the power density of 800 W kg−1 with excellent cyclic stability (only 8.2% loss of its initial specific capacity value over 10000 cycles). The results show that our synthesis provides a new insight into the fabrication of 2D hierarchical porous Co3O4 thin sheets; in addition, the as-synthesized Co3O4 thin sheets have potential for various applications in SCs, electrochemical sensing, and lithium ion battery.

Superwetting Polymeric Three Dimensional (3D) Porous Materials for Oil/Water Separation: A Review.

Oil spills and the emission of oily wastewater have triggered serious water pollution and environment problems. Effectively separating oil and water is a world-wide challenge and extensive efforts have been made to solve this issue. Interfacial super-wetting separation materials e.g., sponge, foams, and aerogels with high porosity tunable pore structures, are regarded as effective media to selectively remove oil and water. This review article reports the latest progress of polymeric three dimensional porous materials (3D-PMs) with super wettability to separate oil/water mixtures. The theories on developing super-wetting porous surfaces and the effects of wettability on oil/water separation have been discussed. The typical 3D porous structures (e.g., sponge, foam, and aerogel), commonly used polymers, and the most reported techniques involved in developing desired porous networks have been reviewed. The performances of 3D-PMs such as oil/water separation efficiency, elasticity, and mechanical stability are discussed. Additionally, the current challenges in the fabrication and long-term operation of super-wetting 3D-PMs in oil/water separation have also been introduced.

Synthetic strategies of two-dimensional porous materials towards highly effective catalysts

The two-dimensional (2D) porous materials have attracted a lot of attention in the field of catalysis, owing to their porous structures and attractive characteristics. As a kind of highly efficient catalysts, the 2D porous materials possess many distinct advantages, such as the large surface area, abundant catalytic sites, accelerated kinetic mass transfer process, minimized diffusion barrier and the adaptation of volume change. Here, the current progresses of 2D porous catalysts are summarized. The review mainly covers two parts, the first part is the synthetic strategies of 2D porous catalytic materials, secondly, synergistic porous catalysts are introduced, which are explained with the synergistic mechanism between the porous materials. Finally, the current challenges and future directions are concluded. This review provides advantages, synthetic strategies and further exploration of 2D porous materials toward catalysts.

3D Hierarchical Porous Graphene-Based Energy Materials: Synthesis, Functionalization, and Application in Energy Storage and Conversion

The rational development of effective energy materials is crucial to the sustainable growth of society. Here, 3D hierarchical porous graphene (hpG)-based materials with micro-, meso-, and macroporous features have recently attracted extensive research efforts due to unique porosities, controllable synthesis, versatile functionalization, favorable mass/electron transport, and superior performances in which corresponding electrochemical performances are strongly dependent on the nature of the building blocks and structural hierarchy of the assemblies. In this review, recent achievements in the controllable synthesis, versatile functionalization, and device application of 3D hpG-based energy materials will be summarized, including controllable and facile synthesis through chemical vapor deposition on 3D porous templates, post-assembly/treatment of graphene oxide nanosheets, and templated polymerization. In addition, graphene material functionalization through heteroatom doping, spatially confined decoration of active nanoparticles, and surface hybridization of graphene-analogous components to enhance electrochemical properties will be discussed. Furthermore, applications of 3D hpG materials in various electrochemical energy storage and conversion systems will be summarized, including lithium-ion batteries, lithium-sulfur batteries, lithium metal anodes, oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and nitrogen reduction reaction. Overall, this review will comprehensively present the property advantages, design principles and synthesis strategies of 3D hpG-based energy materials and provide guidance in the development of various 2D graphene-analogous materials and nanomaterials for advanced electrochemical energy storage and conversion systems.

Hydrogel self-templated synthesis of Na3V2(PO4)3@C@CNT porous network as ultrastable cathode for sodium-ion batteries

Abstract A hydrogel self-templated method was developed to produce Na3V2(PO4)3@C@CNT 2D porous network (denoted as NVP@C@CNT) comprising 0D carbon coated Na3V2(PO4)3 nanoparticles and 1D carbon nanotubes. Such fascinating architecture offers high electronic and ionic conductivity , structure stability, as well as long-term cycling when used as a cathode for sodium-ion batteries (SIBs). The cathode displays an ultralong cyclability (94% capacity retention after 4500 cycles at 5C) and high rate capability. Such performance derives from the synergistic effect of porous network structure and carbon coating, which accelerates ion diffusion and improves structural integrity. Equally important, the proposed method provides a new avenue for the preparation of 2D porous materials for advanced energy storage applications.

Confined electrochemical catalysis under cover: Enhanced CO2 reduction at the interface between graphdiyne and Cu surface

Two-dimensional (2D) confined catalysis, in which reactions occur in restricted space between metal surface and 2D overlayer, opens up a new thread for enhancement in the performance of common catalysts. In this paper, Cu surface covered with graphdiyne (GDY) is proposed as an excellent catalyst for 2D confined electrochemical CO2 reduction. Density functional theory calculations reveal the superiority of GDY overlayer in reducing the free energies of key intermediates and onset voltage. In the confined space underneath GDY cover, reaction intermediates are stabilized due to charge transfer between adsorbates and GDY. With large holes as molecular tunnels, GDY has an advantage over graphene in 2D confined catalysis. Our findings inspire a new method to enhance the performance of catalysts through coating with porous 2D materials.

3D Heteroatom-Doped Carbon Nanomaterials as Multifunctional Metal-Free Catalysts for Integrated Energy Devices.

Sustainable and cost-effective energy generation has become crucial for fulfilling present energy requirements. For this purpose, the development of cheap, scalable, efficient, and reliable catalysts is essential. Carbon-based heteroatom-doped, 3D, and mesoporous electrodes are very promising as catalysts for electrochemical energy conversion and storage. Various carbon allotropes doped with a variety of heteroatoms can be utilized for cost-effective mass production of electrode materials. 3D porous carbon electrodes provide multiple advantages, such as large surface area, maximized exposure to active sites, 3D conductive pathways for efficient electron transport, and porous channels to facilitate electrolyte diffusion. However, it is challenging to synthesize and functionalize isotropic 3D carbon structures. Here, various synthesis processes of 3D porous carbon materials are summarized to understand how their physical and chemical properties together with heteroatom doping dictate the electrochemical catalytic performance. Prospects of attractive 3D carbon structural materials for energy conversion and efficient integrated energy systems are also discussed.

Title Confined Sn Nanoparticles into 3D Porous Carbon Skeleton for High Performance Lithium Storage

AbstractSn‐based materials, one of the most promising alternatives, hold higher theoretical capacity (994 mA h g−1) than traditional graphite anodes and attract great attention in lithium‐ion batteries (LIBs). In this work, an in‐situ formed sodium chloride (NaCl) is employed as the template to support the formation of a three‐dimensional (3D) hierarchical porous carbon skeleton. The 3D porous materials, which specific surface area reach 221.1 m2/g, can shorten the ions transport path and increase the contact between the electrode and the electrolyte. Meanwhile, the Sn nanoparticles are restricted in the carbon matrix, which can effectively enhance the conductivity and solve some major problems of the volume fluctuation, particle aggregation and electrode pulverization. Consequently, the 3D porous carbon skeleton/Sn (3D‐PCSS) composites exhibit a high capacity (1046.7 mA h g−1 at 50 mA g−1 after 60 cycles), long cycle life (490 mA h g−1 after 600 cycles at 1000 mA g−1) and excellent rate performance. Moreover, a new method to improve energy storage properties in LIBs will be involved‐confining Sn nanoparticles in hierarchically porous 3D carbon skeleton.

Fabrication of highly pressure-sensitive, hydrophobic, and flexible 3D carbon nanofiber networks by electrospinning for human physiological signal monitoring.

Three-dimensional (3D) porous nanostructure materials have promising applications in pressure sensors or other situations. However, the low sensing sensitivity of these materials restricts precise detection of physiological signals, and it is still a challenge to manufacture highly pressure-sensitive materials, which simultaneously possess other versatile properties. Herein, a simple and cost-efficient strategy is proposed to fabricate versatile 3D carbon nanofiber networks (CNFNs) with superior pressure-sensitivity through electrospinning and thermal treatment. The pressure sensitivity of the CNFNs is 1.41 kPa-1, which is much higher than that of similar 3D porous materials. Unlike traditional carbonaceous materials, the CNFNs exhibit excellent flexibility, stable resilience, and super compressibility (>95%), because of the nano-reinforce of Al2O3. Benefiting from the robust mechanical and piezoresistive properties of the CNFNs, a pressure sensor designed with the CNFNs is able to monitor human physiological signals, such as phonation, pulse, respiration and human activities. An arch-array platform for direction identification of tangential forces and an artificial electronic skin bioinspired by human's hairy skin have been ingeniously designed. The CNFNs also present other versatile characteristics as well, including ultralight density, hydrophobicity, low thermal conductivity, and low infrared emissivity. Therefore, the CNFNs have promising potential in a wide range of applications.

Synthesis of Three Dimensional Porous Carbon Materials Using g-C3N4 as Template for Supercapacitors

Great efforts have been dedicated to fabricating electrode materials of supercapacitors especially for carbon-based system. To achieve satisfied device performance, the fabrication of electrodes generally involved complicated procedure, poisonous agents, and expensive materials. Herein, we develop a facile and economical method to prepare carbon-based electrode materials. The nitrogen-rich g-C3N4 is used as template and N source, and glucose is used as C source to prepare N-doped 3D porous carbon materials by hydrothermal treatment followed by calcinations. The structure and N content could be adjusted by hydrothermal temperature. The specific surface area of 954 m2 g−1 and 11% N content is achieved, thus providing the excellent carrier storage ability and electrocatalytic activity. The supercapacitors fabricated from present 3D carbon networks achieve a specific capacitance of 90F/g, and shows excellent cycling stability. Present method is free of involving complicating procedure and poisonous reagents for fabrication of 3D carbon structures.

Three-dimensional porous carbon materials and their composites as electrodes for electrochemical energy storage systems

This review describes the recent progress of 3D porous carbon materials and their composites as electrodes for electrochemical energy storage systems.

Sakura-based activated carbon preparation and its performance in supercapacitor applications.

3D porous carbonaceous materials were prepared by combining pre-carbonization and KOH activation with sakura petals as raw materials. The prepared porous sakura carbon (SAC-4) exhibits a high specific surface area, a suitable pore size distribution, a low proportion of oxygen-rich groups and N functional groups, and a partially graphitized phase, which are very beneficial for the electrochemical performance of the material as a supercapacitor electrode. In the activation step, when the mass ratio of KOH to sakura carbon (SC) is 4, a supercapacitor is prepared. A maximal specific capacitance of 265.8 F g−1 is obtained when the current density is 0.2 A g−1. When the current density is 1 A g−1, after 2000 cycles in succession, the capacitance retention rate is excellent and the cycling stability can reach as high as 90.2%. The obtained results indicate that porous carbon prepared with sakura blossom as the raw material is an effective and environmentally friendly electrode material for energy storage.

Iron/Nitrogen/Phosphorus Co-Doped Three-Dimensional Porous Carbon as a Highly Efficient Electrocatalyst for Oxygen Reduction Reaction

Developing low cost, high active and stable non noble electrocatalysts for oxygen reduction reaction (ORR) is of great importance for the practical application of proton exchange membrane fuel cells (PEMFCs). Herein, we develop a hydrogel-pyrolysis strategy to synthesize an active iron/nitrogen/phosphorous co-doped carbon electrocatalyst (denoted as PANI-Fe/PA-N1050) by adopting aniline, phytic acid and iron trichloride as the precursors. The catalytic behavior for ORR in 0.1M NaOH solution was examined by cyclic voltammetry (CV), linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results show that, compared with the single-doped counterparts, the iron/nitrogen/phosphorous co-doped carbon electrocatalyst exhibits a superior ORR performance in terms of an initial half-wave potential of 0.84 V vs. RHE and degradation of 14 mV after 1000 cycles. The performance enhancement could be attributed to the following aspects: (1) the crosslink of phytic acid and polyaniline forms a hydrogel, which after pyrolysis possesses high electrochemical surface area so that allows to accommodate quantity of active sites; (2) the Fe, N, P triple-doping generates abundant active sites including Fe-Nx, graphitic N and P-doped carbon; (3) the charge transfer resistance decreases benefiting from the continuous 3D porous structure of carbon. The iron/nitrogen/phosphorous co-doped 3D porous carbon materials prepared by the facile and scalable hydrogel-pyrolysis route is also promising for energy conversion/storage.

A bifunctional melamine sponge decorated with silver-reduced graphene oxide nanocomposite for oil-water separation and antibacterial applications

Modifying the commercial melamine sponge (MS) that intrinsically possesses highly porous open-cell structure with graphene oxide (GO) or GO-based nanocomposites (NCs) is a facile, effective, and low-cost route to fabricate three-dimensional (3D) porous materials with multifunctionality. Herein, we fabricated two types of 3D MSs that were separately functionalized by the reduced GO (RGO) sheets and Ag/RGO NC through combined methods of chemical reduction and immersion process. The simple immersion process brought out the transition of superhydrophilic MS to highly hydrophobic RGO-MS and Ag/RGO-MS. Due to the unique surface topography and high porosity, the RGO-MS exhibited remarkable absorption capacity of 41–91 times its own weight for a wide range of oils and organic solvents. Both the RGO-MS and Ag/RGO-MS showed excellent oil-water separation efficiencies. The Ag/RGO-MS not only exhibited outstanding absorption capacity and recyclability, but also possessed ideal antibacterial performance towards bacteria of Staphylococcus sciuri, Shewanella MR-1, Pseudoalteromonas lipolytica, and Vibrio natriegens. The Ag/RGO-MS featured with hydrophobicity and antibacterial activity is a promising candidate for potential applications in oil-spill disposal and water disinfection. This study provides an effective strategy for designing and fabricating the 3D porous materials with novel functionalities.

Design Rules for the Generation of Stable Quartet Phases of Nucleobases over Two-Dimensional Materials

Out of the quest to decipher the nature of self-assembly and the underlying thermodynamics for the formation of nucleobase quartets on two-dimensional (2D) materials, molecular dynamics simulations and free-energy calculations are performed for three nucleobases, namely guanine, xanthine, and hypoxanthine. Graphene, hexagonal boron nitride (h-BN), and black phosphorene (black Pn) are shown to maintain all quartet structures over wide ranges of temperatures, and their thermal stabilities follow the order hypoxanthine > guanine > xanthine. Disruption of the structural integrity for quartets is studied at various temperatures employing a careful hydrogen bond analyses protocol. Decay profile for a quartet on different surfaces decreases in the order h-BN > graphene > black Pn. The thermal stability of a single quartet is governed by the free energy gained through quartet formation (ΔΔGsQ), whereas the decay rates in an assembly are influenced by interquartet interactions during collision and ΔΔGsQ. h2D-C2N, a novel 2D porous material is demonstrated to disrupt all types of quartets because of extensive hydrogen bonding with the polar surface. It is revealed that 2D materials, which stabilize nucleobases through π–π stacking and have small corrugation in the free-energy landscape for in-plane molecular translation, are able to stabilize quartets, whereas the presence of localized electron density and hydrogen bond donor sites along with large free-energy barriers for translocation lead to quartet disruption.

3D superhydrophobic sponge with a novel compression strategy for effective water-in-oil emulsion separation and its separation mechanism

Oil/water mixtures are easily converted into microemulsions with high stability and complex structures under the action of surfactant, causing great difficulties for effective separation. In this paper, we report a 3D porous melamine sponge with superhydrophobic and superoleophilic properties via a facile 1,4-conjugate addition reaction between amine and acrylate groups for coating nano-complex on the sponge surface and subsequently covalent modification with amine-functionalized long-chain alkane for decrease the surface energy. In order to satisfy the requirement of pore sizes in emulsion separation, a novel and controllable approach has been explored to control the pore sizes and 3D porous structure of the resultant sponge by the mechanical compression strategy. Notably, when the emulsified oil/water mixtures were poured into the modified sponge with 90% compression degree of its original volume, the demulsification occurred immediately and then the oil phase passed through the sponge quickly, while water droplets were interrupted in the tortuous pore channels. Combined with the special wettability and the novel pore sizes tuning strategy, the resulting sponges can effectively separate a wide range of surfactant-stabilized water-in-oil emulsions with fast permeation flux of 32,500 ± 2000 L m−2 h−1 bar−1 under the action of gravity and extremely high oil purity (>99.97%). It is expected that the superhydrophobic sponge with the novel compression approach can provide a general strategy for 3D porous materials used for effective separation of emulsified oil/water emulsions.

Mechanochemical robust, magnetic-driven, superhydrophobic 3D porous materials for contaminated oil recovery

HypothesisResearch on the fabrication of superwettable adsorbents based on 3D porous materials has been attracting considerable attention due to the large storage space presented in their inner bodies. However, it is rare to present a facile, eco-friendly and ultralow-cost approach to modify the 3D porous materials with magnetism thereby obtaining a remotely controllable superhydrophobic/superoleophilic material. ExperimentsBased on this, the 3D magnetic superhydrophobic porous materials (MSPM) based on adsorbent cotton and sponge as substrates were fabricated by a simple dip-coating method using non-hazardous chemical reagents as raw materials. Changes in pristine materials’ wettability during the fabrication process were illustrated gradually by SEM micrographs and XPS characterization. FindingsThe prepared 3D MSPM exhibits fast magnetic responsivity while the superwettable property of water contact angle reached to 162°, and demonstrated oil/water separation and demulsification with excellent adsorption capacity, high separation efficiency and good reusability. Moreover, the 3D MSPM maintains the superhydrophobicity even if compressed with 50% strain for 200 cycles, or immersed in a harsh chemical environment for more than 3 days. As a result, all these features make the as-prepared 3D MSPM possess a large range of applications in contaminated oil recovery.

Fabrication of nanocellulose/PEGDA hydrogel by 3D printing

PurposeNanocellulose is characterised by favourable biocompatibility, degradability, nanostructure effect, high modulus and high tensile strength and has been widely applied in various fields. The current research in the field of new nanocellulose materials mainly focuses on the hydrogel, aerogel and the tissue engineering scaffold. All of these are three-dimensional (3D) porous materials, but conventional manufacturing technology fails to realise precise control. Therefore, the method of preparing structural materials using 3D printing and adopting the nanocellulose as the 3D printing material has been proposed. Then, how to realise 3D printing of nanocellulose is the problem that should be solved.Design/methodology/approachBy adding the photosensitive component polyethyleneglycol diacrylate (PEGDA) in the aqueous dispersion system of nanocellulose, the nanocellulose was endowed with photosensitivity. Then, nanocellulose/PEGDA hydrogels were prepared by the additive manufacturing of nanocellulose through light curing.FindingsThe results showed that the nanocellulose/PEGDA hydrogels had a uniform shape and a controllable structure. The nanocellulose supported the scaffold structure in the hydrogels. Prepared with 1.8 per cent nanocellulose through 40 s of light curing, the nanocellulose/PEGDA hydrogels had a maximum compression modulus of 0.91 MPa. The equilibrium swelling ratio of the nanocellulose/PEGDA hydrogel prepared with 1.8 per cent nanocellulose was 13.56, which increased by 44 per cent compared with that of the PEGDA hydrogel without nanocellulose.Originality/valueThe paper proposed a method for rapidly prototyping the nanocellulose with expected properties, which provided a theoretical basis and technological reference for the 3D additive manufacturing of nanocellulose 3D structure materials with a controlled accurate architecture.

Vapor phase dealloying: A versatile approach for fabricating 3D porous materials

Three-dimensional porous materials with bicontinuous open porosity represent a new class of functional materials for various applications. Top-down dealloying has been demonstrated to be one of the most effective ways to fabricate 3D porous materials. Vapor phase dealloying, which makes use of the saturated vapor pressure difference between the constituent components in an alloy for selectively removing a less stable element or phase, is a promising versatile method for fabricating porous materials from active metals to inorganic elements. Here, using nickel-zinc and germanium-zinc alloys as the prototypes of single-phase and two-phase precursors, respectively, we report the fabrication of 3D bicontinuous porous Ni and Ge by vapor phase dealloying on the basis of selective element or selective phase evaporations. We also show the incorporation of vapor phase dealloying with chemical vapor deposition for the one-pot growth of 3D nanoporous graphene and the functional applications of vapor phase dealloyed porous Ge as Li ion battery electrodes. This study shines lights on the versatility of vapor phase dealloying for the fabrication of bicontinuous porous materials for a wide range of functional applications.

Laser-Induced Graphene: From Discovery to Translation.

Laser-induced graphene (LIG) is a 3D porous material prepared by direct laser writing with a CO2 laser on carbon materials in ambient atmosphere. This technique combines 3D graphene preparation and patterning into a single step without the need for wet chemical steps. Since its discovery in 2014, LIG has attracted broad research interest, with several papers being published per month using this approach. These serve to delineate the mechanism of the LIG-forming process and to showcase the translation into many application areas. Herein, the strategies that have been developed to synthesize LIG are summarized, including the control of LIG properties such as porosity, composition, and surface characteristics, and the advancement in methodology to convert diverse carbon precursors into LIG. Taking advantage of the LIG properties, the applications of LIG in broad fields, such as microfluidics, sensors, and electrocatalysts, are highlighted. Finally, future development in biodegradable and biocompatible materials is briefly discussed.