Excellent Surface Area Research Articles

Cotton fabrics-derived flexible nitrogen-doped activated carbon cloth for high-performance supercapacitors in organic electrolyte

Activated carbon cloth, due to its excellent flexibility, good conductivity, and high surface area, is featured as a kind of promising material for energy storage devices. However, the non-optimized pore structures limit its application as electrode material in supercapacitors with organic electrolytes, which can provide both high energy density and power density due to the high applied cell voltage. In this paper, nitrogen-doped activated carbon cloth with hollow tubular fiber units, high surface area, controllable hierarchical porous structure, and beneficial surface functional groups, is synthesized via a simple ammonia treatment of commercial cotton fabrics. The resulting organic-electrolyte supercapacitors based on this hierarchical porous hollow carbon cloth exhibit a high specific capacitance (up to 215.9 F g−1 at 1 A g−1), extremely high rate capability (89% from 1 A g−1 to 200 A g−1), small IR drop (0.23 V at 100 A g−1), outstanding cycling stability (98% capacitance retention over 20 000 cycles), as well as good flexibility. This N-doped activated carbon cloth thus overcomes the drawbacks of presently available carbon cloths and opens up a new horizon toward energy storage devices with high energy density at high power density.

Ultralow Surface Tension Solvents Enable Facile COF Activation with Reduced Pore Collapse.

Covalent organic frameworks (COFs) are organic, crystalline, highly porous materials attractive for applications such as gas storage, gas separations, catalysis, contaminant adsorption, and membrane filtration. Activation of COFs removes adsorbed solvents and impurities, but common methods for COF activation can result in the collapse of porous structure and loss of accessible surface areas. Here, we present a study of the impact of solvent surface tension on the activation process and demonstrate that activation using the ultralow surface tension solvent perfluorohexane (PFH) is simple and effective for a range of COF materials. We synthesized six different imine-based COFs through imine condensation reactions between tris(4-aminophenyl)benzene (TAPB) or 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and multifunctional di- and tri-benzaldehydes with different aromatic substituents. For each COF, we performed a solvent wash followed by vacuum drying using six solvents varying in surface tension from 11.9 to 72.8 mN m-1. Through powder X-ray diffraction (PXRD) measurements combined with nitrogen adsorption and desorption analysis, we found that some COF chemistries readily lost their porosity during activation with higher surface tension solvents while others were more robust. However, all COFs could be effectively activated using PFH to produce materials with excellent crystallinity and high surface areas, comparable to those for samples activated using supercritical CO2. This work demonstrates that the solvent surface tension used during activation has a strong impact on the potential pore collapse, and activation using PFH provides a simple and effective activation method to produce COFs with excellent crystallinities and pore structures.

Highly Selective Reduction of Carbon Dioxide to Methane on Novel Nanofibrous CoMn2O4 Catalysts

Mesoporous metals have excellent surface area. These metals can be used to a variety of catalytic usage, particularly to reduce carbon dioxide in to value-added products. The present paper has utilized nanoparticles of fibrous CoMn2O4 that are proposed through a naive wet chemical reduction method as catalyst to carbon dioxide methanation. It is found that methane formation has highly efficient performance as well as selectivity because of their high porosity, high surface energy and controllable crystallinity as well as high number of atomic steps divisions. The nanocatalyst structure of fibrous CoMn2O4 istotally characterized by taking advantage of different techniques including scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and a N2 adsorption/desorption.

Facile One-Step Electrodeposition Preparation of Cationic Pillar[6]arene-Modified Graphene Films on Glassy Carbon Electrodes for Enhanced Electrochemical Performance.

In the present work, we have developed a facile one-step route for preparing electrochemically reduced graphene oxide-cationic pillar[6]arene (ErGO-CP6) nanocomposite films on glassy carbon electrodes (GCEs) directly from graphene oxide-cationic pillar[6]arene (GO-CP6) colloidal solution by using a pulsed electrodeposition technique. The electrocatalytic activity of ErGO-CP6 was examined by studying the oxidations of five purine bases [adenine (A), guanine (G), xanthine (X), hypoxanthine (HX), and uric acid (UA)]. It enhanced the oxidation currents of A, G, X, HX, and UA when compared to unmodified ErGO films and bare GCE, which is considered to be the synergetic effects of the graphene (excellent electrical properties and large surface area) and CP6 molecules (high inclusion complexation and enrichment capability).

Coral-like {SiW10Mn2}-based Mn-MOFs: Facile fabrication with high electrochemical capacitor performance

Developing advanced electrode material with high specific capacitance and long-time cycling stability is significant in supercapacitors domain. Polyoxometalates (POMs) and metal-organic frameworks (MOFs) possessing excellent multi-electron redox properties and controllable surface area, respectively, should be attractive candidates for efficient electrode materials. In this paper, we report a novel coral-like POMs-based Mn-MOFs, i.e. [Mn2 (BTC)4/3(H2O)6]6[K8(SiW10Mn2Cl4O36)] ({SiW10Mn2}@Mn-MOF), fabricating via a straightforward grinding method and explore its electrochemical capacitor performance. The as-prepared {SiW10Mn2}@Mn-MOF shows outstanding specific capacitance (211.0 ​F ​g−1) and long-time cycling stability (96.0% after 5000 cycles), resulting from the synergistic effect among POMs and Mn-MOF. Furthermore, the fully aqueous symmetric supercapacitor (ASS) assembled using {SiW10Mn2}@Mn-MOF as electrode and nickel foam as current collector also exhibits a satisfactory energy density (1.2 ​Wh kg−1 at 211.7 ​W ​kg −1). The synthesis of coral-like POMs-based Mn-MOFs, will guide the development of new and promising electrode materials for supercapacitor.

Enhanced ultrasensitive detection of ozone gas using reduced graphene oxide-incorporated LaFeO3 nanospheres for environmental remediation process

An efficient and facile benign approach to develop reduced graphene oxide (rGO) incorporated into perovskite LaFeO3 nanostructure with excellent surface area to detect ultrasensitive Ozone (O3) gas for environmental remediation has been demonstrated. The prepared rGO/LaFeO3 nanocomposites have diameter in the range ~ 1 μm constituting nanospheres with average size ~ 50 nm. Phase purity and chemical composition of rGO/LaFeO3 nanocomposites were revealed through XRD and XPS analysis. The ozone gas sensing performance of rGO/LaFeO3 nanocomposites was investigated and found to exhibit excellent sensitivity, high selectivity, good response (20 and 31 s) and recovery time (39 and 31 s) for 80 ppb at 100 °C when compared to pure LaFeO3 nanostructures. These results indicate that the composites of rGO not only enhanced the ozone gas sensing response at low ppb concentration, but also a decrease in the working temperature. From these perspectives, rGO/LaFeO3 nanocomposites based ozone gas sensor can be regarded as a promising candidate for environmental remediation process in near future.

Microtube Array Membrane (MTAM)-Based Encapsulated Cell Therapy for Cancer Treatment.

The treatment of cancer has evolved significantly in recent years with a strong focus on immunotherapy. Encapsulated Cell Therapy (ECT) for immunotherapy-based anti-cancer treatment is a unique niche within this landscape, where molecules such as signaling factors and antibodies produced from cells are encapsulated within a vehicle, with a host amount of benefits in terms of treatment efficacy and reduced side effects. However, traditional ECTs generally lie in two extremes; either a macro scale vehicle is utilized, resulting in a retrievable system but with limited diffusion and surface area, or a micro scale vehicle is utilized, resulting in a system that has excellent diffusion and surface area but is unretrievable in the event of side effects occurring, which greatly compromises the biosafety of patients. In this study we adapted our patented and novel electrospun Polysulfone (PSF) Microtube Array Membranes (MTAMs) as a ‘middle’ approach to the above dilemma, which possess excellent diffusion and surface area while being retrievable. Hybridoma cells were encapsulated within the PSF MTAMs, where they produced CEACAM6 antibodies to be used in the suppression of cancer cell line A549, MDA-MB-468 and PC 3 (control). In vitro and in vivo studies revealed excellent cell viability of hybridoma cells with continuous secretion of CEACAM6 antibodies which suppressed the MDA-MB-468 throughout the entire 21 days of experiment. Such outcome suggested that the PSF MTAMs were not only an excellent three-dimensional (3D) cell culture substrate but potentially also an excellent vehicle for the application in ECT systems. Future research needs to include a long term in vivo >6 months study before it can be used in clinical applications.

Enhanced degradation of dyes by Cu-Co-Ni nanoparticles loaded on amino-modified octahedral metal–organic framework

Abstract Materials of Institut Lavoisier (MILs) are metal–organic frameworks (MOFs) that exhibit excellent porosity and high specific surface areas. In this study, trimetallic Cu-Co-Ni nanoparticles (NPs) were anchored to amino-modified MOF MIL-101(Fe) through a direct solution impregnation method to enhance the visible light photo-Fenton reaction. The structure and properties of the NH2-MIL-101(Fe)@CuCoNi composite catalyst were characterised using X-ray diffraction analysis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller measurements, diffuse reflectance spectroscopy, zeta potential measurements, and inductively coupled plasma spectroscopy. The results showed that the Cu-Co-Ni NPs were evenly distributed on the surface and within the cavities of the composite. Further, compared with pure MIL-101(Fe) and NH2-MIL-101(Fe), NH2-MIL-101(Fe)@CuCoNi exhibited a higher light-utilisation rate and better catalytic performance. The 2-h removal rates of the anionic dye methyl blue (MB) and cationic dye crystal violet (CV) under continuous visible light irradiation in the presence of NH2-MIL-101(Fe)@CuCoNi and a trace amount of H2O2 were 99% and 93%, respectively. An analysis of the degradation kinetics indicated that the photocatalytic process followed a pseudo-first-order kinetics model. After five cycles, the composite continued to exhibit a degradation efficiency of approximately 80%; this confirmed its stability. In addition, the results of trapping experiments and electron paramagnetic resonance spectroscopy indicated that the reactive species involved in the degradation of the MB and CV dyes at different pH levels were not the same. While •OH active free radicals were responsible for the removal of MB, •O2− free radicals were responsible for the degradation of CV.

Metoprolol beta-blocker decontamination from water by the adsorptive action of metal-organic frameworks-nano titanium oxide coated tin dioxide nanoparticles

Due to prevalent use, resistance to hydrolysis and confined human metabolism, metoprolol (METP) b-blockers are excessively detected in water effluents and therefore must be removed. Adsorption of METP onto metal-organic frameworks-nano titanium oxide coated tin dioxide (nTiO2@SnO2@Mn(5AB-HQ)) nanocomposite was monitored to examine the potential decontamination from wastewater contaminated. The nTiO2@SnO2@Mn(5AB-HQ) nanocomposite was synthesized by the reaction of 5-azobenzoate-8-hydroxyquinoline (5AB-HQ) with manganese chloride in presence of mixed metal oxides (nTiO2@SnO2) under microwave heating irradiation for 3 min and effectively implemented for adsorption of METP. Excellent surface area was evident (267.75 m2g−1) and the maximum METP recoveries were 65.42, 82.55 and 95.89% using 50, 100 and 150 mg L−1, respectively. The possible interaction mechanisms are suggested to take place by both physical adsorption in the forms of electrostatic and π-π interaction as well as chemical adsorption as coordination bond formation based on the effect of solution pH and zeta potential of METP. Five kinetics models were monitored to assure adsorption fitting of METP via pseudo-second and pore film diffusion models. Seven isotherm models confirmed adsorption suitability of Langmuir and Redlich-Peterson models. Finally, the assembled nTiO2@SnO2@Mn(5AB-HQ) was confirmed as a substantially functionalized and recyclable nanocomposite to afford powerful nanomaterial for water decontamination of metoprolol b-blocker.

Effect of ZnCl2 on properties of graphene produced from palm empty fruit bunch

The production of palm oil in Indonesia is increasing every year. Along with the increase in production, the waste generated by the palm oil mill is also increasing. Waste from the production of palm oil can be used as raw material for high value-added products such as graphene. Graphene is the two dimensional hexagonal lattice of sp2 carbon atoms. Due to its excellent electrical conductivity and high theoretical surface area, graphene has very promising applications in nanoelectronics components including transistors, lithium ion batteries and supercapacitor. This study aims to characterize the effect of activating agent ZnCl2: biomass ratio on the structure and properties of graphene production from palm oil waste with catalyst FeCl3 via two-stage pyrolysis. Experiment results showed that surface properties of graphene sheets depend on the ZnCl2: biomass ratio. The effective surface area increased with increasing ZnCl2: biomass ratio. Graphene sheets shows favourable features such as nanosheet frameworks (2-4 atomic layers), graphite-like interlayer spacing (0.3380 nm) and also high crystalline degree (IG/ID = 9.35).

Utility of Silver Nanoparticles Embedded Covalent Organic Frameworks as Recyclable Catalysts for the Sustainable Synthesis of Cyclic Carbamates and 2-Oxazolidinones via Atmospheric Cyclizative CO2 Capture

The present work introduces the favorable synthesis of porous functionalized nanomaterials with excellent surface area, porosity, and high CO2 capture ability to facilitate cyclizative reactions by...

Rational Design of Hierarchical, Porous, Co-Supported, N-Doped Carbon Architectures as Electrocatalyst for Oxygen Reduction.

Developing highly active nonprecious-metal catalysts for the oxygen reduction reaction (ORR) is of great significance for reducing the cost of fuel cells. 3D-ordered porous structures could substantially improve the performance of the catalysts because of their excellent mass-diffusion properties and high specific surface areas. Herein, ordered porous ZIF-67 was prepared by forced molding of a polystyrene template, and Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) was obtained after further carbonization. Co-NOPC exhibited excellent performance for the ORR in an alkaline medium with a half-wave potential of 0.86 V vs. reversible hydrogen electrode (RHE), which is higher than that of the state-of-the-art Pt/C (0.85 V vs. RHE). Moreover, the substantially improved catalytic performance of Co-NOPC compared with Co-supported, N-doped carbon revealed the key role of its hierarchical porosity in boosting the ORR. Co-NOPC also exhibited a close-to-ideal four-electron transfer path, long-term durability, and resistance to methanol penetration, which make it promising for large-scale application.

Activation of porous magnetized biochar by artificial humic acid for effective removal of lead ions

In this paper, we have successfully prepared porous magnetic biochar with excellent surface area and recovery rate using corn stalks (CS) and waste iron (WI) as precursors. Notably, in order to prevent the incorporated iron oxides from blocking the carbon pores, then resulting in a decrease in specific surface area and reducing the removal efficiency of the material, the optimum range of iron ions can be determined to be 0.04–0.06 mol/L according to the effect of the amount of iron on the magnetic biochar recovery rate and Pb2+ removal capacity. Furthermore, as-synthesized artificial humic acid (A-HA) obtained from waste biomass by hydrothermal humification (HTH) technology has abundant functional groups, which can complex with heavy metals and metal oxides. Therefore, A-HA is introduced as an activator to produce novel porous magnetic biochar materials (AHA/Fe3O4-γFe2O3@PBC) with abundant functional groups (i.e., phenolic−OH, −COOH, etc.), providing high dispersibility and stability, further leading to excellent removal performance (Langmuir removal capacity up to 99.82 mg/g) and recyclable performance (removal capacity after 5 removal cycles is 79.04 mg/g). Multiple removal mechanisms have been revealed, including reduction, complexation, and precipitation.

Building vertically-structured, high-performance electrodes by interlayer-confined reactions in accordion-like, chemically expanded graphite

Graphene has attracted major interests as electrode materials for energy storage applications. However, the major limitation of using blade- or spin-coated graphene films for fabricating electrode is that the basal plane of the flat-lying graphene is orthogonal to the direction of charge transport, causing sluggish charge transfer kinetics for the coated graphene film. Here we propose a general, scalable strategy to prepare vertically-structured hybrid electrodes using accordion-like, chemically expanded graphite (CEG). The coated CEG rods possess two-dimensional (2D) interlayer galleries that are vertically aligned with respect to the substrate because of their large length-diameter ratio, which facilitates high-efficiency ion transport. Due to its excellent wettability and high electrochemical surface areas, these interlayer galleries allow a high loading of redox-active (RA) materials, including metal (Pt), metal hydroxide (Ni(OH)2, Fe2O3 and MnO2) or metal dichalcogenide (MoS2). As an example, Ni(OH)2-infiltrated CEG shows excellent rate-performance and long-term cycling stability when used as electrochemical electrodes in lithium-ion batteries and supercapacitors.

Carbonization and Preparation of Nitrogen-Doped Porous Carbon Materials from Zn-MOF and Its Applications.

Nitrogen-doped porous carbon (NPC) materials were successfully synthesized via a Zn-containing metal-organic framework (Zn-MOF). The resulting NPC materials are characterized using various physicochemical techniques which indicated that the NPC materials obtained at different carbonization temperatures exhibited different properties. Pristine MOF morphology and pore size are retained after carbonization at particular temperatures (600 °C-NPC600 and 800 °C-NPC800). NPC800 material shows an excellent surface area 1192 m2/g, total pore volume 0.92 cm3/g and displays a higher CO2 uptake 4.71 mmol/g at 273 k and 1 bar. Furthermore, NPC600 material displays good electrochemical sensing towards H2O2. Under optimized conditions, our sensor exhibited a wide linearity range between 100 µM and 10 mM with a detection limit of 27.5 µM.

In vitro Evaluation of Carbon‐Based Nanospheres as Drug Delivery Vesicles in Breast Cancer Cell

The application of nanoparticles in cancer treatment allows precise tumor treatment by enhancing drug delivery to the tumor area. To overcome limitations in the drug delivery system, we report carbon‐based nanospheres (CSs) that have high drug loading capacity as well as anti‐cancer effects. Monodisperse and size‐tunable (170–583 nm) CSs with excellent surface area up to 2619 m2/g provided high drug loading capacity in four different types of drugs (doxorubicin, gemcitabine, docetaxel, and paclitaxel), and demonstrated strong anti‐cancer effects against MDA‐MB‐231 human breast carcinoma cells.

Pd NPs Decorated on POPs as Recyclable Catalysts for the Synthesis of 2‐Oxazolidinones from Propargylic Amines via Atmospheric Cyclizative CO2 Incorporation

AbstractA novel approach has been taken for the synthesis of a microporous polymeric materials of BBA‐1 and BBA‐2 (benzene−benzylamine), which is a POP (porous organic polymer) with its excellent surface area determined by BET study, via Friedel‐Crafts alkylation of benzene and benzylamine (or 4‐methoxybenzylamine) by utilizing a cross‐linker (formaldehyde dimethyl acetal) and a promoter (anhydrous FeCl3). Pd NPs were decorated over BBA‐1 and modified BBA‐2 to generate the desired catalysts (Pd@BBA‐1 and Pd@BBA‐2 respectively). The characterizations of the synthesized nanomaterials have been conducted by FE‐SEM, wide‐angle powder XRDmethods, N2 adsorption/desorption studies and high resolution transmission electron microscopy (TEM). Pd NPs decorated porous polymers are described here to facilitate the carboxylative cyclization of several propargylamine derivatives leading to the corresponding desired products (2‐oxazolidinone) under the application of ambient conditions (0.1 MPa of CO2, DMSO, 40–80 °C, 30–60 mg nanocatalyst). The Pd NPs‐loaded POP is competitive with previously reported catalytic systems. These pure polymeric microporous catalytic systems exhibited outstanding catalytic performances for the generation of oxazolidinones from several propargylic amines in the absence of organic and inorganic bases through atmospheric cyclizative CO2 incorporation. The modified nanocatalyst (Pd@BBA‐2) displayed exceptional recycling efficiency for the generation of oxazolidinones up to five runs without any noticeable decay in the activity of Pd@BBA‐2.

Rapid Synthesis of High Surface Area Imine-Linked 2D Covalent Organic Frameworks by Avoiding Pore Collapse During Isolation.

Imine-linked 2D covalent organic frameworks (COFs) form more rapidly than previously reported under Brønsted acid-catalyzed conditions, showing signs of crystallinity within a few minutes, and maximum crystallinity within hours. These observations contrast with the multiday reaction times typically employed under these conditions. In addition, vacuum activation, which is often used to isolate COF materials significantly erodes the crystallinity and surface area of the several isolated materials, as measured by N2 sorption and X-ray diffraction. This loss of material quality during isolation for many networks has historically obscured otherwise effective polymerization conditions. The influence of the activation procedure is characterized in detail for three COFs, with the commonly used 1,3,5-tris(4-aminophenyl)benzene-terephthaldehyde network (TAPB-PDA COF), the most prone to pore collapse. When the networks are activated carefully, rapid COF formation is general for all five of the imine-linked 2D COFs studied, with all exhibiting excellent crystallinity and surface areas, including the highest surface areas reported to date for three materials. Furthermore, to simplify the workup of COF materials, a simple nitrogen flow method provides high-quality materials without the need for specialized equipment. These insights have important implications for studying and understanding how 2D COFs form.

Ultrasonic assisted functionalization of MWCNT and synergistic electrocatalytic effect of nano-hydroxyapatite incorporated MWCNT-chitosan scaffolds for sensing of nitrofurantoin.

In the present work, we report the fabrication of stable composite of chitosan hydrogels (CHI) on multiwalled carbon nanotubes (MWCNT) using a simple ultrasonic-assisted method. Also, rod-like hydroxyapatite nanoparticles (HA NPs) were synthesised using a hydrothermal route and were incorporated into the highly conductive MWCNT-CHI scaffolds using an ultrasonication method. The functionalization of MWCNT and preparation of HA NPs on MWCNT-CHI nanocomposite were done using the sonication over the frequency of 37 kHz with the ultrasonic power capable of 150 W (Elmasonic Easy 60H bath sonicator). The resulting hybrid HA NPs/MWCNT-CHI nanocomposites have an excellent surface area and high surface to volume ratio, which leads to the sensitive detection of nitrofurantoin than pristine MWCNT and HA NPs. The complete elemental and morphological analyses of the HA NPs/MWCNT-CHI nanocomposites were characterised by XRD, FTIR, RAMAN, FESEM, TEM, EDX, and elemental mapping techniques. Electrochemical analysis of the HA NPs/MWCNT-CHI nanocomposites was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry methods. The modified glassy carbon electrode (GCE) of HA NPs/MWCNT-CHI nanocomposites exhibit the nitrofurantoin detection activity at the linear range of 0.005-982.1 µM with the detection limit of 1.3 nM. The synergistic electrocatalytic activity of HA NPs/MWCNT-CHI nanocomposites modified GCE is correlated to the sensitivity of 0.16 µAµM-1 cm-2 with excellent precision and accuracy towards the sensing of nitrofurantoin.

Direct Synthesis of Microporous Bicarbazole-Based Covalent Triazine Frameworks for High-Performance Energy Storage and Carbon Dioxide Uptake.

In this study a series of bicarbazole-based covalent triazine frameworks (Car-CTFs) were synthesized under ionothermal conditions from [9,9'-bicarbazole]-3,3',6,6'-tetracarbonitrile (Car-4CN) in the presence of molten zinc chloride. Thermogravimetric and Brunauer-Emmett-Teller analyses revealed that these Car-CTFs possessed excellent thermal stabilities and high specific surface areas (ca. 1400 m2 /g). The electrochemical performances of this Car-CTF series, investigated by using cyclic voltammetry, showed a highest capacitance of (545 F/g at 5 mV/s), which also exhibited excellent columbic efficiencies of 96.1 % after 8000 cycles at 100 μA/0.5 cm2 . The other Car-CTF samples displayed similar efficiencies. Furthermore, based on CO2 uptake measurements, one of the series showed the highest CO2 uptake capacities: 3.91 and 7.60 mmol/g at 298 and 273 K, respectively. These results suggest a simple method for the preparation of CTF materials that provide excellent electrochemical and CO2 uptake performance.