Porous Carbon Composites Research Articles

Two Synthesis Methods for Fe(III)@MOF‐5‐derived Porous Carbon Composites for Enhanced Phenol Hydroxylation

AbstractMOF‐5‐derived porous carbon (MDPC) materials, MDPC‐600 and MDPC‐1000, were prepared by pyrolysis at 600 °C in nitrogen atmosphere prior to acid treatment and at 1000 °C in nitrogen atmosphere, respectively. The samples were characterized by X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), X–MaxN energy spectrum, and transmission electron microscopy (TEM). The test results of MDPC‐1000 and MDPC‐600 show that both are microporous amorphous carbon with the 2.7 nm diameter pore size, indicating that the micropore of MOF‐5 is well preserved during pyrolysis. MDPC‐1000 and MDPC‐600 have specific surface areas of 1570.9 m2/g and 1029.5 m2/g, respectively. MDPC‐1000 and MDPC‐600 were loaded with Fe ions to prepare Fe(III)/MDPC composite materials, which were used as catalysts for phenol hydroxylation. The results show that Fe(III)/MDPC‐1000 has higher catalytic effect than Fe(III)/MDPC‐600. During one hour phenol hydroxylation at 80 °C with 3 wt.% Fe concentration and a mass ratio of catalyst to phenol of 0.053, Fe(III)/MDPC‐1000 provides maximum phenol conversion, dihydroxybenzene yield, and dihydroxybenzene selectivity of 61.4%, 54.3%, and 88.4%, respectively.

Immobilization of cobalt ions using hierarchically porous 4A zeolite-based carbon composites: Ion-exchange and solidification

The efficacy of the synthesized 4A zeolite and the 4A zeolite-based carbon composites were examined for the removal of cobalt ions from an aqueous solution by ion-exchange. Two types of agricultural waste were chosen as precursors to prepare the porous supports for composites synthesized at hydrothermal conditions. The maximum exchange capacity of zeolite portions present in 4A zeolite/Almond shells carbon (AAS) and 4A zeolite/Walnut shells carbon (AWS) reached to 235.175 and 202.887 mg ion/g zeolite; but it reached to 99.525 mg ion/g zeolite for 4A zeolite (A) at same conditions. Removal of cobalt ions by ion-exchange process enhanced when the temperature and pH of the cobalt solution increased. The equilibrium data are precisely fitted by the Freundlich model with a correlation factor (R2) of 0.9807, 0.9859 and 0.9857 for A, AAS and AWS. The cobalt uptake by zeolite-based carbon composites process is controlled by ion-exchange. The Weber and Morris intra-particle diffusion kinetics and Boyd model equations confirmed enhancement of cobalt removal using the composites. The seepage of cobalt ions from the solidified ion-exchangers encapsulating ions reduced to 0.01 ppm in H2O and to 0.05-0.25 ppm in 0.5 N NaCl solution.

Polyoxometallates@zeolitic-imidazolate-framework derived bimetallic tungsten-cobalt sulfide/porous carbon nanocomposites as efficient bifunctional electrocatalysts for hydrogen and oxygen evolution

Hydrogen is one of the most promising sustainable energy among numerous new energy resources. Electrocatalytic water splitting for H2 generation is a clean and sustainable approach due to the use of widely existed water as resource. The searching for efficient and low-cost non-precious metal based electrocatalysts for water splitting, including both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), still remains a great challenge. In this work we report a simple method that utilizes the one-pot in-situ synthesized POMs@ZIFs (POMs = Polyoxometallates, ZIFs = Zeolitic imidazolate frameworks) as precursor for the production of WS2/Co1-xS/N, S co-doped porous carbon nanocomposite as efficient electrocatalysts. These precursors POMs@ZIFs can effectively prevent the agglomeration of metal compound particles during heat treatment and lead to homogeneous dispersion of metal active sites within carbon matrix. The resulting bimetallic Co–W sulfide/heteroatom doped porous carbon composites show significant improvement in electrocatalytic activity towards both OER (Tafel slop of 53 mV dec−1 with overpotential of 0.365 V @10 mA cm−2 current density in 1 M KOH solution) and HER (Tafel slop of 64 mV dec−1 with overpotential of −0.250 V @−10 mA cm−2 current density in 0.5 M H2SO4 solution). This work opens up a new way to obtain low cost bifunctional electrocatalysts towards both OER and HER in water splitting.

Hybridization of MOFs and graphene: A new strategy for the synthesis of porous 3D carbon composites for high performing supercapacitors

A novel porous 3D-structured carbon composite material with a unique architecture by combining graphene and carbonized metal-organic framework (C-MOF) (HKUST-1) microrods for high performing supercapacitors has been synthesised and characterised. The HKUST-1 microrods were prepared by a new method, converting their diamond-like shape into microrods via mechanical shear mixing in an aqueous solution. Grinding of HKUST-1 and graphene oxide (GO) resulted in the formation of a 3D GO-MOF composite with intercalated HKUST-1 microrods between GO sheets. The composite film was treated by a laser scribing method and created a highly porous, a high surface area (>600 m2/g) and conductive 3D nanostructured composite film (L-rGO-C-MOF) used as electrodes for supercapacitor applications. The prepared film showed a high capacitance of 390 F/g at 5 mV/s, and a cyclic stability of 97.8% at 10 A/g after 5000 cycles. The symmetrical supercapacitor delivered an excellent power density of 8037.5 W/kg with an outstanding energy density of 22.3 Wh/kg confirming a new pathway to design new 3D porous graphene-MOF composites for high-performance energy storage devices.

Fabrication of CoNPs-embedded porous carbon composites based on morphochemical imprinting strategy for detection of H2O2 released from living cells

Rational construction of biosensor to determine reactive oxygen species (ROS) generated from living cells is one of the great challenges in physiological and pathological fields. Herein, for the first time, a novel Co nanoparticles (CoNPs) embedded walnut-like N-doped porous carbon microsphere (Co@NCS) can be synthesized using dual imprinting strategy by pyrolysis and acid leaching. The distinct morphology and chemical characteristic of melamine cyanurate (MC) aggregates can be imprinted in the carbon source derived from glucose during the pyrolysis process. According to our research, with synergistic effect of CoNPs and NCS, the Co@NCS shows an excellent electrochemical activity toward the reduction of hydrogen peroxide (H2O2). The Co@NCS modified electrode exhibits a wider linear detection response with the range from 0.5 μM to 7500 μM and a low detection limit of 88 nM (S/N = 3). Moreover, with desirable selectivity, decent reproducibility and satisfied anti-interference performance, the fabricated biosensor can be applied to determine H2O2 in human serum samples and that released from living cell, indicating the potential applications in the fields of pathological and physiological sensing.

Platinum Supported Nitrogen-Doped Carbon Nanotubes/ZIF-8 Derived Carbon Composite Electrodes for a Methanol Oxidation.

Pt-supported on ZIF-8 derived porous carbon (CZIF8) and nitrogen-doped multi-walled carbon nanotubes (NCNT) composites was prepared by pyrolysis process and chemical reduction. The electrochemical characterization and morphological analysis of composites was measured by cyclic voltammetry (CV), chronoamperometry, transmission electron microscope (TEM), and fourier transform infrared spectroscopy (FT-IR). These results indicate that the Pt-NCNT@CZIF8 nanocomposite showed electrochemically superior properties to methanol oxidation reaction and the higher electrochemical surface area (ECSA). Also, ZIF-8 derived carbon and modified the CNTs was thought to enhance the effective area of the platinum deposition site.

Achieving Excellent Electromagnetic Wave Absorption Capabilities by Construction of MnO Nanorods on Porous Carbon Composites Derived from Natural Wood via a Simple Route

Absorbers with light weight, low filler loading, high absorption capacity, and broad absorption bandwidth are highly desirable for electromagnetic (EM) wave absorption application, and extensive efforts in designing excellent performance biomass-derived microwave absorbents using sustainable and renewable materials have been made. Here, for the first time we constructed flexible and high-performance EM-absorbing materials of porous biomass-derived carbon (PBDC) decorated with in-situ grown MnO nanorods (MnOnrs) by a simple process. The chemical composition and microstructural feature of these MnOnrs/PBDC composites are highly dependent on the content of MnOnrs controlled through the concentration of potassium permanganate, and thus their EM properties could be also manipulated. Compared with the pure PBDC, the MnOnrs/PBDC composites exhibited excellent EM wave absorption performance with the minimum reflection loss (RLmin) of −51.6 dB at 10.4 GHz with a thickness of 2.47 mm and a qualified bandwidth of 14...

Novel porous carbon composites derived from a graphene-modified high-internal- phase emulsion for highly efficient separation and enrichment of triazine herbicides

In this study, novel porous carbon composites were successfully prepared with graphene-modified high-internal-phase emulsions (HIPEs) via a simple process of polymerization followed by carbonization. The morphology of the macroporous composites was observed and the verification of structural and functional groups were verified by scanning electron microscopy (SEM), and other characterizations techniques including Fourier transform infrared (FI-IR), X-ray photoelectron spectroscopy (XPS) spectra and Raman spectroscopy. The prepared porous carbon composites were applied to farmland water for the simultaneous adsorption of triazine herbicides and the conditions of extraction and desorption were optimized. Due to the π-π interaction and hydrophobic interaction between triazine herbicides and carbon composites, the maximum adsorption capacity of simazine, prometon and prometryn were 33.4, 34.5 and 33.8 μg g−1, respectively. Adsorption and desorption of triazine herbicides can be achieved in 10 min, and high-speed mass transfer was observed. The calibration curves of three triazine herbicides were linear (R2 ≥0.9996) in the range from 25.0 to 500.0 ng mL−1. The LOD of three triazine herbicides by using the proposed SPE-HPLC-DAD method were 2.5–5.6 ng mL−1. All the results suggest that these materials may be useful for more efficient hazardous residue separations.

Green synthesized gold nanoparticle dispersed porous carbon composites for electrochemical energy storage

Gold (Au) nanoparticles (NPs) have been prepared successfully by Green synthesis method using the reducing agent extracted from Solanum nigrum leaf (SNL). Gold nanoparticles dispersed porous carbon (G5/c and G10/C) composites have been prepared by the pyrolysis of the colloidal gold. The presence of antioxidant compounds in SNL extract is responsible for reducing the gold nanoparticles. The synthesized nanocomposite contains small-sized spherical nanoparticles and porous carbon. Electrochemical energy storage performance of the porous carbon/gold nanoparticle composite is evaluated in symmetric two electrode configuration. An aqueous symmetric supercapacitor based on G10/C composite electrode exhibits a gravimetric specific capacitance of 80 F g−1 at 1 A g−1 and retains a cycling stability of 93% even after 5000 charge-discharge cycles.

MnO2-decorated hierarchical porous carbon composites for high-performance asymmetric supercapacitors

In this study, the growth of 1-dimensional manganese oxide (δ-MnO2) nanowire on hierarchical ordered mesoporous carbons/graphene composites (C) was synthesized by a relatively low-cost, simple, effective and eco-friendly redox process. It is found in both experimental results and theoretical simulations that the carbon surface, especially the mesoporous channels of ordered mesoporous carbons (amorphous carbons), would be favorable to serve as the nucleated sites for the growth of MnO2 nanowires. Likewise, the strong adsorptive interactions between MnO2 and amorphous carbons result in the high deposition efficiency of MnO2 on C (98%) and the outstanding stability of MnO2-decorated hierarchical porous carbon composites (MnO2@C) together with the relatively low equivalent series resistance. This electrode material exhibits excellent electrochemical behavior with a specific capacitance high up to 756.2 F g−1 in KOH electrolytes. In addition, an asymmetric supercapacitor (ASCs) assembled by using MnO2@C and C as the positive and negative electrodes in 1.0 M Na2SO4 solution achieves a maximum energy density of 34.56 Wh kg−1 at a power density of 450 Wkg-1 and excellent cycling stability. The results demonstrate the MnO2-decorated hierarchical porous carbon composites are promising candidates for the future high-performance supercapacitors.

MOF-derived rambutan-like nanoporous carbon/nanotubes/Co composites with efficient microwave absorption property

Nanoporous carbon (NPC) composites embedded with magnetic nanoparticles have been widely studied for applications in microwave absorption. Herein, highly porous rambutan-like carbon composites decorated with controllable carbon nanotubes (CNTs) and Co nanoparticles were synthesized through a thermal decomposition of Co-doped zeolitic imidazolate frameworks-8 (ZIF-8) under different temperatures. The MOF-derived carbon nanocomposites with the cobalt content accounting for 30% of the total mass of cobalt and zinc, carbonized at 700 °C, exhibited excellent microwave absorption property of −30.2 dB. Characterizations exhibit that the in-situ generated Co nanoparticles are uniformly embedded into NPC matrix, which are surrounded by highly graphitized CNTs. The research presents a facile and promising route for rapid mass production of metal-doped NPC/CNTs composites for high-efficiency microwave absorption.

Biomass‐Derived N, O, and S‐Tridoped Hierarchically Porous Carbon as a Cathode for Lithium−Sulfur Batteries

AbstractRestraining soluble polysulfides from diffusing out of the cathode is fundamental to the development of high‐performance lithium−sulfur batteries. The porous architecture and unique physicochemical characteristics of biomass‐derived carbon materials makes it possible to improve the battery performance. Here, two types of porous carbon composites (NOSPC‐1 and NOSPC‐2) with in situ N, S and O tri‐doping are obtained from yam via chemical activation. Structural analysis reveals that NOSPC‐1 presents a highly graphitized interconnected micro‐/mesoporous architecture. As a sulfur host, NOSPC‐1‐800 with 70% sulfur initiates a high reversible discharge capacity of 1556 mAh g−1 at 0.2 C. The cathode further exhibits superior rate performance and long cycle life with 401.2 mAh g−1 reversible capacity and more than 95% coulombic efficiency after 450 cycles at 1 C. Our findings provide meaningful insights toward exploring novel biomass‐derived carbon materials for advanced Li−S batteries.

Phase Controlled Synthesis of Pt Doped Co Nanoparticle Composites Using a Metal-Organic Framework for Fischer–Tropsch Catalysis

Recently, metal nanoparticles embedded in porous carbon composite materials have been playing a significant role in a variety of fields as catalyst supports, sensors, absorbents, and in energy storage. Porous carbon composite materials can be prepared using various synthetic methods; recent efforts provide a facile way to prepare the composites from metal-organic frameworks (MOFs) by pyrolysis. However, it is usually difficult to control the phase of metal or metal oxides during the synthetic process. Among many types of MOF, recently, cobalt-based MOFs have attracted attention due to their unique catalytic and magnetic properties. Herein, we report the synthesis of a Pt doped cobalt based MOF, which is subsequently converted into cobalt nanoparticle-embedded porous carbon composites (Pt@Co/C) via pyrolysis. Interestingly, the phase of the cobalt metal nanoparticles (face centered cubic (FCC) or hexagonal closest packing (HCP)) can be controlled by tuning the synthetic conditions, including the temperature, duration time, and dosage of the reducing agent (NaBH4). The Pt doped Co/C was characterized using various techniques including PXRD (powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), gas sorption analysis, TEM (transmission electron microscopy), and SEM (scanning electron microscopy). The composite was applied as a phase transfer catalyst (PTC). The Fischer-Tropsch catalytic activity of the Pt@Co/C (10:1:2.4) composite shows 35% CO conversion under a very low pressure of syngas (1 MPa). This is one of the best reported conversion rates at low pressure. The 35% CO conversion leads to the generation of various hydrocarbons (C1, C2–C4, C5, and waxes). This catalyst may also prove useful for energy and environmental applications.

An Interpenetrating Porous Organic Polymer as a Precursor for FeP/Fe2P‐Embedded Porous Carbon toward a pH‐Universal ORR Catalyst

Interpenetrating porous organic polymers (PNFc-POP) inspired by the structure of DNA were synthesized through a two-stage polymerization method under catalyst-free conditions. A ferrocene-rich hyper-crosslinked polymer (Fc-melamine) was interwoven with cyclotriphosphazene-based conjugated porous polymer (PN-CMP) to obtain an interconnected polymer network (PNFc-POP). The sequential interpenetrating polymer network contained a diverse range of heteroatoms (P, N, O and Fe) and exhibited a large BET surface area. Simple pyrolysis of the dual polymer interweaved skeletons at 900 °C afforded nanocrystalline FeP/Fe2 P-embedded N and P codoped porous carbon composites. The optimal catalyst obtained by the pyrolysis of PNFc-POP at 900 °C (PNFc-900) exhibited hierarchical porosity and large BET surface areas. It also exhibited excellent oxygen reduction reaction catalytic activities over the entire pH range. The onset potential (Eonset =1.01 V) and half-wave potential (E1/2 =0.86 V) of PNFc-900 exceeded those of commercial Pt/C (Eonset =0.99 V and E1/2 =0.84 V) in alkaline conditions. The obtained catalysts with a four-electron transfer pathway for the reduction of oxygen also displayed excellent long-term stability and methanol tolerance.

Ultralight polyethylenimine/porous carbon modified separator as an effective polysulfide-blocking barrier for lithium-sulfur battery

Lithium-sulfur (Li-S) battery has been regarded as one of the most promising next-generation energy storage systems, due to its high energy density and low cost. However, the dissolution of polysulfides to electrolyte and consequent “shuttle effect” still hinder the application of Li-S battery. Here, a polyethylenimine/fish-scale based porous carbon composite (PFPC) with abundant active sites and a relatively compact morphology is prepared by wet impregnation method. Modified separator with the PFPC coating significantly improves the rate capability and cycle stability of Li-S battery. The Li-S battery with the PFPC separator shows a reversible capacity of 638 mAh g−1 after stably cycling for 400 cycles at 1.0 C (1.0 C = 1675 mA g−1) with an ultralow capacity fading rate of 0.030% per cycle. The improved electrochemical performance of Li-S battery can be attributed to the synergistic effect of physical blocking and chemical adsorption of PFPC for polysulfides and the fast electron conduction between adsorbed polysulfides and conductive network. Moreover, the PFPC separator is ultralight with a mass loading of about 0.04 mg cm−2. The good electrochemical performance, facile preparation method and light weight make the PFPC separator promising for the Li-S battery application.

Fabrication of nitrogen-rich three-dimensional porous carbon composites with nanosheets and hollow spheres for efficient supercapacitors

N-Rich 3D porous carbon composites with nanosheets and hollow spheres have been fabricated for efficient supercapacitors.

Interfacial assembled preparation of porous carbon composites for selective CO2 capture at elevated temperatures

Interfacial assembled preparation of nanoclay integrated porous carbon composites shows superior CO2 capture performance at elevated temperatures.

Fabrication and photovoltaic performance of counter electrode of 3D porous carbon composite

Dye-sensitized solar cell (DSSC) has been widely investigated due to its low cost, simple fabrication process, and excellent photoelectric conversion efficiency. Generally, the DSSC is composed of photoanode, electrolyte and counter electrode. At present, platinum (Pt) film delivers the highest photoelectric conversion efficiency in the available counter electrode materials. However, Pt film is very expensive and prepared by relatively complicated and high-cost magnetron sputtering, which seriously hinders the large-scale applications in DSSC. Therefore, it is of highly academic and engineering significance to develop novel counter electrode materials with low cost and high photoelectric conversion efficiency to replace expensive Pt counter electrode. Previous research shows that carbon-based nanomaterials such as graphene and carbon nanotubes ard promising to be used as highly efficient counter electrode materials. However, the high-cost and complicated fabrication process restrict their practical applications in DSSC. To address such issues, here in this work, we present and fabricate a highly efficient and low-cost three-dimensional porous carbon composite, which is constructed by the relatively dense and conductive graphite film as bottom layer (PC layer), and the porous carbon nanoparticle film as top layer (CC layer). Our fabricated DSSC consists of commercial TiO<sub>2</sub> photoanode (m 4 mm×4 mm), and PC, CC, CC/PC composite, or Pt counter electrode with a size of m 8 mm×8 mm. The results show that under illumination (100 mW/cm<sup>2</sup>) provided by a solar simulator, the short circuit current densities (open circuit voltages) of DSSCs with PC, CC, CC/PC, and Pt counter electrodes are 11.45 mA/cm<sup>2</sup> (0.72 V), 11.88 mA/cm<sup>2</sup> (0.73 V), 12.00 mA/cm<sup>2</sup> (0.75 V), and 13.46 mA/cm<sup>2</sup> (0.74 V), respectively. The filling factors of DSSCs with PC, CC, and CC/PC are 56.09%, 59.80%, 65.28%, and 62.69%, respectively; the photoelectric conversion efficiencies of DSSCs with PC, CC, and CC/PC are 4.61%, 5.20%, 5.90%, and 6.26%, respectively. It is noted that compared with CC layer or PC layer counter electrode, the CC/PC counter electrode delivers better photovoltaic performance. Particularly, the filling factor of DSSC with CC/PC (65.28%) is even 4.10% higher than that of DSSC with commercial Pt (62.69%), and the photoelectric conversion efficiency of the CC/PC-based DSSC is as large as 5.90%, which reaches 94.2% of the Pt-based DSSC (6.26%). The excellent performance of DSSC with CC/PC counter electrode is attributed to the unique three-dimensional porous structure, which can not only facilitate the transfer of electrons and ions, but also provide abundant catalytic sites; these synergistic effects greatly enhance the photovoltaic conversion performance of CC/PC-based DSSC.

Frequency Selective Surface Properties of Microwave New Absorbing Porous Carbon Materials Embedded in Epoxy Resin

In this manuscript, the electromagnetic wave absorption properties of sustainable porous carbon composites were evaluated over the X-band frequency range (8.2 - 12.4 GHz). The porous carbon material was made from the byproduct of cellulose production and was used as additive on the development of radar absorbing material (RAM) composites. These porous carbon materials have different characteristics, such as porosity size (180 µm < O1 < 250 µm and 425 µm < O2 < 500 µm) and particle size (ϕ1 < 250 µm and 250 µm < ϕ2 < 425 µm). Composite materials were also studied as frequency selective surface (FSS) structures. It was shown how complex permittivity and reflection loss (RL) can be manipulated over the frequency range using FSS structure. While regular RAM presented RL of 19 dB at ~11.8 GHz, FSS structure presented a RL of 19 dB shifted to 12.4 GHz regarding the same carbon porous material (with particles between 250 and 425 µm and porosity between 180 and 250 µm). It was demonstrated here the potential use of sustainable porous carbon as RAM, and how FSS structure can be used to tune the frequency of the RL maximum peak.

Phosphorene defect/edge sites induced ultrafine CoPx doping during one-pot synthesis of ZIF-67: The boosted effect on electrocatalytic oxygen reduction after carbonization

Design and synthesis of highly effective catalysts for electrochemical oxygen reduction reaction (ORR) with low cost is of great significance due to the purpose of energy conversion and storage. Herein, we report a facile solvothermal method to prepare ultrafine cobalt phosphide (CoPx)-doped Co-based zeolitic imidazole framework (CoPx/ZIF-67). The one-pot synthesis of CoPx/ZIF-67 involves an oxygen-free sealed room-temperature reaction, in which the high chemical activity of rich defect sits in 2D black phosphorus quantum dots (BPQDs) endows edge-selective coordination /reduction of Co ions. Carbonization of CoPx/ZIF-67 at 800 °C can produce CoPx-N-doped porous carbon composites (CoPx-NPC). The as-prepared CoPx-NPC retains the intrinsic morphology of rhombic dodecahedrons, similar to that of NPC derived from ZIF-67. The ultrafine CoPx doping causes chemical and electronic modulation and offers more active electrocatalytic sites etc., so that CoPx-NPC possesses enhanced ORR performance in terms of positive onset-potential (∼−0.06 V vs. SCE), large diffusion limiting current density (−4.703 mA cm−2), high stability, as well as the accelerated reaction kinetics.