3DOM Carbon Research Articles

The effect of interconnections on gas adsorption in materials with spherical mesopores: A Monte Carlo simulation study.

Gas adsorption is a standard method for measuring pore-size distributions of nanoporous materials. This method is often based on assuming the pores as separate entities of a certain simple shape: slit-like, cylindrical, or spherical. Here, we study the effect of interconnections on gas adsorption in materials with spherical pores, such as three-dimensionally ordered mesoporous (3DOm) carbons. We consider interconnected systems with two, four, and six windows of various sizes. We propose a simple method based on the integration of solid-fluid interactions to take into account these windows. We used Monte Carlo simulations to model argon adsorption at the normal boiling point and obtained adsorption isotherms for the range of systems. For a system with two windows, we obtained a remarkably smooth transition from the spherical to cylindrical isotherm. Depending on the size and number of windows, our system resembles both spherical and cylindrical pores. These windows can drastically shift the point of capillary condensation and result in pore-size distributions that are very different from the ones based on a spherical pore model. Our results can be further used for modeling fluids in a system of interconnected pores using Monte Carlo and density functional theory methods.

Preparation and cyclic Voltammetric characterization of three-dimensional macroporous carbon electrodes

Three-Dimensionally Ordered Macroporous (3DOM) carbon surfaces were prepared from a template synthesis involving polymethyl methacrylate. These surfaces were mounted as electrodes and studied using cyclic voltammetry to understand their electrochemical properties for potential use as platforms in electrochemical sensors. The prepared 3DOM carbon electrodes have a large surface area that allows more charge-transfer reactions to take place. Potassium hexacyanoferrate and potassium nitrate served as the electroactive species and supporting electrolyte, respectively to study the 3DOM electrodes. Based on the Randles-Sevcik equation, the current produced by the potassium hexacyanoferrate electroactive species, is controlled by diffusion. The electrodes were subsequently chemically modified with 13 nm gold nanoparticles that produced a significant increase in the faradaic current.

Hierarchical nanoarchitectured hybrid electrodes based on ultrathin MoSe2 nanosheets on 3D ordered macroporous carbon frameworks for high-performance sodium-ion batteries

3DOM MoSe2@C constructed by ultrathin MoSe2 nanosheets strongly binging on 3DOM carbon skeleton exerts high energy and power density for sodium-ion batteries.

Flexible, three-dimensional ordered macroporous ZnO electrode with enhanced electrochemical performance in lithium-ion batteries

Metal oxide has attracted large quantities of interests in the field of lithium-ion battery due to its high specific capacity, abundance and environmental benignity. However, the large volume expansion and intrinsic poor electrical conductivity still severely hinder its performance. Herein, a self-supported electrode comprising of three-dimensional ordered macroporous ZnO/Carbon cloth (3DOM ZnO/CC) is prepared through a modified colloid crystal template method. The highly interconnected pores of 3DOM ZnO can alleviate the volume variation, facilitate the penetration of electrolyte and shorten the diffusion distance of Li ions, meanwhile, the tight connection between 3DOM ZnO and carbon cloth can provide continuous transfer path for the electrons, which would substantially enhance the electronic conductivity. When tested as anode in LIBs, the 3DOM ZnO/CC could deliver a high area capacity of 3.19 mAh cm−2 (corresponding capacity is 773 mAh g−1 for the 3DOM ZnO) at the current density of 0.18 mA cm−2 after 100 cycles. The result suggests that combining 3DOM ZnO with the carbon cloth substrate is a reasonable design to improve the electrochemical performance, and it can also be easily expanded to other metal oxide electrode materials.

Carbon dots decorated three-dimensionally ordered macroporous bismuth-doped titanium dioxide with efficient charge separation for high performance photocatalysis

Fast recombination of photo-generated carriers and limited photo-response have greatly hindered the development of TiO2-based photocatalysts. Herein, we present a ternary three-dimensionally ordered macroporous (3DOM) carbon dots (CDs)/Bi:TiO2 photocatalyst, which affords well-designed charge transmission and allows broad-spectrum absorption, thus delivering enhanced photocatalytic performance. The carbon dots act as effective electron extractors to accelerate the separation of electron-hole pairs, and pore engineering of the 3DOM Bi:TiO2 skeleton greatly promotes the response of light in the whole solar spectrum range. Impressively, the 3DOM CDs/Bi:TiO2 catalyst exhibits a greatly enhanced photocatalytic degradation performance toward phenol (92.7% in 2 h), and RhB (96.4% in 40 min) under full-spectra illumination, compared to the pristine 3DOM TiO2. This work provides a new design strategy for the optimization of carriers transmission pathway in high-quality and low-cost photocatalysts.

Surface chemical modification of macroporous and mesoporous carbon materials: Effect on their textural and catalytic properties

Abstract The covalent grafting of Mn(II) Schiff base complexes onto ordered mesoporous (CMK-3) and three-dimensionally ordered macroporous (3DOM) carbon matrices was achieved and the resulting hybrid materials were characterized and evaluated as catalysts for alkene epoxidation with H2O2. The observed high catalytic performance of these hybrid materials is determined by the catalytic efficiency of the grafted Mn-complexes. On the other hand, N2 adsorption/desorption and SEM analysis indicated that the surface chemical modification of the supports occurred in the meso- and micro-porosity of the materials, leaving unaffected the macroporous structure of the 3DOM matrix. Thus, when the support material becomes a non-porous one, it results in very fast catalytic reaction time. In particular, it appears that the about 300 nm cavities of 3DOM do not affect the course of catalysis highlighting the role of the hybrids’ micro-properties. This behavior is discussed and is correlated to the non-porous nature in conjunction with the hydrophobic surface of these carbon materials.

Improved Specific Capacity of Nb2O5 by Coating on Carbon Materials for Lithium‐Ion Batteries

AbstractMaterials for lithium‐ion batteries (LIBs) with excellent electrochemical performance are of significance to meet the increasing demand for rechargeable batteries. Niobium pentoxide (Nb2O5), as an intercalation material with promising electrochemical properties has caught our attention. In this study, Nb2O5 nanoparticles were successfully synthesized through a classical sol‐gel process. The nanoparticles with a size of less than 5 nm were uniformly coated on carbon materials, i. e., reduced graphene oxide (rGO) and three‐dimensionally ordered macroporous (3DOM) carbon, under the same proportion, to explore which kind of carbon materials is more suitable to improve the electrochemical performance of Nb2O5 as an anode for LIBs. Nb2O5/3DOM carbon composite exhibited a superior electrochemical performance to the other two materials, where a high reversible capacity of 519 mA h g−1 could be maintained at the current density of 5.0C (C=201.7 mA g−1). Furthermore, the specific capacity of Nb2O5/3DOM carbon composite maintained 1163 mA h g−1 at the current density of 0.2C (C=201.7 mA g−1) after 100 cycles.

Mixed matrix membranes incorporated with three-dimensionally ordered mesopore imprinted (3DOm-i) zeolite

Abstract MFI and LTA zeolites were synthesized inside three-dimensionally ordered mesoporous (3DOm) carbon. After the removal of the carbon, a highly crystalline 3DOm-imprinted zeolite with tunable and ordered mesopores was obtained. The nominal mesopore size can be finely controlled from 5 to 15 nm by changing the cage size of the 3DOm carbon. Under different synthesis conditions, the crystal size of the 3DOm-imprinted (3DOm-i) MFI was tuned from approximately 100 nm to several micrometers. The 3DOm-i zeolite was mesoporous and exhibited a spherical shape with a rough external surface. With the synthesis of 3DOm-i zeolites, mixed matrix membranes (MMMs) were prepared by incorporating them into a commercial polyimide matrix (i.e., Matrimid® 5218). Both MFI- and LTA-containing MMMs exhibited good adhesion between the zeolites and polymer because of their imprinted mesopore structure and rough external surface. Also, both MMMs exhibited a substantial increase in permeability to all the gas penetrants used in this work (except for NF3), resulting in an excellent N2/NF3 separation efficiency.

Fabrication of BEA/MFI zeolite nanocomposites by confined space synthesis

Two types of BEA/MFI zeolite nanocomposites with hierarchical meso-/microporisty structures were synthesized via two different procedures based on the confined space synthesis strategy. By using the three-dimensionally ordered mesoporous (3DOm) carbon as the confined space provider, BEA and MFI zeolites were successively grown within the 3DOm carbon under an alternated hydrothermal treatment condition, resulting in the product zeolite nanocomposite with an ordered assembly structure constituted by zeolite nanoparticles of two dissimilar frameworks (BEA and MFI) and a three-dimensional highly ordered mesoporosity replicated from the 3DOm carbon template. Another synthesis strategy was by overgrown of MFI crystals over BEA zeolite with a three-dimensionally ordered mesoporous-inprinted structure (3DOm-i BEA), and the obtained BEA/MFI zeolite nanocomposites revealed a hierarchical meso-/microporisty and various intergrowth morphologies.

Synthesis, characterization, and catalytic application of hierarchical SAPO-34 zeolite with three-dimensionally ordered mesoporous-imprinted structure

Hierarchical SAPO-34 zeolites with three-dimensionally ordered mesoporous-imprinted structure (3DOm-i SAPO-34) were first confined synthesized within three-dimensionally ordered mesoporous carbons by multiple hydrothermal (MHT) treatments. With perfect structure replication, the obtained 3DOm-i SAPO-34 zeolite particles exhibited unique ordered structures consisting of primary spherical elements of sizes determined by mesopore cages of the corresponding carbon templates, and the sizes of mesopores constituted by the adjacent spherical elements can be precisely tuned from 5.5 to 13.0 nm by varying the 3DOm carbon. The as-synthesized hierarchical 3DOm-i SAPO-34 catalysts showed superior catalytic performance in the MTO reaction with prolonged catalytic lifetime and significant improvement of selectivity for light olefins (ethylene and propylene) compared to the conventional microporous SAPO-34.

Ionic Liquids as Electrolytes for Electrochemical Double-Layer Capacitors: Structures that Optimize Specific Energy.

Key parameters that influence the specific energy of electrochemical double-layer capacitors (EDLCs) are the double-layer capacitance and the operating potential of the cell. The operating potential of the cell is generally limited by the electrochemical window of the electrolyte solution, that is, the range of applied voltages within which the electrolyte or solvent is not reduced or oxidized. Ionic liquids are of interest as electrolytes for EDLCs because they offer relatively wide potential windows. Here, we provide a systematic study of the influence of the physical properties of ionic liquid electrolytes on the electrochemical stability and electrochemical performance (double-layer capacitance, specific energy) of EDLCs that employ a mesoporous carbon model electrode with uniform, highly interconnected mesopores (3DOm carbon). Several ionic liquids with structurally diverse anions (tetrafluoroborate, trifluoromethanesulfonate, trifluoromethanesulfonimide) and cations (imidazolium, ammonium, pyridinium, piperidinium, and pyrrolidinium) were investigated. We show that the cation size has a significant effect on the electrolyte viscosity and conductivity, as well as the capacitance of EDLCs. Imidazolium- and pyridinium-based ionic liquids provide the highest cell capacitance, and ammonium-based ionic liquids offer potential windows much larger than imidazolium and pyridinium ionic liquids. Increasing the chain length of the alkyl substituents in 1-alkyl-3-methylimidazolium trifluoromethanesulfonimide does not widen the potential window of the ionic liquid. We identified the ionic liquids that maximize the specific energies of EDLCs through the combined effects of their potential windows and the double-layer capacitance. The highest specific energies are obtained with ionic liquid electrolytes that possess moderate electrochemical stability, small ionic volumes, low viscosity, and hence high conductivity, the best performing ionic liquid tested being 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

In2O3 Nanoparticles on Three-Dimensionally Ordered Macroporous (3DOM) Carbon for Pseudocapacitor Electrodes

We present a facile sol-gel approach for the fabrication of In2O3/3DOM carbon nanocomposites for pseudocapacitor applications. By this facile chemical method, uniform In2O3 nanoparticles can be vertically grown on the surface of 3DOM carbon. The structure and morphology of the material is characterized by X-ray diffraction, nitrogen gas sorption, scanning electron microscope, and transmission electron microscope techniques. Cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) are used to investigate the electrochemical performance of electrodes. An In2O3/3DOM carbon electrode with 10wt.% shows a high specific capacitance of 287Fg−1, while the capacitance of In2O3 electrode alone is 58Fg−1. Furthermore, an In2O3/3DOM carbon nanocomposite pseudocapacitor shows a stable cycle life in the potential range of 0–0.5V and retains 86% of its initial capacitance over 5000 cycles. The high specific capacitance and excellent cycle life are due to the three-dimensionally ordered pore structure of the carbon, which favors the diffusion of the electrolyte ions and provides a conductive scaffold.

Three Dimensionally Ordered Mesoporous Carbon as a Stable, High‐Performance Li–O2 Battery Cathode

AbstractEnabled by the reversible conversion between Li2O2 and O2, Li–O2 batteries promise theoretical gravimetric capacities significantly greater than Li‐ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeOx using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well‐defined pore structures, providing a unique material to gain insight into processes key to the operations of Li–O2 batteries. When decorated with Pd nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000 mAh gcarbon−1 and cyclability of more than 68 cycles.

Three dimensionally ordered mesoporous carbon as a stable, high-performance Li-O₂ battery cathode.

Enabled by the reversible conversion between Li2O2 and O2, Li-O2 batteries promise theoretical gravimetric capacities significantly greater than Li-ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeO(x) using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well-defined pore structures, providing a unique material to gain insight into processes key to the operations of Li-O2 batteries. When decorated with Pd nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000 mAh g(carbon) (-1) and cyclability of more than 68 cycles.

Synthesis of three-dimensionally ordered macroporous manganese dioxide–carbon nanocomposites for supercapacitors

In this article, we report a composite of MnO2 nanoparticles supported by three-dimensionally ordered macroporous carbon (MnO2/3DOM carbon nanocomposites) fabricated by means of a simple multi-component infiltration of three-dimensional templates. MnO2 nanoparticles of 2 nm–6 nm are observed to be highly dispersed on the 3DOM carbon scaffolds. Cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy techniques are employed to assess the properties of these nanocomposites for use in supercapacitors. The results demonstrate that MnO2 can be effectively utilized with assistance of the 3DOM carbon in the electrode. The specific capacitance of the nanocomposite electrode can reach as high as 347 F g−1 at a current density of 0.5 A g−1. Moreover, the electrode exhibit excellent charge/discharge rate and good cycling stability, retaining over 92% of its initial charge after 5500 cycles at a current density of 2.5 A g−1. Such MnO2/3DOM carbon nanocomposite represents a promising exploring direction for enhancing the device performance of metal oxide-based electrochemical supercapacitors.

Synthesis of Hierarchical Sn-MFI as Lewis Acid Catalysts for Isomerization of Cellulosic Sugars

Hierarchical stannosilicate molecular sieves with ordered mesoporosity and MFI topology (three dimensionally ordered mesoporous imprinted (3DOm-i) Sn-MFI) were successfully synthesized within the confined space of three dimensionally ordered mesoporous (3DOm) carbon by a seeded growth method. The obtained 3DOm-i Sn-MFI consisting of 30 nm spherical elements forming an opaline structure contains highly ordered mesopores ranging from 4 to 11 nm. Compared with conventional Sn-MFI, 3DOm-i Sn-MFI exhibits superior catalytic performance for the isomerization of cellulosic sugars. No diffusion limitation was observed for the isomerization of a triose sugar, dihydroxyacetone (DHA), into methyl lactate (ML). The presence of weak Bronsted acid in the 3DOm-i Sn-MFI catalyst facilitates the reaction by catalyzing the formation of an intermediate, pyruvaldehyde (PA). 3DOm-i Sn-MFI offers significant improvements for the isomerizations of C5 and C6 sugars, such as xylose and glucose, by greatly enhancing molecular tran...

Three-Dimensionally Ordered Mesoporous (3DOm) Carbon Materials as Electrodes for Electrochemical Double-Layer Capacitors with Ionic Liquid Electrolytes

Compared to rechargeable batteries, electrochemical double-layer capacitors (EDLCs) are normally considered to be higher power but lower electrical energy density charge storage devices. To increase the energy density, one can enlarge the interfacial area between electrodes and electrolyte through the introduction of nanopores and employ electrolytes that are stable over wider voltage ranges, such as ionic liquids. However, due to the relatively high viscosity of ionic liquids and large ion sizes, these measures can result in diminished power performance. Here, we describe the synthesis of carbon electrodes that overcome these limitations and simultaneously provide high specific energies and high specific powers in EDLCs using the ionic liquid EMI-TFSI as an electrolyte. A colloidal crystal templating method was optimized to synthesize three-dimensionally ordered mesoporous (3DOm) carbons with well-defined geometry, three-dimensionally interconnected pore structure and tunable pore size in the range from ...

Preparation of a Three-Dimensional Ordered Macroporous Carbon Nanotube/Polypyrrole Composite for Supercapacitors and Diffusion Modeling

Three-dimensional ordered macroporous (3DOM) carbon nanotube (CNT)/polypyrrole (PPy) composite electrodes for supercapacitor application were prepared through cyclic voltammetric copolymerization from a solution containing both acid-treated CNTs and pyrrole monomers. A self-assembled SiO2 colloidal crystal was used as the sacrificial template. After electrochemical copolymerization, the template was removed, and a 3DOM CNT/PPy composite electrode was obtained. The specific capacitance of the composite reached 427 F g–1 at the scanning rate of 5 mV s–1, and it is calculated that ion diffusion contributed approximately 30% to the specific capacitance of the composite. A mathematical model of mass transport was proposed to evaluate the ion diffusion capability on the surfaces of 3DOM, nanoporous, and planar films. The calculation results showed that the flux (i.e., ion flux per unit length) of 3DOM film was larger than that of planar film, while the flux of nanoporous film was close to that of planar film. The model indicates that 3DOM film is favorable for ion transportation, while nanoporous film does the opposite. The model partially explains the reason why the specific capacitance of the prepared 3DOM CNT/PPy composite is far above the specific capacitance values of other reported CNT/PPy composites, even the nanoporous CNT/PPy composite.

Confined synthesis of three-dimensionally ordered mesoporous-imprinted zeolites with tunable morphology and Si/Al ratio

Three dimensionally ordered mesoporous-imprinted (3DOm-i) zeolites with well-controlled mesoporosity and Si/Al ratio were synthesized within the confined space of three dimensionally ordered mesoporous (3DOm) carbon by conventional hydrothermal synthesis method. It was found that the incipient wetness technique used to prepare the 3DOm carbon can significantly affect the mesoporous structure of the resulting carbon template. 3DOm carbon with a nearly complete replication from silica colloidal crystals can be used to control the mesoporosity of 3DOm-i zeolites. Confined synthesis of hierarchical zeolites under conventional hydrothermal synthesis conditions offers a large variety of synthesis recipes for controlling the framework, morphology and composition of 3DOm-i zeolites. It shows that a dilute initial synthesis solution favors the formation of single crystalline 3DOm-i silicalite-1, while a higher starting silica concentration results in polycrystalline 3DOm-i silicalite-1. The polycrystalline feature might benefit the disassembly of the resulting 3DOm-i zeolites for the preparation of highly monodisperse zeolite nanocrystals. 3DOm-i ZSM-5 with tunable acid site concentrations was also achieved by varying Si/Al ratios in initial synthesis solutions. The catalytic performance of 3DOm-i ZSM-5 was tested with the self-etherification of benzyl alcohol, a reaction severely limited by the mass transport of reactants and products in the micropores of ZSM-5 catalysts. It was revealed that for this reaction 3DOm-i structure can significantly improve the reaction rate by alleviating diffusion limitation, and the Si/Al ratio of 3DOm-i ZSM-5 also plays an important role in the effective utilization of the zeolite catalysts.

Structure replication and growth development of three-dimensionally ordered mesoporous-imprinted zeolites during confined growth

Abstract